aboutsummaryrefslogblamecommitdiffstats
path: root/lib/stdlib/test/lists_SUITE.erl
blob: 1f60ed50fef8394d36d3791571fea79950dbaebc (plain) (tree)
1
2
3
4
5
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117


                   
                                                        
   










                                                                           







                                                                    
                                           
 
                              

                                                                    
                                                   



                                          
                                             


                                                            

                                                                
                                  

                                                                     
                                 
                                                    

                                         
                                                       

                                           
                                                       

                                   
                                                          


                                                          
                                                        
                                                   














                                                                      


                                 
 
         













                       

            

                                                
                                                            
                          

                                                    



                                                               

                                                        
                          

                                                      
                           

                                                          

                                                                   
                                                        
                          
                                                        

                                                                     
                                                               

                                                            
      
 





                         
                                     
           

                                    
           
 

                                   
           
 
                                   




                         














































































































































































































                                                                                   


























                                                            




































                                                                       










                                                                       























































































































































































                                                                       

















































































































































































































                                                                           






























































































































































































                                                                             
































































































































































































































































































                                                                              



































































































































                                                                             












































































































































































































































                                                                              
                       














                                                                 
                       






















                                                                      
                       
































                                                                      





                       
                              




























































                                                                       
                       













































































































































































































































































































                                                                              


















































































































































                                                                       




























































































                                                                                 



                                                                             
                                                 
                                         






                                               


       






                                   











                                                                    
                        
                                         


                                                                      




























































































































                                                                                    



















































                                                                 

                                                          










































































































                                                                         








                                                                      




































                                                                
%%
%% %CopyrightBegin%
%% 
%% Copyright Ericsson AB 1997-2013. All Rights Reserved.
%% 
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%%     http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%% 
%% %CopyrightEnd%
%%
%%%----------------------------------------------------------------
%%% Purpose: Test suite for the 'lists' module.
%%%-----------------------------------------------------------------

-module(lists_SUITE).
-include_lib("common_test/include/ct.hrl").

% Test server specific exports
-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
	 init_per_group/2,end_per_group/2]).
-export([init_per_testcase/2, end_per_testcase/2]).

% Test cases must be exported.
-export([member/1, reverse/1,
	 keymember/1, keysearch_keyfind/1,
         keystore/1, keytake/1, keyreplace/1,
	 append_1/1, append_2/1,
	 seq_loop/1, seq_2/1, seq_3/1, seq_2_e/1, seq_3_e/1,
	
	 sublist_2/1, sublist_3/1, sublist_2_e/1, sublist_3_e/1,
	 flatten_1/1, flatten_2/1, flatten_1_e/1, flatten_2_e/1,
	 dropwhile/1, takewhile/1,
	 sort_1/1, sort_stable/1, merge/1, rmerge/1, sort_rand/1,
	 usort_1/1, usort_stable/1, umerge/1, rumerge/1,usort_rand/1,
	 keymerge/1, rkeymerge/1,
	 keysort_1/1, keysort_i/1, keysort_stable/1,
	 keysort_rand/1, keysort_error/1,
	 ukeymerge/1, rukeymerge/1,
	 ukeysort_1/1, ukeysort_i/1, ukeysort_stable/1,
	 ukeysort_rand/1, ukeysort_error/1,
	 funmerge/1, rfunmerge/1,
	 funsort_1/1, funsort_stable/1, funsort_rand/1,
	 funsort_error/1,
	 ufunmerge/1, rufunmerge/1,
	 ufunsort_1/1, ufunsort_stable/1, ufunsort_rand/1,
	 ufunsort_error/1,
	 zip_unzip/1, zip_unzip3/1, zipwith/1, zipwith3/1,
	 filter_partition/1, 
	 otp_5939/1, otp_6023/1, otp_6606/1, otp_7230/1,
	 suffix/1, subtract/1, droplast/1, hof/1]).

%% Sort randomized lists until stopped.
%%
%% If you update some of the sort or merge functions, you should
%% definitely let sort_loop work for a couple of hours or days. Try
%% both sort_loop/0 and sort_loop/1 with a small argument (30-50 say).

-export([sort_loop/0, sort_loop/1, sloop/1]).

%% Internal export.
-export([make_fun/1]).

%%
%% all/1
%%
suite() ->
    [{ct_hooks,[ts_install_cth]},
     {timetrap,{minutes,4}}].

all() -> 
    [{group, append},
     {group, key},
     {group,sort},
     {group, usort},
     {group, keysort},
     {group, ukeysort},
     {group, funsort},
     {group, ufunsort},
     {group, sublist},
     {group, flatten},
     {group, seq},
     {group, tickets},
     {group, zip},
     {group, misc}].

groups() -> 
    [{append, [parallel], [append_1, append_2]},
     {usort, [parallel],
      [umerge, rumerge, usort_1, usort_rand, usort_stable]},
     {keysort, [parallel],
      [keymerge, rkeymerge, keysort_1, keysort_rand,
       keysort_i, keysort_stable, keysort_error]},
     {key, [parallel], [keymember, keysearch_keyfind, keystore,
			keytake, keyreplace]},
     {sort,[parallel],[merge, rmerge, sort_1, sort_rand]},
     {ukeysort, [parallel],
      [ukeymerge, rukeymerge, ukeysort_1, ukeysort_rand,
       ukeysort_i, ukeysort_stable, ukeysort_error]},
     {funsort, [parallel],
      [funmerge, rfunmerge, funsort_1, funsort_stable,
       funsort_error, funsort_rand]},
     {ufunsort, [parallel],
      [ufunmerge, rufunmerge, ufunsort_1, ufunsort_stable,
       ufunsort_error, ufunsort_rand]},
     {seq, [parallel], [seq_loop, seq_2, seq_3, seq_2_e, seq_3_e]},
     {sublist, [parallel],
      [sublist_2, sublist_3, sublist_2_e, sublist_3_e]},
     {flatten, [parallel],
      [flatten_1, flatten_2, flatten_1_e, flatten_2_e]},
     {tickets, [parallel], [otp_5939, otp_6023, otp_6606, otp_7230]},
     {zip, [parallel], [zip_unzip, zip_unzip3, zipwith, zipwith3]},
     {misc, [parallel], [reverse, member, dropwhile, takewhile,
			 filter_partition, suffix, subtract,
			 hof]}
    ].

init_per_suite(Config) ->
    Config.

end_per_suite(_Config) ->
    ok.

init_per_group(_GroupName, Config) ->
    Config.

end_per_group(_GroupName, Config) ->
    Config.


init_per_testcase(_Case, Config) ->
    Config.

end_per_testcase(_Case, _Config) ->
    ok.

%
% Test cases starts here.
%

append_1(doc) ->   [];
append_1(suite) -> [];
append_1(Config) when is_list(Config) ->
    ?line "abcdef"=lists:append(["abc","def"]),
    ?line [hej, du,[glade, [bagare]]]=
	lists:append([[hej], [du], [[glade, [bagare]]]]),
    ?line [10, [elem]]=lists:append([[10], [[elem]]]),
    ok.

append_2(doc) ->   [];
append_2(suite) -> [];
append_2(Config) when is_list(Config) ->
    ?line "abcdef"=lists:append("abc", "def"),
    ?line [hej, du]=lists:append([hej], [du]),
    ?line [10, [elem]]=lists:append([10], [[elem]]),
    ok.

reverse(suite) ->
    [];
reverse(doc) ->
    ["Tests the lists:reverse() implementation. The function is "
     "`non-blocking', and only processes a fixed number of elements "
     "at a time."];
reverse(Config) when is_list(Config) ->
    ?line reverse_test(0),
    ?line reverse_test(1),
    ?line reverse_test(2),
    ?line reverse_test(128),
    ?line reverse_test(256),
    ?line reverse_test(1000),
    ?line reverse_test(1998),
    ?line reverse_test(1999),
    ?line reverse_test(2000),
    ?line reverse_test(2001),
    ?line reverse_test(3998),
    ?line reverse_test(3999),
    ?line reverse_test(4000),
    ?line reverse_test(4001),
    ?line reverse_test(60001),
    ?line reverse_test(100007),
    ok.

reverse_test(0) ->
    case lists:reverse([]) of
	[] ->
	    ok;
	_Other ->
	    error
    end;
reverse_test(Num) ->
    List0 = ['The Element'|lists:duplicate(Num, 'Ele')],
    List = lists:reverse(List0),
    ['Ele'|_] = List,
    'The Element' = lists:last(List),
    List0 = lists:reverse(List),
    ok.

member(doc) ->
    ["Tests the lists:member() implementation."
     "This test case depends on lists:reverse() to work, "
     "wich is tested in a separate test case."];
member(Config) when is_list(Config) ->
    ?line {'EXIT',{badarg,_}} = (catch lists:member(45, {a,b,c})),
    ?line {'EXIT',{badarg,_}} = (catch lists:member(45, [0|non_list_tail])),
    ?line false = lists:member(4233, []),
    ?line member_test(1),
    ?line member_test(100),
    ?line member_test(256),
    ?line member_test(1000),
    ?line member_test(1998),
    ?line member_test(1999),
    ?line member_test(2000),
    ?line member_test(2001),
    ?line member_test(3998),
    ?line member_test(3999),
    ?line member_test(4000),
    ?line member_test(4001),
    ?line member_test(100008),
    ok.

member_test(Num) ->
    List0 = ['The Element'|lists:duplicate(Num, 'Elem')],
    true = lists:member('The Element', List0),
    true = lists:member('Elem', List0),
    false = lists:member(arne_anka, List0),
    false = lists:member({a,b,c}, List0),
    List = lists:reverse(List0),
    true = lists:member('The Element', List),
    true = lists:member('Elem', List),
    false = lists:member(arne_anka, List),
    false = lists:member({a,b,c}, List).

keymember(Config) when is_list(Config) ->
    ?line false = lists:keymember(anything_goes, 1, []),
    ?line {'EXIT',{badarg,_}} = (catch lists:keymember(anything_goes, -1, [])),
    ?line {'EXIT',{badarg,_}} = (catch lists:keymember(anything_goes, 0, [])),
    ?line {'EXIT',{badarg,_}} = (catch lists:keymember(anything_goes, 1, {1,2,3})),
    List = [{52.0,a},{-19,b,c},{37.5,d},an_atom,42.0,{39},{45,{x,y,z}}],

    ?line false = lists:keymember(333, 5, List),
    ?line false = lists:keymember(333, 999, List),
    ?line false = lists:keymember(37, 1, List),

    ?line true = lists:keymember(52.0, 1, List),
    ?line true = lists:keymember(52, 1, List),
    ?line true = lists:keymember(-19, 1, List),
    ?line true = lists:keymember(-19.0, 1, List),
    ?line true = lists:keymember(37.5, 1, List),
    ?line true = lists:keymember(39, 1, List),
    ?line true = lists:keymember(39.0, 1, List),
    ?line true = lists:keymember(45, 1, List),
    ?line true = lists:keymember(45.0, 1, List),

    ?line true = lists:keymember(a, 2, List),
    ?line true = lists:keymember(b, 2, List),
    ?line true = lists:keymember(c, 3, List),
    ?line true = lists:keymember(d, 2, List),
    ?line true = lists:keymember({x,y,z}, 2, List),

    ?line Long0 = lists:seq(1, 100007),
    ?line false = lists:keymember(kalle, 1, Long0),
    ?line Long = lists:foldl(fun(E, A) -> [{1/E,E}|A] end, [], Long0),
    ?line true = lists:keymember(1, 2, Long),
    ?line true = lists:keymember(2, 2, Long),
    ?line true = lists:keymember(1.0, 2, Long),
    ?line true = lists:keymember(2.0, 2, Long),
    ?line true = lists:keymember(100006, 2, Long),
    ok.

keysearch_keyfind(Config) when is_list(Config) ->
    ?line false = key_search_find(anything_goes, 1, []),
    ?line {'EXIT',{badarg,_}} = (catch key_search_find(anything_goes, -1, [])),
    ?line {'EXIT',{badarg,_}} = (catch key_search_find(anything_goes, 0, [])),
    ?line {'EXIT',{badarg,_}} = (catch key_search_find(anything_goes, 1, {1,2,3})),

    First = {x,42.0},
    Second = {y,-77},
    Third = {z,[a,b,c],{5.0}},
    List = [First,Second,Third],
    
    ?line false = key_search_find(333, 1, []),
    ?line false = key_search_find(333, 5, List),
    ?line false = key_search_find(333, 999, List),
    ?line false = key_search_find(37, 1, List),

    ?line {value,First} = key_search_find(42, 2, List),
    ?line {value,First} = key_search_find(42.0, 2, List),

    ?line {value,Second} = key_search_find(-77, 2, List),
    ?line {value,Second} = key_search_find(-77.0, 2, List),

    ?line {value,Third} = key_search_find(z, 1, List),
    ?line {value,Third} = key_search_find([a,b,c], 2, List),
    ?line {value,Third} = key_search_find({5}, 3, List),
    ?line {value,Third} = key_search_find({5.0}, 3, List),

    ?line Long0 = lists:seq(1, 100007),
    ?line false = key_search_find(kalle, 1, Long0),
    ?line Long = lists:foldl(fun(E, A) -> [{1/E,float(E)}|A] end, [], Long0),
    ?line {value,{_,1.0}} = key_search_find(1, 2, Long),
    ?line {value,{_,1.0}} = key_search_find(1.0, 2, Long),
    ?line {value,{_,2.0}} = key_search_find(2, 2, Long),
    ?line {value,{_,2.0}} = key_search_find(2.0, 2, Long),
    ?line {value,{_,33988.0}} = key_search_find(33988, 2, Long),
    ?line {value,{_,33988.0}} = key_search_find(33988.0, 2, Long),
    ok.

