ExUnit callbacks must return :ok or { :ok, data }

Author: José Valim

Diff for: lib/elixir/test/elixir/file_test.exs

@@ -13,13 +13,13 @@ defmodule FileTest do
     setup do
       src = fixture_path("cp_r")
       :file.make_symlink 'certainly/invalid', Path.join([src, "c"])
-      []
+      :ok
     end
 
     teardown do
       src = fixture_path("cp_r")
       File.rm Path.join([src, "c"])
-      []
+      :ok
     end
 
     test :cp_with_src_file_and_dest_file do
@@ -682,13 +682,13 @@ defmodule FileTest do
     setup do
       src = fixture_path("cp_r")
       :file.make_symlink 'certainly/invalid', Path.join([src, "c"])
-      []
+      :ok
     end
 
     teardown do
       src = fixture_path("cp_r")
       File.rm Path.join([src, "c"])
-      []
+      :ok
     end
 
     test :rm_file do

Diff for: lib/ex_unit/lib/ex_unit/callbacks.ex

@@ -14,8 +14,8 @@ defmodule ExUnit.Callbacks do
         setup do
           IO.puts "This is a setup callback"
 
-          # Return no extra meta data
-          [hello: "world"]
+          # Returns extra metadata
+          { :ok, [hello: "world"] }
         end
 
         setup context do
@@ -24,6 +24,9 @@ defmodule ExUnit.Callbacks do
 
           # The metadata returned by the previous setup as well
           assert context[:hello] == "world"
+
+          # No metadata
+          :ok
         end
 
         test "always pass" do
@@ -115,14 +118,21 @@ defmodule ExUnit.Callbacks do
 
   ## Helpers
 
+  def __merge__(_mod, other, :ok), do: other
+  def __merge__(_mod, other, { :ok, data }), do: Keyword.merge(other, data)
+  def __merge__(mod, _, failure) do
+    raise "expected ExUnit callback in #{inspect mod} to return :ok " <>
+          " or { :ok, data }, got #{inspect failure} instead"
+  end
+
   defp compile_callbacks(env, kind) do
     callbacks = Module.get_attribute(env.module, kind) |> Enum.reverse
 
     acc =
       Enum.reduce callbacks, quote(do: context), fn(callback, acc) ->
         quote do
           context = unquote(acc)
-          Keyword.merge(context, unquote(callback)(context))
+          unquote(__MODULE__).__merge__(__MODULE__, context, unquote(callback)(context))
         end
       end
 

Diff for: lib/ex_unit/test/ex_unit/callbacks_test.exs

@@ -4,17 +4,17 @@ defmodule ExUnit.CallbacksTest do
   use ExUnit.Case
 
   setup_all do
-    [context: :setup_all]
+    { :ok, [context: :setup_all] }
   end
 
   setup do
-    [initial_setup: true]
+    { :ok, [initial_setup: true] }
   end
 
   setup context do
     assert context[:initial_setup]
     assert context[:context] == :setup_all
-    [context: :setup]
+    { :ok, [context: :setup] }
   end
 
   setup context do
@@ -23,23 +23,23 @@ defmodule ExUnit.CallbacksTest do
     else
       Process.put(:ex_unit_callback, context[:test])
     end
-    []
+    :ok
   end
 
   teardown context do
     assert context[:context] == :setup
-    []
+    :ok
   end
 
   teardown context do
     assert Process.get(:ex_unit_callback) == context[:test]
     Process.delete(:ex_unit_callback)
-    []
+    :ok
   end
 
   teardown_all context do
     assert context[:context] == :setup_all
-    []
+    :ok
   end
 
   test "callbacks can run custom code" do

Diff for: lib/ex_unit/test/ex_unit/case_template_test.exs

@@ -14,22 +14,22 @@ defmodule ExUnit.SampleCase do
   end
 
   setup_all do
-    [context: :setup_all]
+    { :ok, [context: :setup_all] }
   end
 
   setup context do
     assert context[:context] == :setup_all
-    [context: :setup]
+    { :ok, [context: :setup] }
   end
 
   teardown context do
     assert context[:context] == :setup
-    []
+    :ok
   end
 
   teardown_all context do
     assert context[:context] == :setup_all
-    []
+    :ok
   end
 end
 

Diff for: lib/mix/test/test_helper.exs

@@ -59,7 +59,7 @@ defmodule MixTest.Case do
         Mix.Deps.Converger.clear_cache
         System.put_env("MIX_HOME", tmp_path(".mix"))
         del_tmp_paths
-        []
+        :ok
       end
     end
   end