mix test --listen-on-stdin will no longer exit on failure (#4930)

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: ericentin

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

@@ -175,6 +175,15 @@ defmodule Mix.Tasks.Test do
   def run(args) do
     {opts, files} = OptionParser.parse!(args, strict: @switches)
 
+    if opts[:listen_on_stdin] do
+      System.at_exit fn _ ->
+        IO.gets(:stdio, "")
+        Mix.shell.info "Restarting..."
+        :init.restart()
+        :timer.sleep(:infinity)
+      end
+    end
+
     unless System.get_env("MIX_ENV") || Mix.env == :test do
       Mix.raise "\"mix test\" is running on environment \"#{Mix.env}\". If you are " <>
                                 "running tests along another task, please set MIX_ENV explicitly"
@@ -246,13 +255,6 @@ defmodule Mix.Tasks.Test do
       :noop ->
         :ok
     end
-
-    if opts[:listen_on_stdin] do
-      IO.gets(:stdio, "")
-      Mix.shell.info "Restarting..."
-      :init.restart()
-      :timer.sleep(:infinity)
-    end
   end
 
   defp display_warn_test_pattern(files, pattern) do

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

@@ -116,6 +116,58 @@ defmodule Mix.Tasks.TestTest do
     end
   end
 
+  test "--listen-on-stdin: does not exit on compilation failure" do
+    in_fixture "test_stale", fn ->
+      File.write!("lib/b.ex", """
+      defmodule B do
+        def f, do: error_not_a_var
+      end
+      """)
+
+      port = mix_port(~w[test --listen-on-stdin])
+
+      assert receive_until_match(port, "error", []) =~ "lib/b.ex"
+
+      File.write!("lib/b.ex", """
+      defmodule B do
+        def f, do: A.f
+      end
+      """)
+
+      Port.command(port, "\n")
+
+      assert receive_until_match(port, "seed", []) =~ "2 tests"
+
+      File.write!("test/b_test_stale.exs", """
+      defmodule BTest do
+        use ExUnit.Case
+
+        test "f" do
+          assert B.f() == error_not_a_var
+        end
+      end
+      """)
+
+      Port.command(port, "\n")
+
+      assert receive_until_match(port, "undefined function error_not_a_var", []) =~ "test/b_test_stale.exs"
+
+      File.write!("test/b_test_stale.exs", """
+      defmodule BTest do
+        use ExUnit.Case
+
+        test "f" do
+          assert B.f() == :ok
+        end
+      end
+      """)
+
+      Port.command(port, "\n")
+
+      assert receive_until_match(port, "seed", []) =~ "2 tests"
+    end
+  end
+
   defp receive_until_match(port, expected, acc) do
     receive do
       {^port, {:data, charlist}} ->