%% Test both lists:keysearch/3 and lists:keyfind/3. The only
%% difference between these two functions is that lists:keysearch/3
%% wraps a successfully returned tuple in a value tuple.
%%
key_search_find(Key, Pos, List) ->
    case lists:keyfind(Key, Pos, List) of
	false ->
	    false = lists:keysearch(Key, Pos, List);
	Tuple when is_tuple(Tuple) ->
	    {value,Tuple} = lists:keysearch(Key, Pos, List)
    end.

dropwhile(Config) when is_list(Config) ->
    ?line F = fun(C) -> C =:= $@ end,

    ?line [] = lists:dropwhile(F, []),
    ?line [a] = lists:dropwhile(F, [a]),
    ?line [a,b] = lists:dropwhile(F, [a,b]),
    ?line [a,b,c] = lists:dropwhile(F, [a,b,c]),

    ?line [] = lists:dropwhile(F, [$@]),
    ?line [] = lists:dropwhile(F, [$@,$@]),
    ?line [a,$@] = lists:dropwhile(F, [$@,a,$@]),

    ?line [$k] = lists:dropwhile(F, [$@,$k]),
    ?line [$k,$l] = lists:dropwhile(F, [$@,$@,$k,$l]),
    ?line [a] = lists:dropwhile(F, [$@,$@,$@,a]),

    ?line [a,$@,b] = lists:dropwhile(F, [$@,a,$@,b]),
    ?line [a,$@,b] = lists:dropwhile(F, [$@,$@,a,$@,b]),
    ?line [a,$@,b] = lists:dropwhile(F, [$@,$@,$@,a,$@,b]),

    Long = lists:seq(1, 1024),
    Shorter = lists:seq(800, 1024),

    ?line Shorter = lists:dropwhile(fun(E) -> E < 800 end, Long),

    ok.

takewhile(Config) when is_list(Config) ->
    F = fun(C) -> C =/= $@ end,

    [] = lists:takewhile(F, []),
    [a] = lists:takewhile(F, [a]),
    [a,b] = lists:takewhile(F, [a,b]),
    [a,b,c] = lists:takewhile(F, [a,b,c]),

    [] = lists:takewhile(F, [$@]),
    [] = lists:takewhile(F, [$@,$@]),
    [a] = lists:takewhile(F, [a,$@]),

    [$k] = lists:takewhile(F, [$k,$@]),
    [$k,$l] = lists:takewhile(F, [$k,$l,$@,$@]),
    [a] = lists:takewhile(F, [a,$@,$@,$@]),

    [] = lists:takewhile(F, [$@,a,$@,b]),
    [] = lists:takewhile(F, [$@,$@,a,$@,b]),
    [] = lists:takewhile(F, [$@,$@,$@,a,$@,b]),

    Long = lists:seq(1, 1024),
    Shorter = lists:seq(1, 400),

    Shorter = lists:takewhile(fun(E) -> E =< 400 end, Long),

    ok.

keystore(doc) ->
    ["OTP-XXX."];
keystore(suite) -> [];
keystore(Config) when is_list(Config) ->
    ?line {'EXIT',_} = (catch lists:keystore(key, 0, [], {1})),
    ?line {'EXIT',_} = (catch lists:keystore(key, 1, {}, {})),
    ?line {'EXIT',_} = (catch lists:keystore(key, 1, {a,b}, {})),
    ?line {'EXIT', _} = (catch lists:keystore(a, 2, [{1,a}], b)),
    T = {k,17},
    ?line [T] = lists:keystore(a, 2, [], T),
    ?line [{1,a},{2,b},{k,17}] = lists:keystore(c, 2, [{1,a},{2,b}],T),
    L = [{1,a},{2,b},{3,c}],
    ?line [{k,17},{2,b},{3,c}] = lists:keystore(a, 2, L, T),
    ?line [{1,a},{k,17},{3,c}] = lists:keystore(b, 2, L, T),
    ?line [{1,a},{2,b},{k,17}] = lists:keystore(c, 2, L, T),
    ?line [{2,b}] = lists:keystore(a, 2, [{1,a}], {2,b}),
    ?line [{1,a}] = lists:keystore(foo, 1, [], {1,a}),
    ok.

keytake(doc) ->
    ["OTP-XXX."];
keytake(suite) -> [];
keytake(Config) when is_list(Config) ->
    ?line {'EXIT',_} = (catch lists:keytake(key, 0, [])),
    ?line {'EXIT',_} = (catch lists:keytake(key, 1, {})),
    ?line {'EXIT',_} = (catch lists:keytake(key, 1, {a,b})),
    ?line false = lists:keytake(key, 2, [{a}]),
    ?line false = lists:keytake(key, 1, [a]),
    ?line false = lists:keytake(k, 1, []),
    ?line false = lists:keytake(k, 1, [{a},{b},{c}]),
    L = [{a,1},{b,2},{c,3}],
    ?line {value,{a,1},[{b,2},{c,3}]} = lists:keytake(1, 2, L),
    ?line {value,{b,2},[{a,1},{c,3}]} = lists:keytake(2, 2, L),
    ?line {value,{c,3},[{a,1},{b,2}]} = lists:keytake(3, 2, L),
    ?line false = lists:keytake(4, 2, L),
    ok.

%% Test lists:keyreplace/4.
keyreplace(Config) when is_list(Config) ->
    [{new,42}] = lists:keyreplace(k, 1, [{k,1}], {new,42}),
    [atom,{new,a,b}] = lists:keyreplace(k, 1, [atom,{k,1}], {new,a,b}),
    [a,{x,y,z}] = lists:keyreplace(a, 5, [a,{x,y,z}], {no,use}),

    %% Error cases.
    {'EXIT',_} = (catch lists:keyreplace(k, 1, [], not_tuple)),
    {'EXIT',_} = (catch lists:keyreplace(k, 0, [], {a,b})),
    ok.

merge(doc) ->   ["merge functions"];
merge(suite) -> [];
merge(Config) when is_list(Config) ->

    %% merge list of lists
    ?line [] = lists:merge([]),
    ?line [] = lists:merge([[]]),
    ?line [] = lists:merge([[],[]]),
    ?line [] = lists:merge([[],[],[]]),
    ?line [1] = lists:merge([[1]]),
    ?line [1,1,2,2] = lists:merge([[1,2],[1,2]]),
    ?line [1] = lists:merge([[1],[],[]]),
    ?line [1] = lists:merge([[],[1],[]]),
    ?line [1] = lists:merge([[],[],[1]]),
    ?line [1,2] = lists:merge([[1],[2],[]]),
    ?line [1,2] = lists:merge([[1],[],[2]]),
    ?line [1,2] = lists:merge([[],[1],[2]]),
    ?line [1,2,3,4,5,6] = lists:merge([[1,2],[],[5,6],[],[3,4],[]]),
    ?line [1,2,3,4] = lists:merge([[4],[3],[2],[1]]),
    ?line [1,2,3,4,5] = lists:merge([[1],[2],[3],[4],[5]]),
    ?line [1,2,3,4,5,6] = lists:merge([[1],[2],[3],[4],[5],[6]]),
    ?line [1,2,3,4,5,6,7,8,9] = 
	lists:merge([[1],[2],[3],[4],[5],[6],[7],[8],[9]]),
    Seq = lists:seq(1,100),
    ?line true = Seq == lists:merge(lists:map(fun(E) -> [E] end, Seq)),

    Two = [1,2],
    Six = [1,2,3,4,5,6],

    %% 2-way merge
    ?line [] = lists:merge([], []),
    ?line Two = lists:merge(Two, []),
    ?line Two = lists:merge([], Two),
    ?line Six = lists:merge([1,3,5], [2,4,6]),
    ?line Six = lists:merge([2,4,6], [1,3,5]),
    ?line Six = lists:merge([1,2,3], [4,5,6]),
    ?line Six = lists:merge([4,5,6], [1,2,3]),
    ?line Six = lists:merge([1,2,5],[3,4,6]),
    ?line [1,2,3,5,7] = lists:merge([1,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:merge([1,3,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:merge([1,3,5,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:merge([2], [1,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:merge([2,4], [1,3,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:merge([2,4,6], [1,3,5,7]),

    %% 3-way merge
    ?line [] = lists:merge3([], [], []),
    ?line Two = lists:merge3([], [], Two),
    ?line Two = lists:merge3([], Two, []),
    ?line Two = lists:merge3(Two, [], []),
    ?line Six = lists:merge3([], [1,3,5], [2,4,6]),
    ?line Six = lists:merge3([1,3,5], [], [2,4,6]),
    ?line Six = lists:merge3([1,3,5], [2,4,6], []),
    ?line Nine = lists:merge3([1,4,7],[2,5,8],[3,6,9]),
    ?line Nine = lists:merge3([1,4,7],[3,6,9],[2,5,8]),
    ?line Nine = lists:merge3([3,6,9],[1,4,7],[2,5,8]),
    ?line Nine = lists:merge3([4,5,6],[1,2,3],[7,8,9]),
    ?line Nine = lists:merge3([1,2,3],[4,5,6],[7,8,9]),
    ?line Nine = lists:merge3([7,8,9],[4,5,6],[1,2,3]),
    ?line Nine = lists:merge3([4,5,6],[7,8,9],[1,2,3]),

    ok.

rmerge(doc) ->   ["reverse merge functions"];
rmerge(suite) -> [];
rmerge(Config) when is_list(Config) ->

    Two = [2,1],
    Six = [6,5,4,3,2,1],

    %% 2-way reversed merge
    ?line [] = lists:rmerge([], []),
    ?line Two = lists:rmerge(Two, []),
    ?line Two = lists:rmerge([], Two),
    ?line Six = lists:rmerge([5,3,1], [6,4,2]),
    ?line Six = lists:rmerge([6,4,2], [5,3,1]),
    ?line Six = lists:rmerge([3,2,1], [6,5,4]),
    ?line Six = lists:rmerge([6,5,4], [3,2,1]),
    ?line Six = lists:rmerge([4,3,2],[6,5,1]),
    ?line [7,6,5,3,1] = lists:rmerge([7,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rmerge([7,5,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rmerge([7,5,3,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rmerge([2], [7,5,3,1]),
    ?line [7,5,4,3,2,1] = lists:rmerge([4,2], [7,5,3,1]),
    ?line [7,6,5,4,3,2,1] = lists:rmerge([6,4,2], [7,5,3,1]),

    Nine = [9,8,7,6,5,4,3,2,1],

    %% 3-way reversed merge
    ?line [] = lists:rmerge3([], [], []),
    ?line Two = lists:rmerge3([], [], Two),
    ?line Two = lists:rmerge3([], Two, []),
    ?line Two = lists:rmerge3(Two, [], []),
    ?line Six = lists:rmerge3([], [5,3,1], [6,4,2]),
    ?line Six = lists:rmerge3([5,3,1], [], [6,4,2]),
    ?line Six = lists:rmerge3([5,3,1], [6,4,2], []),
    ?line Nine = lists:rmerge3([7,4,1],[8,5,2],[9,6,3]),
    ?line Nine = lists:rmerge3([7,4,1],[9,6,3],[8,5,2]),
    ?line Nine = lists:rmerge3([9,6,3],[7,4,1],[8,5,2]),
    ?line Nine = lists:rmerge3([6,5,4],[3,2,1],[9,8,7]),
    ?line Nine = lists:rmerge3([3,2,1],[6,5,4],[9,8,7]),
    ?line Nine = lists:rmerge3([9,8,7],[6,5,4],[3,2,1]),
    ?line Nine = lists:rmerge3([6,5,4],[9,8,7],[3,2,1]),

    ok.

sort_1(doc) ->   ["sort/1"];
sort_1(suite) -> [];
sort_1(Config) when is_list(Config) ->
    ?line [] = lists:sort([]),
    ?line [a] = lists:sort([a]),
    ?line [a,a] = lists:sort([a,a]),
    ?line [a,b] = lists:sort([a,b]),
    ?line [a,b] = lists:sort([b,a]),
    ?line [1,1] = lists:sort([1,1]),
    ?line [1,1,2,3] = lists:sort([1,1,3,2]),
    ?line [1,2,3,3] = lists:sort([3,3,1,2]),
    ?line [1,1,1,1] = lists:sort([1,1,1,1]),
    ?line [1,1,1,2,2,2,3,3,3] = lists:sort([3,3,3,2,2,2,1,1,1]),
    ?line [1,1,1,2,2,2,3,3,3] = lists:sort([1,1,1,2,2,2,3,3,3]),

    ?line lists:foreach(fun check/1, perms([1,2,3])),
    ?line lists:foreach(fun check/1, perms([1,2,3,4,5,6,7,8])),
    ok.

sort_rand(doc) ->   ["sort/1 on big randomized lists"];
sort_rand(suite) -> [];
sort_rand(Config) when is_list(Config) ->
    ?line ok = check(biglist(10)),
    ?line ok = check(biglist(100)),
    ?line ok = check(biglist(1000)),
    ?line ok = check(biglist(10000)),
    ok.

%% sort/1 was really stable for a while - the order of equal elements
%% was kept - but since the performance suffered a bit, this "feature"
%% was removed.
sort_stable(doc) ->   ["sort/1 should be stable for equal terms."];
sort_stable(suite) -> [];
sort_stable(Config) when is_list(Config) ->
    ?line ok = check_stability(bigfunlist(10)),
    ?line ok = check_stability(bigfunlist(100)),
    ?line ok = check_stability(bigfunlist(1000)),
    ?line case erlang:system_info(modified_timing_level) of
              undefined -> ok = check_stability(bigfunlist(10000));
              _ -> ok
          end,
    ok.

check([]) ->
    ok;
check(L) ->
    S = lists:sort(L),
    case {length(L) == length(S), check(hd(S), tl(S))} of
	{true,ok} ->
	    ok;
	_ ->
	    io:format("~w~n", [L]),
	    erlang:error(check)
    end.

check(_A, []) ->
    ok;
check(A, [B | L]) when A =< B ->
    check(B, L);
check(_A, _L) ->
    no.

%% The check that sort/1 is stable is no longer used.
%% Equal elements are no longer always kept in order.
check_stability(L) ->
    S = lists:sort(L),
    LP = explicit_pid(L),
    SP = explicit_pid(S),
    check_sorted(1, 2, LP, SP).

explicit_pid(L) ->
    lists:reverse(expl_pid(L, [])).

expl_pid([{I,F} | T], L) when is_function(F) ->
    expl_pid(T, [{I,fun_pid(F)} | L]);
expl_pid([], L) ->
    L.


usort_1(suite) -> [];
usort_1(doc) -> [""];
usort_1(Conf) when is_list(Conf) ->
    ?line [] = lists:usort([]),
    ?line [1] = lists:usort([1]), 
    ?line [1] = lists:usort([1,1]),
    ?line [1] = lists:usort([1,1,1,1,1]),
    ?line [1,2] = lists:usort([1,2]),
    ?line [1,2] = lists:usort([1,2,1]),
    ?line [1,2] = lists:usort([1,2,2]),
    ?line [1,2,3] = lists:usort([1,3,2]),
    ?line [1,3] = lists:usort([3,1,3]),
    ?line [0,1,3] = lists:usort([3,1,0]),
    ?line [1,2,3] = lists:usort([3,1,2]),
    ?line [1,2] = lists:usort([2,1,1]),
    ?line [1,2] = lists:usort([2,1]),
    ?line [0,3,4,8,9] = lists:usort([3,8,9,0,9,4]),

    ?line lists:foreach(fun ucheck/1, perms([1,2,3])),
    ?line lists:foreach(fun ucheck/1, perms([1,2,3,4,5,6,2,1])),

    ok.

umerge(suite) -> [];
umerge(doc) -> [""];
umerge(Conf) when is_list(Conf) ->
    %% merge list of lists
    ?line [] = lists:umerge([]),
    ?line [] = lists:umerge([[]]),
    ?line [] = lists:umerge([[],[]]),
    ?line [] = lists:umerge([[],[],[]]),
    ?line [1] = lists:umerge([[1]]),
    ?line [1,2] = lists:umerge([[1,2],[1,2]]),
    ?line [1] = lists:umerge([[1],[],[]]),
    ?line [1] = lists:umerge([[],[1],[]]),
    ?line [1] = lists:umerge([[],[],[1]]),
    ?line [1,2] = lists:umerge([[1],[2],[]]),
    ?line [1,2] = lists:umerge([[1],[],[2]]),
    ?line [1,2] = lists:umerge([[],[1],[2]]),
    ?line [1,2,3,4,5,6] = lists:umerge([[1,2],[],[5,6],[],[3,4],[]]),
    ?line [1,2,3,4] = lists:umerge([[4],[3],[2],[1]]),
    ?line [1,2,3,4,5] = lists:umerge([[1],[2],[3],[4],[5]]),
    ?line [1,2,3,4,5,6] = lists:umerge([[1],[2],[3],[4],[5],[6]]),
    ?line [1,2,3,4,5,6,7,8,9] = 
        lists:umerge([[1],[2],[3],[4],[5],[6],[7],[8],[9]]),
    ?line [1,2,4,6,8] = lists:umerge([[1,2],[2,4,6,8]]),
    Seq = lists:seq(1,100),
    ?line true = Seq == lists:umerge(lists:map(fun(E) -> [E] end, Seq)),

