assert_receive(d) should leak

Closes #2030.

Author: ericmj

lib/ex_unit/lib/ex_unit/assertions.ex

@@ -308,7 +308,7 @@ defmodule ExUnit.Assertions do
 
     quote do
       receive do
-        unquote(expected) = received -> received
+        unquote(expected) = received -> unquote(expected) = received
       after
         unquote(timeout) ->
           flunk unquote(message) || "Expected to have received message matching #{unquote binary}"

lib/ex_unit/test/ex_unit/assertions_test.exs

@@ -89,6 +89,12 @@ defmodule ExUnit.AssertionsTest do
     end
   end
 
+  test "assert received leaks" do
+    send self, { :hello, :world }
+    assert_received { :hello, world }
+    :world = world
+  end
+
   test "refute received does not wait" do
     false = refute_received :hello
   end