Tag all doctest tests

Author: José Valim

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Enhancements
   * [ExUnit] Print process mailbox on failing `assert_receive`
+  * [ExUnit] Tag all doctests with the `:doctest` tag
   * [Mix] `mix deps.unlock` warns when given missing dependency
   * [Kernel] Friendlier `unquote_splicing` error on inline quote
 

lib/ex_unit/lib/ex_unit/doc_test.ex

@@ -152,6 +152,7 @@ defmodule ExUnit.DocTest do
     tests = quote bind_quoted: binding do
       file = "(for doctest at) " <> Path.relative_to_cwd(mod.__info__(:compile)[:source])
       for {name, test} <- ExUnit.DocTest.__doctests__(mod, opts) do
+        @tag :doctest
         @file file
         test name, do: unquote(test)
       end
@@ -348,9 +349,9 @@ defmodule ExUnit.DocTest do
 
     moduledocs = extract_from_moduledoc(all_docs[:moduledoc])
 
-    docs = for doc <- all_docs[:docs] do
-      extract_from_doc(doc)
-    end |> Enum.concat
+    docs = for doc <- all_docs[:docs],
+               doc <- extract_from_doc(doc),
+               do: doc
 
     moduledocs ++ docs
   end

lib/ex_unit/test/ex_unit/doc_test_test.exs

@@ -264,6 +264,20 @@ defmodule ExUnit.DocTestTest do
     """
   end
 
+  test "tags tests as doctests" do
+    defmodule DoctestTag do
+      use ExUnit.Case
+      doctest ExUnit.DocTestTest.NoImport
+
+      setup test do
+        assert test.doctest
+        :ok
+      end
+    end
+
+    assert capture_io(fn -> ExUnit.run end) =~ "1 tests, 0 failures"
+  end
+
   test "multiple exceptions in one test case is not supported" do
     assert_raise ExUnit.DocTest.Error, ~r"multiple exceptions in one doctest case are not supported", fn ->
       defmodule NeverCompiled do