    Two = [1,2],
    Six = [1,2,3,4,5,6],

    %% 2-way unique merge
    ?line [] = lists:umerge([], []),
    ?line Two = lists:umerge(Two, []),
    ?line Two = lists:umerge([], Two),
    ?line Six = lists:umerge([1,3,5], [2,4,6]),
    ?line Six = lists:umerge([2,4,6], [1,3,5]),
    ?line Six = lists:umerge([1,2,3], [4,5,6]),
    ?line Six = lists:umerge([4,5,6], [1,2,3]),
    ?line Six = lists:umerge([1,2,5],[3,4,6]),
    ?line [1,2,3,5,7] = lists:umerge([1,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:umerge([1,3,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:umerge([1,3,5,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:umerge([2], [1,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:umerge([2,4], [1,3,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:umerge([2,4,6], [1,3,5,7]),

    ?line [1,2,3,5,7] = lists:umerge([1,2,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:umerge([1,2,3,4,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:umerge([1,2,3,4,5,6,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:umerge([2], [1,2,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:umerge([2,4], [1,2,3,4,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:umerge([2,4,6], [1,2,3,4,5,6,7]),

    %% 3-way unique merge
    ?line [] = lists:umerge3([], [], []),
    ?line Two = lists:umerge3([], [], Two),
    ?line Two = lists:umerge3([], Two, []),
    ?line Two = lists:umerge3(Two, [], []),
    ?line Six = lists:umerge3([], [1,3,5], [2,4,6]),
    ?line Six = lists:umerge3([1,3,5], [], [2,4,6]),
    ?line Six = lists:umerge3([1,3,5], [2,4,6], []),
    ?line Nine = lists:umerge3([1,4,7],[2,5,8],[3,6,9]),
    ?line Nine = lists:umerge3([1,4,7],[3,6,9],[2,5,8]),
    ?line Nine = lists:umerge3([3,6,9],[1,4,7],[2,5,8]),
    ?line Nine = lists:umerge3([4,5,6],[1,2,3],[7,8,9]),
    ?line Nine = lists:umerge3([1,2,3],[4,5,6],[7,8,9]),
    ?line Nine = lists:umerge3([7,8,9],[4,5,6],[1,2,3]),
    ?line Nine = lists:umerge3([4,5,6],[7,8,9],[1,2,3]),

    ?line [1,2,3] = lists:umerge3([1,2,3],[1,2,3],[1,2,3]),
    ?line [1,2,3,4] = lists:umerge3([2,3,4],[1,2,3],[2,3,4]),
    ?line [1,2,3] = lists:umerge3([1,2,3],[2,3],[1,2,3]),
    ?line [1,2,3,4] = lists:umerge3([2,3,4],[3,4],[1,2,3]),

    ok.

rumerge(suite) -> [];
rumerge(doc) -> [""];
rumerge(Conf) when is_list(Conf) ->
    Two = [2,1],
    Six = [6,5,4,3,2,1],

    %% 2-way reversed unique merge
    ?line [] = lists:rumerge([], []),
    ?line Two = lists:rumerge(Two, []),
    ?line Two = lists:rumerge([], Two),
    ?line Six = lists:rumerge([5,3,1], [6,4,2]),
    ?line Six = lists:rumerge([6,4,2], [5,3,1]),
    ?line Six = lists:rumerge([3,2,1], [6,5,4]),
    ?line Six = lists:rumerge([6,5,4], [3,2,1]),
    ?line Six = lists:rumerge([4,3,2],[6,5,1]),
    ?line [7,6,5,3,1] = lists:rumerge([7,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rumerge([7,5,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge([7,5,3,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rumerge([2], [7,5,3,1]),
    ?line [7,5,4,3,2,1] = lists:rumerge([4,2], [7,5,3,1]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge([6,4,2], [7,5,3,1]),

    ?line [7,6,5,3,1] = lists:rumerge([7,6,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rumerge([7,6,5,4,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge([7,6,5,4,3,2,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rumerge([2], [7,5,3,2,1]),
    ?line [7,5,4,3,2,1] = lists:rumerge([4,2], [7,5,4,3,2,1]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge([6,4,2], [7,6,5,4,3,2,1]),

    Nine = [9,8,7,6,5,4,3,2,1],

    %% 3-way reversed unique merge
    ?line [] = lists:rumerge3([], [], []),
    ?line Two = lists:rumerge3([], [], Two),
    ?line Two = lists:rumerge3([], Two, []),
    ?line Two = lists:rumerge3(Two, [], []),
    ?line Six = lists:rumerge3([], [5,3,1], [6,4,2]),
    ?line Six = lists:rumerge3([5,3,1], [], [6,4,2]),
    ?line Six = lists:rumerge3([5,3,1], [6,4,2], []),
    ?line Nine = lists:rumerge3([7,4,1],[8,5,2],[9,6,3]),
    ?line Nine = lists:rumerge3([7,4,1],[9,6,3],[8,5,2]),
    ?line Nine = lists:rumerge3([9,6,3],[7,4,1],[8,5,2]),
    ?line Nine = lists:rumerge3([6,5,4],[3,2,1],[9,8,7]),
    ?line Nine = lists:rumerge3([3,2,1],[6,5,4],[9,8,7]),
    ?line Nine = lists:rumerge3([9,8,7],[6,5,4],[3,2,1]),
    ?line Nine = lists:rumerge3([6,5,4],[9,8,7],[3,2,1]),

    ?line [3,2,1] = lists:rumerge3([3,2,1],[3,2,1],[3,2,1]),
    ?line [4,3,2,1] = lists:rumerge3([4,3,2],[3,2,1],[3,2,1]),
    ?line [5,4,3,2,1] = lists:rumerge3([4,3,2],[5,4,3,2],[5,4,3,2,1]),
    ?line [6,5,4,3,2] = lists:rumerge3([4,3,2],[5,4,3,2],[6,5,4,3]),

    L1 = [c,d,e],
    L2 = [b,c,d],
    ?line true = 
	lists:umerge(L1, L2) == 
	lists:reverse(lists:rumerge(lists:reverse(L1), lists:reverse(L2))),
    ok.

usort_rand(doc) ->   ["usort/1 on big randomized lists"];
usort_rand(suite) -> [];
usort_rand(Config) when is_list(Config) ->
    ?line ok = ucheck(biglist(10)),
    ?line ok = ucheck(biglist(100)),
    ?line ok = ucheck(biglist(1000)),
    ?line ok = ucheck(biglist(10000)),

    ?line ok = ucheck(ubiglist(10)),
    ?line ok = ucheck(ubiglist(100)),
    ?line ok = ucheck(ubiglist(1000)),
    ?line ok = ucheck(ubiglist(10000)),
    ok.

usort_stable(doc) ->   ["usort/1 should keep the first duplicate."];
usort_stable(suite) -> [];
usort_stable(Config) when is_list(Config) ->
    ?line ok = ucheck_stability(bigfunlist(3)),
    ?line ok = ucheck_stability(bigfunlist(10)),
    ?line ok = ucheck_stability(bigfunlist(100)),
    ?line ok = ucheck_stability(bigfunlist(1000)),
    ?line case erlang:system_info(modified_timing_level) of
              undefined -> ok = ucheck_stability(bigfunlist(10000));
              _ -> ok
          end,
    ok.

ucheck([]) ->
    ok;
ucheck(L) ->
    S = lists:usort(L),
    case ucheck(hd(S), tl(S)) of
	ok ->
	    ok;
	_ ->
	    io:format("~w~n", [L]),
	    erlang:error(ucheck)
    end.

ucheck(_A, []) ->
    ok;
ucheck(A, [B | L]) when A < B ->
    ucheck(B, L);
ucheck(_A, _L) ->
    no.

%% Check that usort/1 is stable and correct relative ukeysort/2.
ucheck_stability(L) ->
    S = no_dups(lsort(L)),
    U = lists:usort(L),
    check_stab(L, U, S, "usort/1", "ukeysort/2").


keymerge(doc) -> ["Key merge two lists."];
keymerge(suite) -> [];
keymerge(Config) when is_list(Config) ->

    Two = [{1,a},{2,b}],
    Six = [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f}],

    %% 2-way keymerge
    ?line [] = lists:keymerge(1, [], []),
    ?line Two = lists:keymerge(1, Two, []),
    ?line Two = lists:keymerge(1, [], Two),
    ?line Six = lists:keymerge(1, [{1,a},{3,c},{5,e}], [{2,b},{4,d},{6,f}]),
    ?line Six = lists:keymerge(1, [{2,b},{4,d},{6,f}], [{1,a},{3,c},{5,e}]),
    ?line Six = lists:keymerge(1, [{1,a},{2,b},{3,c}], [{4,d},{5,e},{6,f}]),
    ?line Six = lists:keymerge(1, [{4,d},{5,e},{6,f}], [{1,a},{2,b},{3,c}]),
    ?line Six = lists:keymerge(1, [{1,a},{2,b},{5,e}],[{3,c},{4,d},{6,f}]),
    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:keymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:keymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b},{4,d}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:keymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b},{4,d},{6,f}]),
    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:keymerge(1, [{2,b}], [{1,a},{3,c},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:keymerge(1, [{2,b},{4,d}], [{1,a},{3,c},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:keymerge(1, [{2,b},{4,d},{6,f}], [{1,a},{3,c},{5,e},{7,g}]),

    ?line [{b,2},{c,11},{c,12},{c,21},{c,22},{e,5}] =
	lists:keymerge(1,[{c,11},{c,12},{e,5}], [{b,2},{c,21},{c,22}]),

    ok.

rkeymerge(doc) -> ["Reverse key merge two lists."];
rkeymerge(suite) -> [];
rkeymerge(Config) when is_list(Config) ->

    Two = [{2,b},{1,a}],
    Six = [{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}],

    %% 2-way reversed keymerge
    ?line [] = lists:rkeymerge(1, [], []),
    ?line Two = lists:rkeymerge(1, Two, []),
    ?line Two = lists:rkeymerge(1, [], Two),
    ?line Six = lists:rkeymerge(1, [{5,e},{3,c},{1,a}], [{6,f},{4,d},{2,b}]),
    ?line Six = lists:rkeymerge(1, [{6,f},{4,d},{2,b}], [{5,e},{3,c},{1,a}]),
    ?line Six = lists:rkeymerge(1, [{3,c},{2,b},{1,a}], [{6,f},{5,e},{4,d}]),
    ?line Six = lists:rkeymerge(1, [{6,f},{5,e},{4,d}], [{3,c},{2,b},{1,a}]),
    ?line Six = lists:rkeymerge(1, [{4,d},{3,c},{2,b}],[{6,f},{5,e},{1,a}]),
    ?line [{7,g},{6,f},{5,e},{3,c},{1,a}] = 
	lists:rkeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{1,a}] = 
	lists:rkeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f},{4,d}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rkeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f},{4,d},{2,b}]),
    ?line [{7,g},{5,e},{3,c},{2,b},{1,a}] = 
	lists:rkeymerge(1, [{2,b}], [{7,g},{5,e},{3,c},{1,a}]),
    ?line [{7,g},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rkeymerge(1, [{4,d},{2,b}], [{7,g},{5,e},{3,c},{1,a}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rkeymerge(1, [{6,f},{4,d},{2,b}], [{7,g},{5,e},{3,c},{1,a}]),

    L1 = [{c,11},{c,12},{e,5}],
    L2 = [{b,2},{c,21},{c,22}],
    ?line true = 
	lists:keymerge(1, L1, L2) == 
	lists:reverse(lists:rkeymerge(1,lists:reverse(L1), 
				      lists:reverse(L2))),

    ok.

keysort_1(doc) ->   ["keysort"];
keysort_1(suite) -> [];
keysort_1(Config) when is_list(Config) ->
    ?line ok = keysort_check(1, [], []),
    ?line ok = keysort_check(1, [{a,b}], [{a,b}]),
    ?line ok = keysort_check(1, [{a,b},{a,b}], [{a,b},{a,b}]),
    ?line ok = keysort_check(1, [{a,b},{b,c}], [{a,b},{b,c}]),
    ?line ok = keysort_check(1, [{b,c},{a,b}], [{a,b},{b,c}]),
    ?line ok = keysort_check(1,
			     [{1,e},{3,f},{2,y},{0,z},{x,14}],
			     [{0,z},{1,e},{2,y},{3,f},{x,14}]),
    ?line ok = keysort_check(1,
			     [{1,a},{1,a},{1,a},{1,a}],
			     [{1,a},{1,a},{1,a},{1,a}]),

    ?line [{b,1},{c,1}] = lists:keysort(1, [{c,1},{b,1}]),
    ?line [{a,0},{b,2},{c,3},{d,4}] = 
	  lists:keysort(1, [{d,4},{c,3},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{b,2},{c,1}] =
	  lists:keysort(1, [{c,1},{b,1},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{b,2},{c,1},{d,4}] =
	  lists:keysort(1, [{c,1},{b,1},{b,2},{a,0},{d,4}]),

    SFun = fun(L) -> fun(X) -> keysort_check(1, X, L) end end,
    L1 = [{1,a},{2,b},{3,c}],
    ?line lists:foreach(SFun(L1), perms(L1)),
    L2 = [{1,a},{1,a},{2,b}],
    ?line lists:foreach(SFun(L2), perms(L2)),
    L3 = [{1,a},{1,a},{1,a},{2,b}],
    ?line lists:foreach(SFun(L3), perms(L3)),
    L4 = [{a,1},{a,1},{b,2},{b,2},{c,3},{d,4},{e,5},{f,6}],
    ?line lists:foreach(SFun(L4), perms(L4)),

    ok.

keysort_stable(doc) ->   ["keysort should be stable"];
keysort_stable(suite) -> [];
keysort_stable(Config) when is_list(Config) ->
    ?line ok = keysort_check(1, [{1,b},{1,c}], [{1,b},{1,c}]),
    ?line ok = keysort_check(1, [{1,c},{1,b}], [{1,c},{1,b}]),
    ?line ok = keysort_check(1,
			     [{1,c},{1,b},{2,x},{3,p},{2,a}],
			     [{1,c},{1,b},{2,x},{2,a},{3,p}]),
    ?line ok = keysort_check(1, 
			     [{1,a},{1,b},{1,a},{1,a}],
			     [{1,a},{1,b},{1,a},{1,a}]),
    ok.

keysort_error(doc) ->   ["keysort should exit when given bad arguments"];
keysort_error(suite) -> [];
keysort_error(Config) when is_list(Config) ->
    ?line {'EXIT', _} = (catch lists:keysort(0, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:keysort(3, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:keysort(1.5, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:keysort(x, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:keysort(x, [])),
    ?line {'EXIT', _} = (catch lists:keysort(x, [{1,b}])),
    ?line {'EXIT', _} = (catch lists:keysort(1, [a,b])),
    ?line {'EXIT', _} = (catch lists:keysort(1, [{1,b} | {1,c}])),
    ok.

keysort_i(doc) ->   ["keysort with other key than first element"];
keysort_i(suite) -> [];
keysort_i(Config) when is_list(Config) ->
    ?line ok = keysort_check(2, [{a,2},{b,1},{c,3}], [{b,1},{a,2},{c,3}]),
    ok.

keysort_rand(doc) ->   ["keysort on big randomized lists"];
keysort_rand(suite) -> [];
keysort_rand(Config) when is_list(Config) ->
    ?line ok = keysort_check3(1, biglist(10)),
    ?line ok = keysort_check3(1, biglist(100)),
    ?line ok = keysort_check3(1, biglist(1000)),
    ?line ok = keysort_check3(1, biglist(10000)),

    ?line ok = keysort_check3(2, biglist(10)),
    ?line ok = keysort_check3(2, biglist(100)),
    ?line ok = keysort_check3(2, biglist(1000)),
    ?line ok = keysort_check3(2, biglist(10000)),
    ok.

