Ensure shell is reverted after mix test run

Author: José Valim

lib/mix/lib/mix/cli.ex

@@ -85,7 +85,7 @@ defmodule Mix.CLI do
       # We only rescue exceptions in the Mix namespace, all
       # others pass through and will explode on the users face
       exception ->
-        if Map.get(exception, :mix) && not Mix.debug?() do
+        if Map.get(exception, :mix, false) and not Mix.debug?() do
           mod = exception.__struct__ |> Module.split() |> Enum.at(0, "Mix")
           Mix.shell().error("** (#{mod}) #{Exception.message(exception)}")
           exit({:shutdown, 1})

lib/mix/lib/mix/tasks/test.ex

@@ -421,8 +421,10 @@ defmodule Mix.Tasks.Test do
       {:error, {:already_loaded, :ex_unit}} -> :ok
     end
 
-    # Then configure ExUnit again so that command line options
-    # override test_helper.exs
+    # The test helper may change the Mix.shell(), so let's make sure to revert it later
+    shell = Mix.shell()
+
+    # Configure ExUnit now and then again so the task options override test_helper.exs
     {ex_unit_opts, allowed_files} = process_ex_unit_opts(opts)
     ExUnit.configure(ex_unit_opts)
 
@@ -442,20 +444,21 @@ defmodule Mix.Tasks.Test do
 
     display_warn_test_pattern(test_files, test_pattern, matched_test_files, warn_test_pattern)
 
-    case CT.require_and_run(matched_test_files, test_paths, opts) do
+    results = CT.require_and_run(matched_test_files, test_paths, opts)
+    Mix.shell(shell)
+
+    case results do
       {:ok, %{excluded: excluded, failures: failures, total: total}} ->
         cover && cover.()
 
-        option_only_present? = Keyword.has_key?(opts, :only)
-
         cond do
           failures > 0 and opts[:raise] ->
             Mix.raise("\"mix test\" failed")
 
           failures > 0 ->
             System.at_exit(fn _ -> exit({:shutdown, 1}) end)
 
-          excluded == total and option_only_present? ->
+          excluded == total and Keyword.has_key?(opts, :only) ->
             message = "The --only option was given to \"mix test\" but no test was executed"
             raise_or_error_at_exit(message, opts)
 
@@ -541,9 +544,15 @@ defmodule Mix.Tasks.Test do
   end
 
   defp merge_helper_opts(opts) do
+    # The only options that are additive from app env are the excludes
     merge_opts(opts, :exclude)
   end
 
+  defp merge_opts(opts, key) do
+    value = List.wrap(Application.get_env(:ex_unit, key, []))
+    Keyword.update(opts, key, value, &Enum.uniq(&1 ++ value))
+  end
+
   defp default_opts(opts) do
     # Set autorun to false because Mix
     # automatically runs the test suite for us.
@@ -643,11 +652,6 @@ defmodule Mix.Tasks.Test do
     end
   end
 
-  defp merge_opts(opts, key) do
-    value = List.wrap(Application.get_env(:ex_unit, key, []))
-    Keyword.update(opts, key, value, &Enum.uniq(&1 ++ value))
-  end
-
   defp require_test_helper(dir) do
     file = Path.join(dir, "test_helper.exs")
 

lib/mix/test/mix/tasks/test_test.exs

@@ -277,6 +277,20 @@ defmodule Mix.Tasks.TestTest do
       end)
     end
 
+    test "raises when no test runs even with Mix.shell() change" do
+      in_fixture("test_stale", fn ->
+        File.write!("test/test_helper.exs", """
+        Mix.shell(Mix.Shell.Process)
+        ExUnit.start()
+        """)
+
+        assert_run_output(
+          ["--only", "unknown"],
+          "The --only option was given to \"mix test\" but no test was executed"
+        )
+      end)
+    end
+
     test "raises an exception if line numbers are given with multiple files" do
       in_fixture("test_stale", fn ->
         assert_run_output(