From: Peter Lemenkov <lemenkov@gmail.com>
Date: Fri, 9 Sep 2016 15:30:47 +0300
Subject: [PATCH] Don't use deprecated funs in Erlang 18

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>

diff --git a/src/oauth2_token.erl b/src/oauth2_token.erl
index 4030f9b..19ec966 100644
--- a/src/oauth2_token.erl
+++ b/src/oauth2_token.erl
@@ -26,9 +26,6 @@
 %%%_ * API -------------------------------------------------------------
 -export([generate/1]).
 
-%%% Exported for testability
--export([strong_rand_bytes_proxy/1]).
-
 %%%_* Macros ===========================================================
 -define(TOKEN_LENGTH, 32).
 
@@ -42,7 +39,7 @@ generate(_Context) -> generate_fragment(?TOKEN_LENGTH).
 -spec generate_fragment(integer()) -> binary().
 generate_fragment(0) -> <<>>;
 generate_fragment(N) ->
-    Rand = base64:encode(rand_bytes(N)),
+    Rand = base64:encode(crypto:strong_rand_bytes(N)),
     Frag = << <<C>> || <<C>> <= <<Rand:N/bytes>>, is_alphanum(C) >>,
     <<Frag/binary, (generate_fragment(N - byte_size(Frag)))/binary>>.
 
@@ -53,25 +50,6 @@ is_alphanum(C) when C >= 16#41 andalso C =< 16#5A -> true;
 is_alphanum(C) when C >= 16#61 andalso C =< 16#7A -> true;
 is_alphanum(_)                                    -> false.
 
-%% @doc Generate N random bytes, using the crypto:strong_rand_bytes
-%%      function if sufficient entropy exists. If not, use crypto:rand_bytes
-%%      as a fallback.
--spec rand_bytes(non_neg_integer()) -> binary().
-rand_bytes(N) ->
-    try
-        %% NOTE: Apparently we can't meck away the crypto module,
-        %% so we install this proxy to allow for testing the low_entropy
-        %% situation.
-        ?MODULE:strong_rand_bytes_proxy(N)
-    catch
-        throw:low_entropy ->
-            crypto:rand_bytes(N)
-    end.
-
-%% @equiv crypto:strong_rand_bytes(N)
--spec strong_rand_bytes_proxy(non_neg_integer()) -> binary().
-strong_rand_bytes_proxy(N) -> crypto:strong_rand_bytes(N).
-
 %%%_* Tests ============================================================
 -ifdef(TEST).
 -include_lib("eunit/include/eunit.hrl").
diff --git a/test/oauth2_token_tests.erl b/test/oauth2_token_tests.erl
index 77e11ed..bc3389e 100644
--- a/test/oauth2_token_tests.erl
+++ b/test/oauth2_token_tests.erl
@@ -44,23 +44,12 @@ generate_test() ->
     ?assert(lists:all(fun is_alphanum/1, binary_to_list(Token))).
 
 generate_low_entropy_test_() ->
-    {setup,
-     fun() ->
-             meck:new(oauth2_token, [passthrough]),
-             meck:expect(oauth2_token, strong_rand_bytes_proxy,
-                         fun(_) -> throw(low_entropy) end)
-     end,
-     fun(_) ->
-             meck:unload(oauth2_token)
-     end,
-     fun(_) ->
-             [
-              ?_assertEqual(byte_size(oauth2_token:generate([])), 32),
-              ?_assert(
-                 lists:all(fun is_alphanum/1,
-                           binary_to_list(oauth2_token:generate([]))))
-             ]
-     end}.
+     [
+      ?_assertEqual(byte_size(oauth2_token:generate([])), 32),
+      ?_assert(
+	 lists:all(fun is_alphanum/1,
+		   binary_to_list(oauth2_token:generate([]))))
+     ].
 
 %%%===================================================================
 %%% Utility functions