%%% Keysort a list, check that the returned list is what we expected,
%%% and that it is actually sorted.
keysort_check(I, Input, Expected) ->
    ?line Expected = lists:keysort(I, Input),
    check_sorted(I, Input, Expected).

keysort_check3(I, Input) ->
    check_sorted(I, 3, Input, lists:keysort(I, Input)).

check_sorted(I, Input, L) ->
    check_sorted(I, I, Input, L).

%%% Check that a list is keysorted by element I. Elements comparing equal
%%% should be sorted according to element J.
check_sorted(_I, _J, _Input, []) ->
    ok;
check_sorted(I, J, Input, [A | Rest]) ->
    case catch check_sorted1(I, J, A, Rest) of
	{'EXIT', _} ->
	    io:format("~w~n", [Input]),
	    erlang:error(check_sorted);
	Reply ->
	    Reply
    end.

check_sorted1(_I, _J, _A, []) ->
    ok;
check_sorted1(I, J, A, [B | Rest]) ->
    ok = keycompare(I, J, A, B),
    check_sorted1(I, J, B, Rest).

keycompare(I, _J, A, B) when element(I, A) < element(I, B) ->
    ok;
keycompare(I, J, A, B) when element(I, A) == element(I, B), 
			    element(J, A) =< element(J, B) ->
    ok.


ukeymerge(suite) -> [];
ukeymerge(doc) -> ["Merge two lists while removing duplicates."];
ukeymerge(Conf) when is_list(Conf) ->

    Two = [{1,a},{2,b}],
    Six = [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f}],

    %% 2-way unique keymerge
    ?line [] = lists:ukeymerge(1, [], []),
    ?line Two = lists:ukeymerge(1, Two, []),
    ?line Two = lists:ukeymerge(1, [], Two),
    ?line [] = lists:ukeymerge(1, [], []),
    ?line Two = lists:ukeymerge(1, Two, []),
    ?line Two = lists:ukeymerge(1, [], Two),
    ?line Six = lists:ukeymerge(1, [{1,a},{3,c},{5,e}], [{2,b},{4,d},{6,f}]),
    ?line Six = lists:ukeymerge(1, [{2,b},{4,d},{6,f}], [{1,a},{3,c},{5,e}]),
    ?line Six = lists:ukeymerge(1, [{1,a},{2,b},{3,c}], [{4,d},{5,e},{6,f}]),
    ?line Six = lists:ukeymerge(1, [{4,d},{5,e},{6,f}], [{1,a},{2,b},{3,c}]),
    ?line Six = lists:ukeymerge(1, [{1,a},{2,b},{5,e}],[{3,c},{4,d},{6,f}]),
    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b},{4,d}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{3,c},{5,e},{7,g}], [{2,b},{4,d},{6,f}]),
    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{2,b}], [{1,a},{3,c},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{2,b},{4,d}], [{1,a},{3,c},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:ukeymerge(1, [{2,b},{4,d},{6,f}], [{1,a},{3,c},{5,e},{7,g}]),

    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{2,b},{3,c},{5,e},{7,g}], [{2,b}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}], 
			[{2,b},{4,d}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:ukeymerge(1, [{1,a},{3,c},{5,e},{6,f},{7,g}], 
			[{2,b},{4,d},{6,f}]),
    ?line [{1,a},{2,b},{3,c},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{2,b}], [{1,a},{2,b},{3,c},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}] = 
	lists:ukeymerge(1, [{2,b},{4,d}], 
			[{1,a},{2,b},{3,c},{4,d},{5,e},{7,g}]),
    ?line [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}] = 
	lists:ukeymerge(1, [{2,b},{4,d},{6,f}], 
		     [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{7,g}]),

    L1 = [{a,1},{a,3},{a,5},{a,7}],
    L2 = [{b,1},{b,3},{b,5},{b,7}],
    ?line L1 = lists:ukeymerge(2, L1, L2),

    ok.

rukeymerge(suite) -> [];
rukeymerge(doc) -> 
    ["Reverse merge two lists while removing duplicates."];
rukeymerge(Conf) when is_list(Conf) ->

    Two = [{2,b},{1,a}],
    Six = [{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}],

    %% 2-way reversed unique keymerge
    ?line [] = lists:rukeymerge(1, [], []),
    ?line Two = lists:rukeymerge(1, Two, []),
    ?line Two = lists:rukeymerge(1, [], Two),
    ?line Six = lists:rukeymerge(1, [{5,e},{3,c},{1,a}], [{6,f},{4,d},{2,b}]),
    ?line Six = lists:rukeymerge(1, [{6,f},{4,d},{2,b}], [{5,e},{3,c},{1,a}]),
    ?line Six = lists:rukeymerge(1, [{3,c},{2,b},{1,a}], [{6,f},{5,e},{4,d}]),
    ?line Six = lists:rukeymerge(1, [{6,f},{5,e},{4,d}], [{3,c},{2,b},{1,a}]),
    ?line Six = lists:rukeymerge(1, [{4,d},{3,c},{2,b}],[{6,f},{5,e},{1,a}]),
    ?line [{7,g},{6,f},{5,e},{3,c},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f},{4,d}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{5,e},{3,c},{1,a}], [{6,f},{4,d},{2,b}]),
    ?line [{7,g},{5,e},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{2,b}], [{7,g},{5,e},{3,c},{1,a}]),
    ?line [{7,g},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{4,d},{2,b}], [{7,g},{5,e},{3,c},{1,a}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{6,f},{4,d},{2,b}], [{7,g},{5,e},{3,c},{1,a}]),

    ?line [{7,g},{6,f},{5,e},{3,c},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{6,f},{5,e},{3,c},{1,a}], [{6,f}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{6,f},{5,e},{4,d},{3,c},{1,a}], 
			 [{6,f},{4,d}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}], 
		      [{6,f},{4,d},{2,b}]),
    ?line [{7,g},{5,e},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{2,b}], [{7,g},{5,e},{3,c},{2,b},{1,a}]),
    ?line [{7,g},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{4,d},{2,b}], 
			 [{7,g},{5,e},{4,d},{3,c},{2,b},{1,a}]),
    ?line [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}] = 
	lists:rukeymerge(1, [{6,f},{4,d},{2,b}], 
		      [{7,g},{6,f},{5,e},{4,d},{3,c},{2,b},{1,a}]),

    L1 = [{a,1},{a,3},{a,5},{a,7}],
    L2 = [{b,1},{b,3},{b,5},{b,7}],
    ?line true = 
	lists:ukeymerge(2, L1, L2) == 
	lists:reverse(lists:rukeymerge(2, lists:reverse(L1), 
				       lists:reverse(L2))),

    ok.

ukeysort_1(doc) ->   ["ukeysort"];
ukeysort_1(suite) -> [];
ukeysort_1(Config) when is_list(Config) ->
    ?line ok = ukeysort_check(1, [], []),
    ?line ok = ukeysort_check(1, [{a,b}], [{a,b}]),
    ?line ok = ukeysort_check(1, [{a,b},{a,b}], [{a,b}]),
    ?line ok = ukeysort_check(1, [{a,b},{b,c}], [{a,b},{b,c}]),
    ?line ok = ukeysort_check(1, [{b,c},{a,b}], [{a,b},{b,c}]),
    ?line ok = ukeysort_check(1,
                              [{1,e},{3,f},{2,y},{0,z},{x,14}],
                              [{0,z},{1,e},{2,y},{3,f},{x,14}]),
    ?line ok = ukeysort_check(1, [{1,a},{1,a},{1,a},{1,a}], [{1,a}]),

    L1 = [{1,a},{1,b},{1,a}],
    L1u = lists:ukeysort(1, L1),
    L2 = [{1,a},{1,b},{1,a}],
    L2u = lists:ukeysort(1, L2),
    ?line ok = ukeysort_check(1, lists:keymerge(1, L1, L2), 
                              lists:ukeymerge(1, L1u, L2u)),
    L3 = [{1,a},{1,b},{1,a},{2,a}],
    L3u = lists:ukeysort(1, L3),
    ?line ok = ukeysort_check(1, lists:keymerge(1, L3, L2), 
                              lists:ukeymerge(1, L3u, L2u)),
    L4 = [{1,b},{1,a}],
    L4u = lists:ukeysort(1, L4),
    ?line ok = ukeysort_check(1, lists:keymerge(1, L1, L4), 
                              lists:ukeymerge(1, L1u, L4u)),
    L5 = [{1,a},{1,b},{1,a},{2,a}],
    L5u = lists:ukeysort(1, L5),
    ?line ok = ukeysort_check(1, lists:keymerge(1, [], L5), 
                              lists:ukeymerge(1, [], L5u)),
    ?line ok = ukeysort_check(1, lists:keymerge(1, L5, []), 
                              lists:ukeymerge(1, L5u, [])),
    L6 = [{3,a}],
    L6u = lists:ukeysort(1, L6),
    ?line ok = ukeysort_check(1, lists:keymerge(1, L5, L6), 
                              lists:ukeymerge(1, L5u, L6u)),

    ?line [{b,1},{c,1}] = lists:ukeysort(1, [{c,1},{c,1},{c,1},{c,1},{b,1}]),
    ?line [{a,0},{b,2},{c,3},{d,4}] = 
	  lists:ukeysort(1, [{d,4},{c,3},{b,2},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{c,1}] =
	  lists:ukeysort(1, [{c,1},{b,1},{b,1},{b,2},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{c,1},{d,4}] =
	  lists:ukeysort(1, [{c,1},{b,1},{b,2},{a,0},{a,0},{d,4},{d,4}]),

    SFun = fun(L) -> fun(X) -> ukeysort_check(2, X, L) end end,
    PL = [{a,1},{b,2},{c,3},{d,4},{e,5},{f,6}],
    Ps = perms([{a,1},{b,2},{c,3},{d,4},{e,5},{f,6},{b,2},{a,1}]),
    ?line lists:foreach(SFun(PL), Ps),

    M1L = [{1,a},{1,a},{2,b}],
    M1s = [{1,a},{2,b}],
    ?line lists:foreach(SFun(M1s), perms(M1L)),
    M2L = [{1,a},{2,b},{2,b}],
    M2s = [{1,a},{2,b}],
    ?line lists:foreach(SFun(M2s), perms(M2L)),
    M3 = [{1,a},{2,b},{3,c}],
    ?line lists:foreach(SFun(M3), perms(M3)),

    ok.

ukeysort_stable(doc) ->   ["ukeysort should keep the first duplicate"];
ukeysort_stable(suite) -> [];
ukeysort_stable(Config) when is_list(Config) ->
    ?line ok = ukeysort_check(1, [{1,b},{1,c}], [{1,b}]),
    ?line ok = ukeysort_check(1, [{1,c},{1,b}], [{1,c}]),
    ?line ok = ukeysort_check(1,
                              [{1,c},{1,b},{2,x},{3,p},{2,a}],
                              [{1,c},{2,x},{3,p}]),

    ?line ok = ukeysort_check(1, [{1,a},{1,b},{1,b}], [{1,a}]),
    ?line ok = ukeysort_check(1, [{2,a},{1,b},{2,a}], [{1,b},{2,a}]),

    ?line ok = ukeysort_check_stability(bigfunlist(3)),
    ?line ok = ukeysort_check_stability(bigfunlist(10)),
    ?line ok = ukeysort_check_stability(bigfunlist(100)),
    ?line ok = ukeysort_check_stability(bigfunlist(1000)),
    ?line case erlang:system_info(modified_timing_level) of
              undefined -> ok = ukeysort_check_stability(bigfunlist(10000));
              _ -> ok
          end,
    ok.

ukeysort_error(doc) ->   ["ukeysort should exit when given bad arguments"];
ukeysort_error(suite) -> [];
ukeysort_error(Config) when is_list(Config) ->
    ?line {'EXIT', _} = (catch lists:ukeysort(0, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:ukeysort(3, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:ukeysort(1.5, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:ukeysort(x, [{1,b},{1,c}])),
    ?line {'EXIT', _} = (catch lists:ukeysort(x, [])),
    ?line {'EXIT', _} = (catch lists:ukeysort(x, [{1,b}])),
    ?line {'EXIT', _} = (catch lists:ukeysort(1, [a,b])),
    ?line {'EXIT', _} = (catch lists:ukeysort(1, [{1,b} | {1,c}])),
    ok.

ukeysort_i(doc) ->   ["ukeysort with other key than first element"];
ukeysort_i(suite) -> [];
ukeysort_i(Config) when is_list(Config) ->
    ?line ok = ukeysort_check(2, [{a,2},{b,1},{c,3}], [{b,1},{a,2},{c,3}]),
    ok.

ukeysort_rand(doc) ->   ["ukeysort on big randomized lists"];
ukeysort_rand(suite) -> [];
ukeysort_rand(Config) when is_list(Config) ->
    ?line ok = ukeysort_check3(2, biglist(10)),
    ?line ok = ukeysort_check3(2, biglist(100)),
    ?line ok = ukeysort_check3(2, biglist(1000)),
    ?line ok = ukeysort_check3(2, biglist(10000)),

    ?line ok = gen_ukeysort_check(1, ubiglist(10)),
    ?line ok = gen_ukeysort_check(1, ubiglist(100)),
    ?line ok = gen_ukeysort_check(1, ubiglist(1000)),
    ?line ok = gen_ukeysort_check(1, ubiglist(10000)),
    ok.

%% Check that ukeysort/2 is stable and correct relative keysort/2.
%% (this is not affected by the fact that keysort/2 is no longer really 
%%  stable; ucheck_stability/1 checks ukeysort/2 (and usort/1, of course))
gen_ukeysort_check(I, Input) ->
    U = lists:ukeysort(I, Input),
    S = lists:keysort(I, Input),
    case U == no_dups_keys(S, I) of
	true ->
	    ok;
	false ->
	    io:format("~w~n", [Input]),
	    erlang:error(gen_ukeysort_check)
    end.

%% Used for checking that the first copy is kept.
ukeysort_check_stability(L) ->
    I = 1,
    U = lists:ukeysort(I, L),
    S = no_dups_keys(lkeysort(I, L), I),
    check_stab(L, U, S, "ukeysort/2", "usort/2").

%%% Uniquely keysort a list, check that the returned list is what we
%%% expected, and that it is actually sorted.
ukeysort_check(I, Input, Expected) ->
    ?line Expected = lists:ukeysort(I, Input),
    ucheck_sorted(I, Input, Expected).

ukeysort_check3(I, Input) ->
    ucheck_sorted(I, 3, Input, lists:ukeysort(I, Input)).

ucheck_sorted(I, Input, L) ->
    ucheck_sorted(I, I, Input, L).

