From e1a74e3077ca870520a748f29dd7c4b9115ce090 Mon Sep 17 00:00:00 2001
From: Raimo Niskanen <raimo@erlang.org>
Date: Mon, 3 Apr 2017 12:29:23 +0200
Subject: Clean up documentation and test cases

---
 lib/stdlib/test/rand_SUITE.erl | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

(limited to 'lib/stdlib/test/rand_SUITE.erl')

diff --git a/lib/stdlib/test/rand_SUITE.erl b/lib/stdlib/test/rand_SUITE.erl
index fe5eaccda5..098eefeb61 100644
--- a/lib/stdlib/test/rand_SUITE.erl
+++ b/lib/stdlib/test/rand_SUITE.erl
@@ -356,14 +356,23 @@ basic_normal_1(0, {#{type:=Alg}, _}, Sum, SumSq) ->
 
 %% Test that the user can write algorithms.
 plugin(Config) when is_list(Config) ->
-    _ = lists:foldl(fun(_, S0) ->
-			    {V1, S1} = rand:uniform_s(10000, S0),
-			    true = is_integer(V1),
-			    {V2, S2} = rand:uniform_s(S1),
-			    true = is_float(V2),
-			    S2
-		    end, crypto_seed(), lists:seq(1, 200)),
-    ok.
+    try crypto:strong_rand_bytes(1) of
+        <<_>> ->
+            _ = lists:foldl(
+                  fun(_, S0) ->
+                          {V1, S1} = rand:uniform_s(10000, S0),
+                          true = is_integer(V1),
+                          {V2, S2} = rand:uniform_s(S1),
+                          true = is_float(V2),
+                          S2
+                  end, crypto_seed(), lists:seq(1, 200)),
+            ok
+    catch
+        error:low_entropy ->
+            {skip,low_entropy};
+        error:undef ->
+            {skip,no_crypto}
+    end.
 
 %% Test implementation
 crypto_seed() ->
@@ -397,7 +406,13 @@ crypto_uniform_n(N, State0) ->
 measure(Suite) when is_atom(Suite) -> [];
 measure(_Config) ->
     ct:timetrap({minutes,15}), %% valgrind needs a lot of time
-    Algos = [crypto64|algs()],
+    Algos =
+        try crypto:strong_rand_bytes(1) of
+            <<_>> -> [crypto64]
+        catch
+            error:low_entropy -> [];
+            error:undef -> []
+        end ++ algs(),
     io:format("RNG uniform integer performance~n",[]),
     _ = measure_1(random, fun(State) -> {int, random:uniform_s(10000, State)} end),
     _ = [measure_1(Algo, fun(State) -> {int, rand:uniform_s(10000, State)} end) || Algo <- Algos],
-- 
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