Smoke test erl_syntax:revert/1

This tries to make bugs like 87156887b7d82a2db53f60441a4af87034cb8789 not
happen again.

The new test takes each file in the stdlib app, passes their forms through the
erl_syntax representation, reverts them and compiles them.

1 files changed, 27 insertions, 2 deletions

diff --git a/lib/syntax_tools/test/syntax_tools_SUITE.erl b/lib/syntax_tools/test/syntax_tools_SUITE.erl
index fd381f0b25..9eef56bddb 100644
--- a/lib/syntax_tools/test/syntax_tools_SUITE.erl
+++ b/lib/syntax_tools/test/syntax_tools_SUITE.erl
@@ -24,12 +24,12 @@
 	 init_per_group/2,end_per_group/2]).
 
 %% Test cases
--export([smoke_test/1]).
+-export([smoke_test/1,revert/1]).
 
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
-    [smoke_test].
+    [smoke_test,revert].
 
 groups() -> 
     [].
@@ -79,6 +79,31 @@ print_error_markers(F, File) ->
     end.
     
 
+%% Read with erl_parse, wrap and revert with erl_syntax and check for equality.
+revert(Config) when is_list(Config) ->
+    Dog = ?t:timetrap(?t:minutes(12)),
+    Wc = filename:join([code:lib_dir("stdlib"),"src","*.erl"]),
+    Fs = filelib:wildcard(Wc),
+    Path = [filename:join(code:lib_dir(stdlib), "include"),
+            filename:join(code:lib_dir(kernel), "include")],
+    io:format("~p files\n", [length(Fs)]),
+    case p_run(fun (File) -> revert_file(File, Path) end, Fs) of
+        0 -> ok;
+        N -> ?line ?t:fail({N,errors})
+        end,
+    ?line ?t:timetrap_cancel(Dog).
+
+revert_file(File, Path) ->
+    case epp:parse_file(File, Path, []) of
+        {ok,Fs0} ->
+            Fs1 = erl_syntax:form_list(Fs0),
+            Fs2 = erl_syntax_lib:map(fun (Node) -> Node end, Fs1),
+            Fs3 = erl_syntax:form_list_elements(Fs2),
+            Fs4 = [ erl_syntax:revert(Form) || Form <- Fs3 ],
+            {ok,_} = compile:forms(Fs4, [report,strong_validation]),
+            ok
+    end.
+
 p_run(Test, List) ->
     N = erlang:system_info(schedulers),
     p_run_loop(Test, List, N, [], 0).