%%% Check that a list is ukeysorted by element I. Elements comparing
%%% equal should be sorted according to element J.
ucheck_sorted(_I, _J, _Input, []) ->
    ok;
ucheck_sorted(I, J, Input, [A | Rest]) ->
    case catch ucheck_sorted1(I, J, A, Rest) of
	{'EXIT', _} ->
	    io:format("~w~n", [Input]),
	    erlang:error(ucheck_sorted);
	Reply ->
	    Reply
    end.

ucheck_sorted1(_I, _J, _A, []) ->
    ok;
ucheck_sorted1(I, J, A, [B | Rest]) ->
    ok = ukeycompare(I, J, A, B),
    ucheck_sorted1(I, J, B, Rest).

ukeycompare(I, _J, A, B) when element(I, A) < element(I, B) ->
    ok;
ukeycompare(I, J, A, B) when A =/= B,
			     element(I, A) == element(I, B), 
			     element(J, A) =< element(J, B) ->
    ok.



funmerge(doc) -> ["Merge two lists using a fun."];
funmerge(suite) -> [];
funmerge(Config) when is_list(Config) ->

    Two = [1,2],
    Six = [1,2,3,4,5,6],
    F = fun(X, Y) -> X =< Y end,

    %% 2-way merge
    ?line [] = lists:merge(F, [], []),
    ?line Two = lists:merge(F, Two, []),
    ?line Two = lists:merge(F, [], Two),
    ?line Six = lists:merge(F, [1,3,5], [2,4,6]),
    ?line Six = lists:merge(F, [2,4,6], [1,3,5]),
    ?line Six = lists:merge(F, [1,2,3], [4,5,6]),
    ?line Six = lists:merge(F, [4,5,6], [1,2,3]),
    ?line Six = lists:merge(F, [1,2,5],[3,4,6]),
    ?line [1,2,3,5,7] = lists:merge(F, [1,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:merge(F, [1,3,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:merge(F, [1,3,5,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:merge(F, [2], [1,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:merge(F, [2,4], [1,3,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:merge(F, [2,4,6], [1,3,5,7]),

    F2 = fun(X,Y) -> element(1,X) =< element(1,Y) end,
    ?line [{b,2},{c,11},{c,12},{c,21},{c,22},{e,5}] =
	lists:merge(F2,[{c,11},{c,12},{e,5}], [{b,2},{c,21},{c,22}]),

    ok.

rfunmerge(doc) -> ["Reverse merge two lists using a fun."];
rfunmerge(suite) -> [];
rfunmerge(Config) when is_list(Config) ->

    Two = [2,1],
    Six = [6,5,4,3,2,1],
    F = fun(X, Y) -> X =< Y end,

    %% 2-way reversed merge
    ?line [] = lists:rmerge(F, [], []),
    ?line Two = lists:rmerge(F, Two, []),
    ?line Two = lists:rmerge(F, [], Two),
    ?line Six = lists:rmerge(F, [5,3,1], [6,4,2]),
    ?line Six = lists:rmerge(F, [6,4,2], [5,3,1]),
    ?line Six = lists:rmerge(F, [3,2,1], [6,5,4]),
    ?line Six = lists:rmerge(F, [6,5,4], [3,2,1]),
    ?line Six = lists:rmerge(F, [4,3,2],[6,5,1]),
    ?line [7,6,5,3,1] = lists:rmerge(F, [7,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rmerge(F, [7,5,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rmerge(F, [7,5,3,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rmerge(F, [2], [7,5,3,1]),
    ?line [7,5,4,3,2,1] = lists:rmerge(F, [4,2], [7,5,3,1]),
    ?line [7,6,5,4,3,2,1] = lists:rmerge(F, [6,4,2], [7,5,3,1]),

    F2 = fun(X,Y) -> element(1,X) =< element(1,Y) end,
    L1 = [{c,11},{c,12},{e,5}],
    L2 = [{b,2},{c,21},{c,22}],
    ?line true = 
	lists:merge(F2, L1, L2) == 
	lists:reverse(lists:rmerge(F2,lists:reverse(L1), lists:reverse(L2))),

    ok.


funsort_1(doc) ->   ["sort/2"];
funsort_1(suite) -> [];
funsort_1(Config) when is_list(Config) ->
    ?line ok = funsort_check(1, [], []),
    ?line ok = funsort_check(1, [{a,b}], [{a,b}]),
    ?line ok = funsort_check(1, [{a,b},{a,b}], [{a,b},{a,b}]),
    ?line ok = funsort_check(1, [{a,b},{b,c}], [{a,b},{b,c}]),
    ?line ok = funsort_check(1, [{b,c},{a,b}], [{a,b},{b,c}]),
    ?line ok = funsort_check(1,
			     [{1,e},{3,f},{2,y},{0,z},{x,14}],
			     [{0,z},{1,e},{2,y},{3,f},{x,14}]),
    F = funsort_fun(1),

    ?line [{b,1},{c,1}] = lists:sort(F, [{c,1},{b,1}]),
    ?line [{a,0},{b,2},{c,3},{d,4}] = 
	  lists:sort(F, [{d,4},{c,3},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{b,2},{c,1}] =
	  lists:sort(F, [{c,1},{b,1},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{b,2},{c,1},{d,4}] =
	  lists:sort(F, [{c,1},{b,1},{b,2},{a,0},{d,4}]),

    SFun = fun(L) -> fun(X) -> funsort_check(1, X, L) end end,
    L1 = [{1,a},{1,a},{2,b},{2,b},{3,c},{4,d},{5,e},{6,f}],
    ?line lists:foreach(SFun(L1), perms(L1)),

    ok.

funsort_stable(doc) ->   ["sort/2 should be stable"];
funsort_stable(suite) -> [];
funsort_stable(Config) when is_list(Config) ->
    ?line ok = funsort_check(1, [{1,b},{1,c}], [{1,b},{1,c}]),
    ?line ok = funsort_check(1, [{1,c},{1,b}], [{1,c},{1,b}]),
    ?line ok = funsort_check(1,
			     [{1,c},{1,b},{2,x},{3,p},{2,a}],
			     [{1,c},{1,b},{2,x},{2,a},{3,p}]),
    ok.

funsort_error(doc) ->   ["sort/2 should exit when given bad arguments"];
funsort_error(suite) -> [];
funsort_error(Config) when is_list(Config) ->
    ?line {'EXIT', _} = (catch lists:sort(1, [{1,b} , {1,c}])),
    ?line {'EXIT', _} = (catch lists:sort(fun(X,Y) -> X =< Y end, 
					  [{1,b} | {1,c}])),
    ok.

funsort_rand(doc) ->   ["sort/2 on big randomized lists"];
funsort_rand(suite) -> [];
funsort_rand(Config) when is_list(Config) ->
    ?line ok = funsort_check3(1, biglist(10)),
    ?line ok = funsort_check3(1, biglist(100)),
    ?line ok = funsort_check3(1, biglist(1000)),
    ?line ok = funsort_check3(1, biglist(10000)),
    ok.

% Do a keysort
funsort(I, L) ->
    lists:sort(funsort_fun(I), L).

funsort_check3(I, Input) ->
    check_sorted(I, 3, Input, funsort(I, Input)).

%%% Keysort a list, check that the returned list is what we expected,
%%% and that it is actually sorted.
funsort_check(I, Input, Expected) ->
    ?line Expected = funsort(I, Input),
    check_sorted(I, Input, Expected).


ufunmerge(suite) -> [];
ufunmerge(doc) -> ["Merge two lists while removing duplicates using a fun."];
ufunmerge(Conf) when is_list(Conf) ->

    Two = [1,2],
    Six = [1,2,3,4,5,6],
    F = fun(X, Y) -> X =< Y end,

    %% 2-way unique merge
    ?line [] = lists:umerge(F, [], []),
    ?line Two = lists:umerge(F, Two, []),
    ?line Two = lists:umerge(F, [], Two),
    ?line Six = lists:umerge(F, [1,3,5], [2,4,6]),
    ?line Six = lists:umerge(F, [2,4,6], [1,3,5]),
    ?line Six = lists:umerge(F, [1,2,3], [4,5,6]),
    ?line Six = lists:umerge(F, [4,5,6], [1,2,3]),
    ?line Six = lists:umerge(F, [1,2,5],[3,4,6]),
    ?line [1,2,3,5,7] = lists:umerge(F, [1,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:umerge(F, [1,3,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:umerge(F, [1,3,5,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:umerge(F, [2], [1,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:umerge(F, [2,4], [1,3,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:umerge(F, [2,4,6], [1,3,5,7]),

    ?line [1,2,3,5,7] = lists:umerge(F, [1,2,3,5,7], [2]),
    ?line [1,2,3,4,5,7] = lists:umerge(F, [1,2,3,4,5,7], [2,4]),
    ?line [1,2,3,4,5,6,7] = lists:umerge(F, [1,3,5,6,7], [2,4,6]),
    ?line [1,2,3,5,7] = lists:umerge(F, [2], [1,2,3,5,7]),
    ?line [1,2,3,4,5,7] = lists:umerge(F, [2,4], [1,2,3,4,5,7]),
    ?line [1,2,3,4,5,6,7] = lists:umerge(F, [2,4,6], [1,2,3,4,5,6,7]),

    L1 = [{a,1},{a,3},{a,5},{a,7}],
    L2 = [{b,1},{b,3},{b,5},{b,7}],
    F2 = fun(X,Y) -> element(2,X) =< element(2,Y) end,
    ?line L1 = lists:umerge(F2, L1, L2),
    ?line [{b,2},{e,5},{c,11},{c,12},{c,21},{c,22}] =
	lists:umerge(F2, [{e,5},{c,11},{c,12}], [{b,2},{c,21},{c,22}]),

    ok.

rufunmerge(suite) -> [];
rufunmerge(doc) -> 
    ["Reverse merge two lists while removing duplicates using a fun."];
rufunmerge(Conf) when is_list(Conf) ->
    Two = [2,1],
    Six = [6,5,4,3,2,1],
    F = fun(X, Y) -> X =< Y end,

    %% 2-way reversed unique merge
    ?line [] = lists:rumerge(F, [], []),
    ?line Two = lists:rumerge(F, Two, []),
    ?line Two = lists:rumerge(F, [], Two),
    ?line Six = lists:rumerge(F, [5,3,1], [6,4,2]),
    ?line Six = lists:rumerge(F, [6,4,2], [5,3,1]),
    ?line Six = lists:rumerge(F, [3,2,1], [6,5,4]),
    ?line Six = lists:rumerge(F, [6,5,4], [3,2,1]),
    ?line Six = lists:rumerge(F, [4,3,2],[6,5,1]),
    ?line [7,6,5,3,1] = lists:rumerge(F, [7,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rumerge(F, [7,5,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge(F, [7,5,3,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rumerge(F, [2], [7,5,3,1]),
    ?line [7,5,4,3,2,1] = lists:rumerge(F, [4,2], [7,5,3,1]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge(F, [6,4,2], [7,5,3,1]),

    ?line [7,6,5,3,1] = lists:rumerge(F, [7,6,5,3,1], [6]),
    ?line [7,6,5,4,3,1] = lists:rumerge(F, [7,6,5,4,3,1], [6,4]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge(F, [7,6,5,4,3,2,1], [6,4,2]),
    ?line [7,5,3,2,1] = lists:rumerge(F, [2], [7,5,3,2,1]),
    ?line [7,5,4,3,2,1] = lists:rumerge(F, [4,2], [7,5,4,3,2,1]),
    ?line [7,6,5,4,3,2,1] = lists:rumerge(F, [6,4,2], [7,6,5,4,3,2,1]),

    F2 = fun(X,Y) -> element(1,X) =< element(1,Y) end,
    L1 = [{1,a},{1,b},{1,a}],
    L2 = [{1,a},{1,b},{1,a}],
    ?line true = lists:umerge(F2, L1, L2) == 
	lists:reverse(lists:rumerge(F, lists:reverse(L2), lists:reverse(L1))),

    L3 = [{c,11},{c,12},{e,5}],
    L4 = [{b,2},{c,21},{c,22}],
    ?line true = 
	lists:umerge(F2, L3, L4) == 
	lists:reverse(lists:rumerge(F2,lists:reverse(L3), lists:reverse(L4))),

    ok.

ufunsort_1(doc) ->   ["usort/2"];
ufunsort_1(suite) -> [];
ufunsort_1(Config) when is_list(Config) ->
    ?line ok = ufunsort_check(1, [], []),
    ?line ok = ufunsort_check(1, [{a,b}], [{a,b}]),
    ?line ok = ufunsort_check(1, [{a,b},{a,b}], [{a,b}]),
    ?line ok = ufunsort_check(1, [{a,b},{b,c}], [{a,b},{b,c}]),
    ?line ok = ufunsort_check(1, [{b,c},{a,b}], [{a,b},{b,c}]),
    ?line ok = ufunsort_check(1,
			      [{1,e},{3,f},{2,y},{0,z},{x,14}],
			      [{0,z},{1,e},{2,y},{3,f},{x,14}]),
    ?line ok = ufunsort_check(1,
			      [{1,a},{2,b},{3,c},{2,b},{1,a},{2,b},{3,c},
			       {2,b},{1,a}],
			      [{1,a},{2,b},{3,c}]),
    ?line ok = ufunsort_check(1, 
			      [{1,a},{1,a},{1,b},{1,b},{1,a},{2,a}],
			      [{1,a},{2,a}]),

    F = funsort_fun(1),
    L1 = [{1,a},{1,b},{1,a}],
    L2 = [{1,a},{1,b},{1,a}],
    ?line ok = ufunsort_check(1, lists:keymerge(1, L1, L2), 
                              lists:umerge(F, lists:usort(F, L1), 
                                           lists:usort(F, L2))),
    L3 = [{1,a},{1,b},{1,a},{2,a}],
    ?line ok = ufunsort_check(1, lists:keymerge(1, L3, L2), 
                              lists:umerge(F, lists:usort(F, L3), 
                                           lists:usort(F, L2))),
    L4 = [{1,b},{1,a}],
    ?line ok = ufunsort_check(1, lists:keymerge(1, L1, L4), 
                              lists:umerge(F, lists:usort(F, L1), 
                                           lists:usort(F, L4))),
    L5 = [{1,a},{1,b},{1,a},{2,a}],
    ?line ok = ufunsort_check(1, lists:keymerge(1, L5, []), 
                              lists:umerge(F, lists:usort(F, L5), [])),
    L6 = [{3,a}],
    ?line ok = ufunsort_check(1, lists:keymerge(1, L5, L6), 
                              lists:umerge(F, lists:usort(F, L5), 
                                           lists:usort(F, L6))),

    ?line [{b,1},{c,1}] = lists:usort(F, [{c,1},{c,1},{b,1}]),
    ?line [{a,0},{b,2},{c,3},{d,4}] = 
	  lists:usort(F, [{d,4},{c,3},{b,2},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{c,1}] =
	  lists:usort(F, [{c,1},{b,1},{b,1},{b,2},{b,2},{a,0}]),
    ?line [{a,0},{b,1},{c,1},{d,4}] =
	  lists:usort(F, [{c,1},{b,1},{b,2},{a,0},{a,0},{d,4},{d,4}]),

    SFun = fun(L) -> fun(X) -> ufunsort_check(1, X, L) end end,
    PL = [{1,a},{2,b},{3,c},{4,d},{5,e},{6,f}],
    Ps = perms([{1,a},{2,b},{3,c},{4,d},{5,e},{6,f},{2,b},{1,a}]),
    ?line lists:foreach(SFun(PL), Ps),

    ok.

ufunsort_stable(doc) ->   ["usort/2 should be stable"];
ufunsort_stable(suite) -> [];
ufunsort_stable(Config) when is_list(Config) ->
    ?line ok = ufunsort_check(1, [{1,b},{1,c}], [{1,b}]),
    ?line ok = ufunsort_check(1, [{1,c},{1,b}], [{1,c}]),
    ?line ok = ufunsort_check(1,
			      [{1,c},{1,b},{2,x},{3,p},{2,a}],
			      [{1,c},{2,x},{3,p}]),

    ?line ok = ufunsort_check_stability(bigfunlist(10)),
    ?line ok = ufunsort_check_stability(bigfunlist(100)),
    ?line ok = ufunsort_check_stability(bigfunlist(1000)),
    ?line case erlang:system_info(modified_timing_level) of
              undefined -> ok = ufunsort_check_stability(bigfunlist(10000));
              _ -> ok
          end,
    ok.

ufunsort_error(doc) ->   ["usort/2 should exit when given bad arguments"];
ufunsort_error(suite) -> [];
ufunsort_error(Config) when is_list(Config) ->
    ?line {'EXIT', _} = (catch lists:usort(1, [{1,b} , {1,c}])),
    ?line {'EXIT', _} = (catch lists:usort(fun(X,Y) -> X =< Y end, 
					   [{1,b} | {1,c}])),
    ok.

ufunsort_rand(doc) ->   ["usort/2 on big randomized lists"];
ufunsort_rand(suite) -> [];
ufunsort_rand(Config) when is_list(Config) ->
    ?line ok = ufunsort_check3(1, biglist(10)),
    ?line ok = ufunsort_check3(1, biglist(100)),
    ?line ok = ufunsort_check3(1, biglist(1000)),
    ?line ok = ufunsort_check3(1, biglist(10000)),

    ?line ok = gen_ufunsort_check(1, ubiglist(100)),
    ?line ok = gen_ufunsort_check(1, ubiglist(1000)),
    ?line ok = gen_ufunsort_check(1, ubiglist(10000)),
    ok.

