Fix assertion errors with more than 1 pinned var

Signed-off-by: José Valim <[email protected]>

Author: ericentin

lib/ex_unit/lib/ex_unit/assertions.ex

@@ -353,15 +353,17 @@ defmodule ExUnit.Assertions do
 
   defp pinned_vars([]), do: ""
   defp pinned_vars(pins) do
-    content = Enum.map(pins, fn(var) ->
+    content = Enum.reverse(pins)
+    |> Enum.uniq_by(&elem(&1, 0))
+    |> Enum.map(fn(var) ->
       binary = Macro.to_string(var)
       quote do
         "\n  " <> unquote(binary) <> " = " <> inspect(unquote(var))
       end
     end)
 
     quote do
-      "\nThe following variables were pinned:" <> unquote_splicing(content)
+      <<"\nThe following variables were pinned:", unquote_splicing(content)>>
     end
   end
 
@@ -384,7 +386,7 @@ defmodule ExUnit.Assertions do
       assert_raise ArithmeticError, "bad argument in arithmetic expression", fn ->
         1 + "test"
       end
-      
+
       assert_raise RuntimeError, ~r/^Today's lucky number is 0\.\d+!$/, fn ->
         raise "Today's lucky number is #{:random.uniform}!"
       end

lib/ex_unit/test/ex_unit/assertions_test.exs

@@ -127,6 +127,46 @@ defmodule ExUnit.AssertionsTest do
     end
   end
 
+  test "assert received with multiple identical pinned variables" do
+    status = :valid
+    send self(), {:status, :invalid, :invalid}
+    try do
+      "This should never be tested" = assert_received {
+        :status,
+        ^status,
+        ^status
+      }
+    rescue
+      error in [ExUnit.AssertionError] ->
+        "No message matching {:status, ^status, ^status} after 0ms.\n" <>
+        "The following variables were pinned:\n" <>
+        "  status = :valid\n" <>
+        "Process mailbox:\n" <>
+        "  {:status, :invalid, :invalid}" = error.message
+    end
+  end
+
+  test "assert received with multiple unique pinned variables" do
+    status = :valid
+    other_status = :invalid
+    send self(), {:status, :invalid, :invalid}
+    try do
+      "This should never be tested" = assert_received {
+        :status,
+        ^status,
+        ^other_status
+      }
+    rescue
+      error in [ExUnit.AssertionError] ->
+        "No message matching {:status, ^status, ^other_status} after 0ms.\n" <>
+        "The following variables were pinned:\n" <>
+        "  status = :valid\n" <>
+        "  other_status = :invalid\n" <>
+        "Process mailbox:\n" <>
+        "  {:status, :invalid, :invalid}" = error.message
+    end
+  end
+
   test "assert received when empty mailbox" do
     try do
       "This should never be tested" = assert_received :hello