%% Check that usort/2 is stable and correct relative sort/2.
gen_ufunsort_check(I, Input) ->
    U = ufunsort(I, Input),
    S = funsort(I, Input),
    case U == no_dups_keys(S, I) of
	true ->
	    ok;
	false ->
	    io:format("~w~n", [Input]),
	    erlang:error(gen_ufunsort_check)
    end.

%% Used for checking that the first copy is kept.
ufunsort_check_stability(L) ->
    I = 1,
    U = ufunsort(I, L),
    S = no_dups(funsort(I, L)),
    check_stab(L, U, S, "usort/2", "sort/2").

ufunsort_check3(I, Input) ->
    ucheck_sorted(I, 3, Input, ufunsort(I, Input)).

%%% Keysort a list, check that the returned list is what we expected,
%%% and that it is actually sorted.
ufunsort_check(I, Input, Expected) ->
    ?line Expected = ufunsort(I, Input),
    ucheck_sorted(I, Input, Expected).

% Do a keysort
ufunsort(I, L) ->
    lists:usort(funsort_fun(I), L).

funsort_fun(I) ->
    fun(A, B) when tuple_size(A) >= I, tuple_size(B) >= I ->
            element(I, A) =< element(I, B)
    end.

check_stab(L, U, S, US, SS) ->
    UP = explicit_pid(U),
    SP = explicit_pid(S),
    case UP == SP of
	true ->
	    ok;
	false ->
	    io:format("In: ~w~n", [explicit_pid(L)]),
	    io:format("~s: ~w~n", [US, UP]),
	    io:format("~s:  ~w~n", [SS, SP]),
	    erlang:error(unstable)
    end.

%%%------------------------------------------------------------
%%% Generate lists of given length, containing 3-tuples with
%%% random integer elements in the range 0..44 as elements 1 and 2.
%%% Element 3 in the tuple is the position of the tuple in the list.

biglist(N) ->
    rand:seed(exsplus),
    biglist(N, []).

biglist(0, L) ->
    L;
biglist(N, L) ->
    E = random_tuple(45, N),
    biglist(N-1, [E|L]).

%%%------------------------------------------------------------
%%% Generate lists of given length, containing 2-tuples with
%%% random integer elements in the range 0..10 as element 1.
%%% Element 2 in the tuple is a random integer in the range 0..5.
%%% No sequence number.

ubiglist(N) ->
    rand:seed(exsplus),
    ubiglist(N, []).

ubiglist(0, L) ->
    L;
ubiglist(N, L) ->
    E = urandom_tuple(11, 6),
    ubiglist(N-1, [E|L]).
    
urandom_tuple(N, I) ->
    R1 = randint(N),
    R2 = randint(I),
    {R1, R2}.

%%%------------------------------------------------------------
%%% Generate lists of given length, containing 2-tuples with random
%%% integer elements in the range 0..10 as elements 1. All tuples have
%%% the same function as element 2, but every function is created in a
%%% unique process. ==/2 will return 'true' for any pair of functions,
%%% but erlang:fun_info(Fun, pid) can be used for distinguishing
%%% functions created in different processes. The pid acts like a
%%% sequence number.

bigfunlist(N) ->
    rand:seed(exsplus),
    bigfunlist_1(N).

bigfunlist_1(N) when N < 30000 -> % Now (R8) max 32000 different pids.
    case catch bigfunlist(N, 0, []) of
	{'EXIT', _} ->
	    bigfunlist_1(N);
	Reply ->
	    Reply
    end.

bigfunlist(0, _P, L) ->
    lists:reverse(L);
bigfunlist(N, P, L) ->
    {E, NP} = random_funtuple(P, 11),
    bigfunlist(N-1, NP, [E | L]).
    
random_funtuple(P, N) ->
    R = randint(N),
    F = make_fun(),
    NP = fun_pid(F),
    true = NP > P,
    {{R, F}, NP}.

make_fun() ->
    Pid = spawn(?MODULE, make_fun, [self()]),
    receive {Pid, Fun} -> Fun end.
    
make_fun(Pid) ->
    Pid ! {self(), fun make_fun/1}.

fun_pid(Fun) ->
    erlang:fun_info(Fun, pid).

random_tuple(N, Seq) ->
    R1 = randint(N),
    R2 = randint(N),
    {R1, R2, Seq}.

randint(N) ->
    trunc(rand:uniform() * N).

%% The first "duplicate" is kept.
no_dups([]) ->
    [];
no_dups([H | T]) ->
    no_dups(H, T, []).

no_dups(H, [H1 | T], L) when H == H1 ->
    no_dups(H, T, L);
no_dups(H, [H1 | T], L) ->
    no_dups(H1, T, [H | L]);
no_dups(H, [], L) ->
    lists:reverse([H | L]).

%% The first "duplicate" is kept.
no_dups_keys([], _I) ->
    [];
no_dups_keys([H | T], I) ->
    no_dups_keys(H, T, [], I).

no_dups_keys(H, [H1 | T], L, I) when element(I, H) == element(I, H1) ->
    no_dups_keys(H, T, L, I);
no_dups_keys(H, [H1 | T], L, I) ->
    no_dups_keys(H1, T, [H | L], I);
no_dups_keys(H, [], L, _I) ->
    lists:reverse([H | L]).

perms([]) ->
    [[]];
perms(L) ->
    [[H|T] || H <- L, T <- perms(L--[H])].

%%%------------------------------------------------------------
%%% Test the sort routines with randomly generated lists.

-record(state, {sort = 0, usort = 0, stable = 0}).

%% Run it interactively. 'stop' or 'info' recognized commands.
sort_loop() ->
    sort_loop(5000).

sort_loop(N) when is_integer(N), N > 0 ->
    Pid = spawn_link(?MODULE, sloop, [N]),
    sort_loop_1(Pid).

sort_loop_1(Pid) ->
    case io:get_line('? ') of
	eof ->
	    ok;
	"stop\n" ->
	    Pid ! {self(), stop},
	    receive {Pid, S} -> display_state(S) end;
	"info\n" ->
	    Pid ! {self(), info},
	    receive {Pid, S} -> display_state(S) end,
	    sort_loop_1(Pid);
	_Other ->
	    sort_loop_1(Pid)
    end.

sloop(N) ->
    rand:seed(exsplus),
    sloop(N, #state{}).

sloop(N, S) ->
    receive
	{From, stop} ->
	    From ! {self(), S};
	{From, info} ->
	    From ! {self(), S},
	    sloop(N, S)
    after 0 ->
	    Len = randint(N),
	    NS = case randint(3) of
		     0 ->
			 BL = biglist(Len, []),
			 ok = check(BL),
			 ok = keysort_check3(1, BL),
			 ok = funsort_check3(1, BL),
			 S#state{sort = S#state.sort + 1};
		     1 ->
			 BL = ubiglist(Len, []),
			 ok = ucheck(BL),
			 ok = gen_ukeysort_check(1, BL),
			 ok = gen_ufunsort_check(1, BL),
			 S#state{usort = S#state.usort + 1};
		     2 ->
			 BL = bigfunlist(Len),
			 %% ok = check_stability(BL),
			 ok = ucheck_stability(BL),
			 ok = ukeysort_check_stability(BL),
			 ok = ufunsort_check_stability(BL),
			 S#state{stable = S#state.stable + 1}
		 end,
	    sloop(N, NS)
    end.
	    
display_state(S) ->    
    io:format("sort:   ~p~n", [S#state.sort]),
    io:format("usort:  ~p~n", [S#state.usort]),
    io:format("stable: ~p~n", [S#state.stable]).

%% This version of sort/1 is really stable; the order of equal
%% elements is kept. It is used for checking the current
%% implementation of usort/1 etc.

lsort([X, Y | L] = L0) when X =< Y ->
    case L of
	[] -> 
	    L0;
	[Z] when Y =< Z ->
	    L0;
	[Z] when X =< Z ->
	    [X, Z, Y];
	[Z] ->
	    [Z, X, Y];
	_ ->
	    split_1(X, Y, L, [], [])
    end;
lsort([X, Y | L]) ->
    case L of
	[] ->
	    [Y, X];
	[Z] when X =< Z ->
	    [Y, X | L];
	[Z] when Y =< Z ->
	    [Y, Z, X];
	[Z] ->
	    [Z, Y, X];
	_ ->
	    split_2(X, Y, L, [], [])
    end;
lsort([_] = L) ->
    L;
lsort([] = L) ->
    L.

split_1(X, Y, [Z | L], R, Rs) when Z >= Y ->
    split_1(Y, Z, L, [X | R], Rs);
split_1(X, Y, [Z | L], R, Rs) when Z >= X ->
    split_1(Z, Y, L, [X | R], Rs);
split_1(X, Y, [Z | L], [], Rs) ->
    split_1(X, Y, L, [Z], Rs);
split_1(X, Y, [Z | L], R, Rs) ->
    split_1_1(X, Y, L, R, Rs, Z);
split_1(X, Y, [], R, Rs) ->
    rmergel([[Y, X | R] | Rs], [], asc).

split_1_1(X, Y, [Z | L], R, Rs, S) when Z >= Y ->
    split_1_1(Y, Z, L, [X | R], Rs, S);
split_1_1(X, Y, [Z | L], R, Rs, S) when Z >= X ->
    split_1_1(Z, Y, L, [X | R], Rs, S);
split_1_1(X, Y, [Z | L], R, Rs, S) when S =< Z ->
    split_1(S, Z, L, [], [[Y, X | R] | Rs]);
split_1_1(X, Y, [Z | L], R, Rs, S) ->
    split_1(Z, S, L, [], [[Y, X | R] | Rs]);
split_1_1(X, Y, [], R, Rs, S) ->
    rmergel([[S], [Y, X | R] | Rs], [], asc).

split_2(X, Y, [Z | L], R, Rs) when Z < Y ->
    split_2(Y, Z, L, [X | R], Rs);
split_2(X, Y, [Z | L], R, Rs) when Z < X ->
    split_2(Z, Y, L, [X | R], Rs);
split_2(X, Y, [Z | L], [], Rs) ->
    split_2(X, Y, L, [Z], Rs);
split_2(X, Y, [Z | L], R, Rs) ->
    split_2_1(X, Y, L, R, Rs, Z);
split_2(X, Y, [], R, Rs) ->
    mergel([[Y, X | R] | Rs], [], desc).

split_2_1(X, Y, [Z | L], R, Rs, S) when Z < Y ->
    split_2_1(Y, Z, L, [X | R], Rs, S);
split_2_1(X, Y, [Z | L], R, Rs, S) when Z < X ->
    split_2_1(Z, Y, L, [X | R], Rs, S);
split_2_1(X, Y, [Z | L], R, Rs, S) when S > Z ->
    split_2(S, Z, L, [], [[Y, X | R] | Rs]);
split_2_1(X, Y, [Z | L], R, Rs, S) ->
    split_2(Z, S, L, [], [[Y, X | R] | Rs]);
split_2_1(X, Y, [], R, Rs, S) ->
    mergel([[S], [Y, X | R] | Rs], [], desc).

mergel([[] | L], Acc, O) ->
    mergel(L, Acc, O);
mergel([T1, [H2 | T2] | L], Acc, asc) ->
    mergel(L, [merge2_1(T1, H2, T2, []) | Acc], asc);
mergel([[H2 | T2], T1 | L], Acc, desc) ->
    mergel(L, [merge2_1(T1, H2, T2, []) | Acc], desc);
mergel([L], [], _O) ->
    L;
mergel([L], Acc, O) ->
    rmergel([lists:reverse(L, []) | Acc], [], O);
mergel([], [], _O) ->
    [];
mergel([], Acc, O) ->
    rmergel(Acc, [], O);
mergel([A, [] | L], Acc, O) ->
    mergel([A | L], Acc, O);
mergel([A, B, [] | L], Acc, O) ->
    mergel([A, B | L], Acc, O).

rmergel([[H2 | T2], T1 | L], Acc, asc) ->
    rmergel(L, [rmerge2_1(T1, H2, T2, []) | Acc], asc);
rmergel([T1, [H2 | T2] | L], Acc, desc) ->
    rmergel(L, [rmerge2_1(T1, H2, T2, []) | Acc], desc);
rmergel([L], Acc, O) ->
    mergel([lists:reverse(L, []) | Acc], [], O);
rmergel([], Acc, O) ->
    mergel(Acc, [], O).

merge2_1([H1 | T1], H2, T2, M) when H1 =< H2 ->
    merge2_1(T1, H2, T2, [H1 | M]);
merge2_1([H1 | T1], H2, T2, M) ->
    merge2_2(T1, H1, T2, [H2 | M]);
merge2_1([], H2, T2, M) ->
    lists:reverse(T2, [H2 | M]).

merge2_2(T1, H1, [H2 | T2], M) when H1 =< H2 ->
    merge2_1(T1, H2, T2, [H1 | M]);
merge2_2(T1, H1, [H2 | T2], M) ->
    merge2_2(T1, H1, T2, [H2 | M]);
merge2_2(T1, H1, [], M) ->
    lists:reverse(T1, [H1 | M]).

rmerge2_1([H1 | T1], H2, T2, M) when H1 =< H2 ->
    rmerge2_2(T1, H1, T2, [H2 | M]);
rmerge2_1([H1 | T1], H2, T2, M) ->
    rmerge2_1(T1, H2, T2, [H1 | M]);
rmerge2_1([], H2, T2, M) ->
    lists:reverse(T2, [H2 | M]).

rmerge2_2(T1, H1, [H2 | T2], M) when H1 =< H2 ->
    rmerge2_2(T1, H1, T2, [H2 | M]);
rmerge2_2(T1, H1, [H2 | T2], M) ->
    rmerge2_1(T1, H2, T2, [H1 | M]);
rmerge2_2(T1, H1, [], M) ->
    lists:reverse(T1, [H1 | M]).



%% This version of keysort/2 is really stable; the order of equal
%% elements is kept. It is used for checking the current
%% implementation of ukeysort/2 etc.

lkeysort(Index, L) when is_integer(Index), Index > 0 ->
    case L of
	[] -> L;
	[_] -> L;
	[X, Y | T] ->
	    EX = element(Index, X),
	    EY = element(Index, Y),
	    if
		EX =< EY ->
		    keysplit_1(Index, X, EX, Y, EY, T, [], []);
		true ->
		    keysplit_2(Index, Y, EY, T, [X])
	    end
    end.

keysplit_1(I, X, EX, Y, EY, [Z | L], R, Rs) ->
    EZ = element(I, Z),
    if 
	EY =< EZ ->
	    keysplit_1(I, Y, EY, Z, EZ, L, [X | R], Rs);
	EX =< EZ ->
	    keysplit_1(I, Z, EZ, Y, EY, L, [X | R], Rs);
	true, R == [] ->
	    keysplit_1(I, X, EX, Y, EY, L, [Z], Rs);
	true ->
	    keysplit_1_1(I, X, EX, Y, EY, L, R, Rs, Z, EZ)
    end;
keysplit_1(I, X, _EX, Y, _EY, [], R, Rs) ->
    rkeymergel(I, [[Y, X | R] | Rs], []).

%% One out-of-order element, S.
keysplit_1_1(I, X, EX, Y, EY, [Z | L], R, Rs, S, ES) ->
    EZ = element(I, Z),
    if
	EY =< EZ ->
	    keysplit_1_1(I, Y, EY, Z, EZ, L, [X | R], Rs, S, ES);
	EX =< EZ ->
	    keysplit_1_1(I, Z, EZ, Y, EY, L, [X | R], Rs, S, ES);
	ES =< EZ ->
	    keysplit_1(I, S, ES, Z, EZ, L, [], [[Y, X | R] | Rs]);
	true ->
	    keysplit_1(I, Z, EZ, S, ES, L, [], [[Y, X | R] | Rs])
    end;
keysplit_1_1(I, X, _EX, Y, _EY, [], R, Rs, S, _ES) ->
    rkeymergel(I, [[S], [Y, X | R] | Rs], []).

%% Descending.
keysplit_2(I, Y, EY, [Z | L], R) ->
    EZ = element(I, Z),
    if
	EY =< EZ ->
            keysplit_1(I, Y, EY, Z, EZ, L, [], [lists:reverse(R, [])]);
        true ->
            keysplit_2(I, Z, EZ, L, [Y | R])
    end;
keysplit_2(_I, Y, _EY, [], R) ->
    [Y | R].

keymergel(I, [T1, [H2 | T2] | L], Acc) ->
    keymergel(I, L, [keymerge2_1(I, T1, element(I, H2), H2, T2, []) | Acc]);
keymergel(_I, [L], []) ->
    L;
keymergel(I, [L], Acc) ->
    rkeymergel(I, [lists:reverse(L, []) | Acc], []);
keymergel(I, [], Acc) ->
    rkeymergel(I, Acc, []).

rkeymergel(I, [[H2 | T2], T1 | L], Acc) ->
    rkeymergel(I, L, [rkeymerge2_1(I, T1, element(I, H2), H2, T2, []) | Acc]);
rkeymergel(I, [L], Acc) ->
    keymergel(I, [lists:reverse(L, []) | Acc], []);
rkeymergel(I, [], Acc) ->
    keymergel(I, Acc, []).

keymerge2_1(I, [H1 | T1], E2, H2, T2, M) ->
    E1 = element(I, H1),
    if 
	E1 =< E2 ->
	    keymerge2_1(I, T1, E2, H2, T2, [H1 | M]);
	true ->
	    keymerge2_2(I, T1, E1, H1, T2, [H2 | M])
    end;
keymerge2_1(_I, [], _E2, H2, T2, M) ->
    lists:reverse(T2, [H2 | M]).

keymerge2_2(I, T1, E1, H1, [H2 | T2], M) ->
    E2 = element(I, H2),
    if
	E1 =< E2 ->
	    keymerge2_1(I, T1, E2, H2, T2, [H1 | M]);
	true ->
	    keymerge2_2(I, T1, E1, H1, T2, [H2 | M])
    end;
keymerge2_2(_I, T1, _E1, H1, [], M) ->
    lists:reverse(T1, [H1 | M]).

rkeymerge2_1(I, [H1 | T1], E2, H2, T2, M) ->
    E1 = element(I, H1),
    if
	E1 =< E2 ->
	    rkeymerge2_2(I, T1, E1, T2, [H2 | M], H1);
	true ->
	    rkeymerge2_1(I, T1, E2, H2, T2, [H1 | M])
    end;
rkeymerge2_1(_I, [], _E2, H2, T2, M) ->
    lists:reverse(T2, [H2 | M]).

rkeymerge2_2(I, T1, E1, [H2 | T2], M, H1) ->
    E2 = element(I, H2),
    if
	E1 =< E2 ->
	    rkeymerge2_2(I, T1, E1, T2, [H2 | M], H1);
	true ->
	    rkeymerge2_1(I, T1, E2, H2, T2, [H1 | M])
    end;
rkeymerge2_2(_I, T1, _E1, [], M, H1) ->
    lists:reverse(T1, [H1 | M]).


%%%------------------------------------------------------------


seq_loop(doc) ->
    ["Test for infinite loop (OTP-2404)."];
seq_loop(suite) ->
    [];
seq_loop(Config) when is_list(Config) ->
    ?line _ = (catch lists:seq(1, 5, -1)),
    ok.

seq_2(doc) ->
    ["Non-error cases for seq/2"];
seq_2(suite) ->
    [];
seq_2(Config) when is_list(Config) ->
    ?line [1,2,3] = lists:seq(1,3),
    ?line [1] = lists:seq(1,1),
    ?line Big = 748274827583793785928592859,
    ?line Big1 = Big+1,
    ?line Big2 = Big+2,
    ?line [Big, Big1, Big2] = lists:seq(Big, Big+2),
    ok.

seq_2_e(doc) ->
    ["Error cases for seq/2"];
seq_2_e(suite) ->
    [];
seq_2_e(Config) when is_list(Config) ->
    ?line seq_error([4, 2]),
    ?line seq_error([1, a]),
    ?line seq_error([1.0, 2.0]),
    ok.

seq_error(Args) ->
    {'EXIT', _} = (catch apply(lists, seq, Args)).

seq_3(doc) ->
    ["Non-error cases for seq/3"];
seq_3(suite) ->
    [];
seq_3(Config) when is_list(Config) ->
    ?line [1,2,3] = lists:seq(1,3,1),
    ?line [1] = lists:seq(1,1,1),
    ?line Big = 748274827583793785928592859,
    ?line Big1 = Big+1,
    ?line Big2 = Big+2,
    ?line [Big, Big1, Big2] = lists:seq(Big, Big+2,1),

    ?line [3,2,1] = lists:seq(3,1,-1),
    ?line [1] = lists:seq(1,1,-1),

    ?line [3,1] = lists:seq(3,1,-2),
    ?line [1] = lists:seq(1, 10, 10),
    ?line [1, 4, 7, 10, 13, 16, 19] = lists:seq(1, 19, 3),
    ?line [1, 4, 7, 10, 13, 16, 19] = lists:seq(1, 20, 3),
    ?line [1, 4, 7, 10, 13, 16, 19] = lists:seq(1, 21, 3),

    ?line [1] = lists:seq(1, 1, 0),		%OTP-2613
    ok.

seq_3_e(doc) ->
    ["Error cases for seq/3"];
seq_3_e(suite) ->
    [];
seq_3_e(Config) when is_list(Config) ->
    ?line seq_error([4, 2, 1]),
    ?line seq_error([3, 5, -1]),
    ?line seq_error([1, a, 1]),
    ?line seq_error([1.0, 2.0, 1]),

    ?line seq_error([1, 3, 1.0]),
    ?line seq_error([1, 3, a]),
    ?line seq_error([1, 3, 0]),

    ?line seq_error([a, a, 0]),
    ok.

otp_7230(doc) -> 
    ["OTP-7230. seq/1,2 returns the empty list"];
otp_7230(suite) ->
    [];
otp_7230(Config) when is_list(Config) ->
    From = -10,
    To = 10,
    StepFrom = -10,
    StepTo = 10,

    L = lists:seq(From, To),
    SL = lists:seq(StepFrom, StepTo),
    ?line [] = 
    [{F, T, S} || 
        F <- L, T <- L, S <- SL,
          not check_seq(F, T, S, catch lists:seq(F, T, S))
        orelse
          S =:= 1 andalso not check_seq(F, T, S, catch lists:seq(F, T))
        ].

check_seq(From, To, 0, R) ->
      From =:= To andalso R =:= [From]
    orelse
      From =/= To andalso is_tuple(R) andalso element(1, R) =:= 'EXIT';
check_seq(From, To, Step, []) when Step =/= 0 ->
      0 =:= property(From, To, Step)
    andalso 
    (
      Step > 0 andalso To < From andalso From-To =< Step
    orelse
      Step < 0 andalso To > From andalso To-From =< -Step
    );
check_seq(From, To, Step, R) when R =/= [], To < From, Step > 0 ->
    is_tuple(R) andalso element(1, R) =:= 'EXIT';
check_seq(From, To, Step, R) when R =/= [], To > From, Step < 0 ->
    is_tuple(R) andalso element(1, R) =:= 'EXIT';
check_seq(From, To, Step, L) when is_list(L), L =/= [], Step =/= 0 ->
    First = hd(L),
    Last = lists:last(L),
    Min = lists:min(L),
    Max = lists:max(L),

      [] =:= [E || E <- L, not is_integer(E)]
    andalso
      %% The difference between two consecutive elements is Step:
      begin
        LS = [First-Step]++L,
        LR = L++[Last+Step],
        [Step] =:= lists:usort([B-A || {A,B} <- lists:zip(LS, LR)])
      end
    andalso
      %% The first element of L is From:
      From =:= First
    andalso
      %% No element outside the given interval:
      Min >= lists:min([From, To])
    andalso
      Max =< lists:max([From, To])
    andalso
      %% All elements are present:
      abs(To-Last) < abs(Step)
    andalso
      length(L) =:= property(From, To, Step);
check_seq(_From, _To, _Step, _R) ->
    false.

property(From, To, Step) ->
    ((To-From+Step) div Step).

%%%------------------------------------------------------------


-define(sublist_error2(X,Y), ?line {'EXIT', _} = (catch lists:sublist(X,Y))).
-define(sublist_error3(X,Y,Z), ?line {'EXIT', _} = (catch lists:sublist(X,Y,Z))).

sublist_2(doc) ->   ["sublist/2"];
sublist_2(suite) -> [];
sublist_2(Config) when is_list(Config) ->
    ?line [] = lists:sublist([], 0),
    ?line [] = lists:sublist([], 1),
    ?line [] = lists:sublist([a], 0),
    ?line [a] = lists:sublist([a], 1),
    ?line [a] = lists:sublist([a], 2),
    ?line [a] = lists:sublist([a|b], 1),

    ?line [a,b] = lists:sublist([a,b|c], 2),

    ok.

sublist_2_e(doc) ->   ["sublist/2 error cases"];
sublist_2_e(suite) -> [];
sublist_2_e(Config) when is_list(Config) ->
    ?sublist_error2([], -1),
    ?sublist_error2(a, -1),
    ?sublist_error2(a, 0),
    ?sublist_error2([a|b], 2),
    ?sublist_error2([a], x),
    ?sublist_error2([a], 1.5),
    ?sublist_error2([], x),
    ?sublist_error2([], 1.5),
    ok.

sublist_3(doc) ->   ["sublist/3"];
sublist_3(suite) -> [];
sublist_3(Config) when is_list(Config) ->
    ?line [] = lists:sublist([], 1, 0),
    ?line [] = lists:sublist([], 1, 1),
    ?line [] = lists:sublist([a], 1, 0),
    ?line [a] = lists:sublist([a], 1, 1),
    ?line [a] = lists:sublist([a], 1, 2),
    ?line [a] = lists:sublist([a|b], 1, 1),

    ?line [] = lists:sublist([], 1, 0),
    ?line [] = lists:sublist([], 1, 1),
    ?line [] = lists:sublist([a], 1, 0),
    ?line [a] = lists:sublist([a], 1, 1),
    ?line [a] = lists:sublist([a], 1, 2),
    ?line [] = lists:sublist([a], 2, 1),
    ?line [] = lists:sublist([a], 2, 2),
    ?line [] = lists:sublist([a], 2, 79),
    ?line [] = lists:sublist([a,b|c], 1, 0),
    ?line [] = lists:sublist([a,b|c], 2, 0),
    ?line [a] = lists:sublist([a,b|c], 1, 1),
    ?line [b] = lists:sublist([a,b|c], 2, 1),
    ?line [a,b] = lists:sublist([a,b|c], 1, 2),

    ?line [] = lists:sublist([a], 2, 0),

    ok.

sublist_3_e(doc) ->   ["sublist/3 error cases"];
sublist_3_e(suite) -> [];
sublist_3_e(Config) when is_list(Config) ->
    ?sublist_error3([], 1, -1),
    ?sublist_error3(a, 1, -1),
    ?sublist_error3(a, 1, 0),
    ?sublist_error3([a|b], 1, 2),
    ?sublist_error3([a], 1, x),
    ?sublist_error3([a], 1, 1.5),
    ?sublist_error3([], 1, x),
    ?sublist_error3([], 1, 1.5),

    ?sublist_error3([], -1, 0),
    ?sublist_error3(a, x, -1),
    ?sublist_error3([a,b], 0.5, 1),
    ?sublist_error3([a,b], 1.5, 1),
    ?sublist_error3([a], 1, x),
    ?sublist_error3([a], 1, 1.5),
    ?sublist_error3([], 1, x),
    ?sublist_error3([], 1, 1.5),

    ?sublist_error3([a], 0, -1),
    ?sublist_error3([a], 1, -1),
    ?sublist_error3([a], 2, -1),
    ?sublist_error3([a], 0, 0),
    ?sublist_error3([a], 0, 1),

    ?sublist_error3([a,b|c], 2, 2),
    ?sublist_error3([a,b|c], 3, 0),
    ?sublist_error3([a,b|c], 3, 1),
    ok.

%%%------------------------------------------------------------


-define(flatten_error1(X), ?line {'EXIT', _} = (catch lists:flatten(X))).
-define(flatten_error2(X,Y), ?line {'EXIT', _} = (catch lists:flatten(X,Y))).

%% Test lists:flatten/1,2 and lists:flatlength/1.
flatten_1(Config) when is_list(Config) ->
    [] = lists_flatten([]),
    [1,2] = lists_flatten([1,2]),
    [1,2] = lists_flatten([1,[2]]),
    [1,2] = lists_flatten([[1],2]),
    [1,2] = lists_flatten([[1],[2]]),
    [1,2] = lists_flatten([[1,2]]),
    [a,b,c,d] = lists_flatten([[a],[b,c,[d]]]),

    ok.

lists_flatten(List) ->
    Flat = lists:flatten(List),
    Flat = lists:flatten(List, []),
    Len = lists:flatlength(List),
    Len = length(Flat),
    Flat.

flatten_1_e(doc) ->   ["flatten/1 error cases"];
flatten_1_e(suite) -> [];
flatten_1_e(Config) when is_list(Config) ->
    ?flatten_error1(a),
    ?flatten_error1([a|b]),
    ?flatten_error1([[a],[b|c],[d]]),
    ok.

%%% [arndt] What if second arg isn't a proper list? This issue isn't
%%% clear-cut. Right now, I think that any term should be allowed.
%%% But I also wish this function didn't exist at all.

%% Test lists:flatten/2.
flatten_2(Config) when is_list(Config) ->
    [] = lists:flatten([], []),
    [a] = lists:flatten([a], []),
    [a,b,c,[no,flatten]] = lists:flatten([[a,[b,c]]], [[no,flatten]]),
    ok.

flatten_2_e(doc) ->   ["flatten/2 error cases"];
flatten_2_e(suite) -> [];
flatten_2_e(Config) when is_list(Config) ->
    ok.

%% Test lists:zip/2, lists:unzip/1.
zip_unzip(Config) when is_list(Config) ->
    ?line [] = lists:zip([], []),
    ?line [{a,b}] = lists:zip([a], [b]),
    ?line [{42.0,{kalle,nisse}},{a,b}] = lists:zip([42.0,a], [{kalle,nisse},b]),

    %% Longer lists.
    ?line SeqA = lists:seq(45, 200),
    ?line SeqB = [A*A || A <- SeqA],
    ?line AB = lists:zip(SeqA, SeqB),
    ?line SeqA = [A || {A,_} <- AB],
    ?line SeqB = [B || {_,B} <- AB],
    ?line {SeqA,SeqB} = lists:unzip(AB),
    
    %% Some more unzip/1.
    ?line {[],[]} = lists:unzip([]),
    ?line {[a],[b]} = lists:unzip([{a,b}]),
    ?line {[a,c],[b,d]} = lists:unzip([{a,b},{c,d}]),

    %% Error cases.
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip([], [b])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip([a], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip([a], [b,c])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip([a], [b,c])),
    ok.

%% Test lists:zip3/3, lists:unzip3/1.
zip_unzip3(Config) when is_list(Config) ->
    ?line [] = lists:zip3([], [], []),
    ?line [{a,b,c}] = lists:zip3([a], [b], [c]),

    %% Longer lists.
    ?line SeqA = lists:seq(45, 200),
    ?line SeqB = [2*A || A <- SeqA],
    ?line SeqC = [A*A || A <- SeqA],
    ?line ABC = lists:zip3(SeqA, SeqB, SeqC),
    ?line SeqA = [A || {A,_,_} <- ABC],
    ?line SeqB = [B || {_,B,_} <- ABC],
    ?line SeqC = [C || {_,_,C} <- ABC],
    ?line {SeqA,SeqB,SeqC} = lists:unzip3(ABC),

    %% Some more unzip3/1.
    ?line {[],[],[]} = lists:unzip3([]),
    ?line {[a],[b],[c]} = lists:unzip3([{a,b,c}]),

    %% Error cases.
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip3([], [], [c])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip3([], [b], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zip3([a], [], [])),

    ok.

%% Test lists:zipwith/3.
zipwith(Config) when is_list(Config) ->
    Zip = fun(A, B) -> [A|B] end,

    ?line [] = lists:zipwith(Zip, [], []),
    ?line [[a|b]] = lists:zipwith(Zip, [a], [b]),

    %% Longer lists.
    ?line SeqA = lists:seq(77, 300),
    ?line SeqB = [A*A || A <- SeqA],
    ?line AB = lists:zipwith(Zip, SeqA, SeqB),
    ?line SeqA = [A || [A|_] <- AB],
    ?line SeqB = [B || [_|B] <- AB],
    
    %% Error cases.
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith(badfun, [], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith(Zip, [], [b])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith(Zip, [a], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith(Zip, [a], [b,c])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith(Zip, [a], [b,c])),
    ok.

%% Test lists:zipwith3/4.
zipwith3(Config) when is_list(Config) ->
    Zip = fun(A, B, C) -> [A,B,C] end,

    ?line [] = lists:zipwith3(Zip, [], [], []),
    ?line [[a,b,c]] = lists:zipwith3(Zip, [a], [b], [c]),

    %% Longer lists.
    ?line SeqA = lists:seq(45, 200),
    ?line SeqB = [2*A || A <- SeqA],
    ?line SeqC = [A*A || A <- SeqA],
    ?line ABC = lists:zipwith3(Zip, SeqA, SeqB, SeqC),
    ?line SeqA = [A || [A,_,_] <- ABC],
    ?line SeqB = [B || [_,B,_] <- ABC],
    ?line SeqC = [C || [_,_,C] <- ABC],

    %% Error cases.
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith3(badfun, [], [], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith3(Zip, [], [], [c])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith3(Zip, [], [b], [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:zipwith3(Zip, [a], [], [])),

    ok.

%% Test lists:filter/2, lists:partition/2.
filter_partition(Config) when is_list(Config) ->
    F = fun(I) -> I rem 2 =:= 0 end,
    ?line filpart(F, [], []),
    ?line filpart(F, [1], []),
    ?line filpart(F, [1,3,17], []),
    ?line filpart(F, [1,2,3,17], [2]),
    ?line filpart(F, [6,8,1,2,3,17], [6,8,2]),
    ?line filpart(F, [6,8,1,2,42,3,17], [6,8,2,42]),

    %% Error cases.
    ?line {'EXIT',{function_clause,_}} = (catch lists:filter(badfun, [])),
    ?line {'EXIT',{function_clause,_}} = (catch lists:partition(badfun, [])),
    ok.

filpart(F, All, Exp) ->
    Exp = lists:filter(F, All),
    Other = lists:filter(fun(E) -> not F(E) end, All),
    {Exp,Other} = lists:partition(F, All).


otp_5939(doc) ->   ["OTP-5939. Guard tests added."];
otp_5939(suite) -> [];
otp_5939(Config) when is_list(Config) ->
    Fun1 = fun(A) -> A end,
    Fun2 = fun(A, B) -> {A,B} end,
    Fun3 = fun(A, B, C) -> {A,B,C} end,
    Pred = fun(_A) -> true end,
    Fold = fun(_E, A) -> A end,
    MapFold = fun(E, A) -> {E,A} end,

    ?line {'EXIT', _} = (catch lists:usort( [asd], [qwe])),

    ?line {'EXIT', _} = (catch lists:zipwith(func, [], [])),
    ?line [] = lists:zipwith(Fun2, [], []),
    ?line {'EXIT', _} = (catch lists:zipwith3(func, [], [], [])),
    ?line [] = lists:zipwith3(Fun3, [], [], []),
    ?line {'EXIT', _} = (catch lists:keymap(func, 1, [])),
    ?line {'EXIT', _} = (catch lists:keymap(Fun1, 0, [])),
    ?line [] = lists:keymap(Fun1, 1, []),
    ?line {'EXIT', _} = (catch lists:merge(func, [], [1])),
    ?line {'EXIT', _} = (catch lists:merge(func, [1], [])),
    ?line [] = lists:merge(Fun2, [], []),
    ?line {'EXIT', _} = (catch lists:rmerge(func, [], [1])),
    ?line {'EXIT', _} = (catch lists:rmerge(func, [1], [])),
    ?line [] = lists:rmerge(Fun2, [], []),
    ?line {'EXIT', _} = (catch lists:usort(func, [])),
    ?line {'EXIT', _} = (catch lists:usort(func, [a])),
    ?line {'EXIT', _} = (catch lists:usort(func, [a, b])),
    ?line [] = lists:usort(Fun2, []),
    ?line {'EXIT', _} = (catch lists:umerge(func, [], [1])),
    ?line {'EXIT', _} = (catch lists:merge(func, [1], [])),
    ?line [] = lists:umerge(Fun2, [], []),
    ?line {'EXIT', _} = (catch lists:rumerge(func, [], [1])),
    ?line {'EXIT', _} = (catch lists:rumerge(func, [1], [])),
    ?line [] = lists:rumerge(Fun2, [], []),
    ?line {'EXIT', _} = (catch lists:all(func, [])),
    ?line true = lists:all(Pred, []),
    ?line {'EXIT', _} = (catch lists:any(func, [])),
    ?line false = lists:any(Pred, []),
    ?line {'EXIT', _} = (catch lists:map(func, [])),
    ?line [] = lists:map(Fun1, []),
    ?line {'EXIT', _} = (catch lists:flatmap(func, [])),
    ?line [] = lists:flatmap(Fun1, []),
    ?line {'EXIT', _} = (catch lists:foldl(func, [], [])),
    ?line [] = lists:foldl(Fold, [], []),
    ?line {'EXIT', _} = (catch lists:foldr(func, [], [])),
    ?line [] = lists:foldr(Fold, [], []),
    ?line {'EXIT', _} = (catch lists:filter(func, [])),
    ?line [] = lists:filter(Pred, []),
    ?line {'EXIT', _} = (catch lists:partition(func, [])),
    ?line {[],[]} = lists:partition(Pred, []),
    ?line {'EXIT', _} = (catch lists:filtermap(func, [])),
    ?line [] = lists:filtermap(Fun1, []),
    ?line {'EXIT', _} = (catch lists:foreach(func, [])),
    ?line ok = lists:foreach(Fun1, []),
    ?line {'EXIT', _} = (catch lists:mapfoldl(func, [], [])),
    ?line {[],[]} = lists:mapfoldl(MapFold, [], []),
    ?line {'EXIT', _} = (catch lists:mapfoldr(func, [], [])),
    ?line {[],[]} = lists:mapfoldr(MapFold, [], []),
    ?line {'EXIT', _} = (catch lists:takewhile(func, [])),
    ?line [] = lists:takewhile(Pred, []),
    ?line {'EXIT', _} = (catch lists:dropwhile(func, [])),
    ?line [] = lists:dropwhile(Pred, []),
    ?line {'EXIT', _} = (catch lists:splitwith(func, [])),
    ?line {[],[]} = lists:splitwith(Pred, []),

    ok.

otp_6023(doc) ->   ["OTP-6023. lists:keyreplace/4, a typecheck."];
otp_6023(suite) -> [];
otp_6023(Config) when is_list(Config) ->
    ?line {'EXIT', _} = (catch lists:keyreplace(a, 2, [{1,a}], b)),
    ?line [{2,b}] = lists:keyreplace(a, 2, [{1,a}], {2,b}),

    ok.

otp_6606(doc) ->   ["OTP-6606. sort and keysort bug"];
otp_6606(suite) -> [];
otp_6606(Config) when is_list(Config) ->
    I = 1,
    F = float(1),
    L1 = [{F,I},{F,F},{I,I},{I,F}],
    ?line L1 = lists:keysort(1, L1),
    ?line L1 = lists:sort(L1),
    L2 = [{I,I},{I,F},{F,I},{F,F}],
    ?line L2 = lists:keysort(1, L2),
    ?line L2 = lists:sort(L2),
    ok.

%% Test lists:suffix/2.
suffix(Config) when is_list(Config) ->
    ?line true = lists:suffix([], []),
    ?line true = lists:suffix([], [a]),
    ?line true = lists:suffix([], [a,b]),
    ?line true = lists:suffix([], [a,b,c]),
    ?line true = lists:suffix([a], lists:duplicate(200000, a)),
    ?line true = lists:suffix(lists:seq(1, 1024),
			      lists:seq(2, 64000) ++ lists:seq(1, 1024)),
    ?line true = lists:suffix(lists:duplicate(20000, a),
			      lists:duplicate(200000, a)),
    ?line true = lists:suffix([2.0,3.0], [1.0,2.0,3.0]),

    %% False cases.
    ?line false = lists:suffix([a], []),
    ?line false = lists:suffix([a,b,c], []),
    ?line false = lists:suffix([a,b,c], [b,c]),
    ?line false = lists:suffix([a,b,c], [a,b,c,a,b]),
    ?line false = lists:suffix(lists:duplicate(199999, a)++[b],
			       lists:duplicate(200000, a)),
    ?line false = lists:suffix([2.0,3.0], [1,2,3]),

    %% Error cases.
    ?line {'EXIT',_} = (catch lists:suffix({a,b,c}, [])),
    ?line {'EXIT',_} = (catch lists:suffix([], {a,b})),
    ?line {'EXIT',_} = (catch lists:suffix([a|b], [])),
    ?line {'EXIT',_} = (catch lists:suffix([a,b|c], [a|b])),
    ?line {'EXIT',_} = (catch lists:suffix([a|b], [a,b|c])),
    ?line {'EXIT',_} = (catch lists:suffix([a|b], [a|b])),
    
    ok.

%% Test lists:subtract/2 and the '--' operator.
subtract(Config) when is_list(Config) ->
    ?line [] = sub([], []),
    ?line [] = sub([], [a]),
    ?line [] = sub([], lists:seq(1, 1024)),
    ?line sub_non_matching([a], []),
    ?line sub_non_matching([1,2], [make_ref()]),
    ?line sub_non_matching(lists:seq(1, 1024), [make_ref(),make_ref()]),
    
    %% Matching subtracts.
    ?line [] = sub([a], [a]),
    ?line [a] = sub([a,b], [b]),
    ?line [a] = sub([a,b], [b,c]),
    ?line [a] = sub([a,b,c], [b,c]),
    ?line [a] = sub([a,b,c], [b,c]),
    ?line [d,a,a] = sub([a,b,c,d,a,a], [a,b,c]),
    ?line [d,x,a] = sub([a,b,c,d,a,x,a], [a,b,c,a]),
    ?line [1,2,3,4,5,6,7,8,9,9999,10000,20,21,22] =
	sub(lists:seq(1, 10000)++[20,21,22], lists:seq(10, 9998)),

    %% Floats/integers.
    ?line [42.0,42.0] = sub([42.0,42,42.0], [42,42,42]),
    ?line [1,2,3,4,43.0] = sub([1,2,3,4,5,42.0,43.0], [42.0,5]),

    %% Crashing subtracts.
    ?line {'EXIT',_} = (catch sub([], [a|b])),
    ?line {'EXIT',_} = (catch sub([a], [a|b])),
    ?line {'EXIT',_} = (catch sub([a|b], [])),
    ?line {'EXIT',_} = (catch sub([a|b], [])),
    ?line {'EXIT',_} = (catch sub([a|b], [a])),

    ok.

sub_non_matching(A, B) ->
    A = sub(A, B).
    
sub(A, B) ->
    Res = A -- B,
    Res = lists:subtract(A, B).

%% Test lists:droplast/1
droplast(Config) when is_list(Config) ->
    ?line [] = lists:droplast([x]),
    ?line [x] = lists:droplast([x, y]),
    ?line {'EXIT', {function_clause, _}} = (catch lists:droplast([])),
    ?line {'EXIT', {function_clause, _}} = (catch lists:droplast(x)),

    ok.

%% Briefly test the common high-order functions to ensure they
%% are covered.
hof(Config) when is_list(Config) ->
    L = [1,2,3],
    [1,4,9] = lists:map(fun(N) -> N*N end, L),
    [1,4,5,6] = lists:flatmap(fun(1) -> [1];
				 (2) -> [];
				 (3) -> [4,5,6]
			      end, L),
    [{1,[a]},{2,[b]},{3,[c]}] =
	lists:keymap(fun(A) -> [A] end, 2, [{1,a},{2,b},{3,c}]),

    [1,3] = lists:filter(fun(N) -> N rem 2 =:= 1 end, L),
    FilterMapFun = fun(1) -> true;
		      (2) -> {true,42};
		      (3) -> false
		   end,
    [1,42] = lists:filtermap(FilterMapFun, L),
    [1,42] = lists:zf(FilterMapFun, L),

    [3,2,1] = lists:foldl(fun(E, A) -> [E|A] end, [], L),
    [1,2,3] = lists:foldr(fun(E, A) -> [E|A] end, [], L),
    {[1,4,9],[3,2,1]} = lists:mapfoldl(fun(E, A) ->
					       {E*E,[E|A]}
				       end, [], L),
    {[1,4,9],[1,2,3]} = lists:mapfoldr(fun(E, A) ->
					       {E*E,[E|A]}
				       end, [], L),

    true = lists:any(fun(N) -> N =:= 2 end, L),
    false = lists:any(fun(N) -> N =:= 42 end, L),

    true = lists:all(fun(N) -> is_integer(N) end, L),
    false = lists:all(fun(N) -> N rem 2 =:= 0 end, L),

    ok.