Ensure Mix.Shell.IO do not puke on :eof

Author: José Valim

lib/mix/lib/mix/shell/io.ex

@@ -38,10 +38,17 @@ defmodule Mix.Shell.IO do
   """
   def yes?(message) do
     put_app
-    IO.gets(message <> IO.ANSI.escape(" [Yn] ")) =~ %r/^(Y(es)?)?$/i
+    got_yes? IO.gets(message <> IO.ANSI.escape(" [Yn] "))
   end
 
-  def put_app do
+  defp got_yes?(answer) when is_binary(answer) do
+    answer =~ %r/^(Y(es)?)?$/i
+  end
+
+  # The io server may return :eof or :error
+  defp got_yes?(_), do: false
+
+  defp put_app do
     if Mix.Shell.output_app? do
       IO.puts "==> #{Mix.project[:app]}"
     end

lib/mix/test/mix/shell/io_test.exs

@@ -0,0 +1,31 @@
+Code.require_file "../../test_helper.exs", __DIR__
+
+defmodule Mix.Shell.IOTest do
+  use MixTest.Case, async: true
+
+  import ExUnit.CaptureIO
+  import Mix.Shell.IO
+
+  test "prints info message to stdio" do
+    assert capture_io(fn ->
+      info "hello"
+    end) == "hello\n"
+  end
+
+  test "prints error message to stderr" do
+    assert capture_io(:stderr, fn ->
+      error "hello"
+    end) =~ "hello"
+  end
+
+  test "asks the user with yes?" do
+    assert capture_io("\n", fn -> yes?("Ok?") end) == "Ok? [Yn] "
+    assert capture_io("\n", fn -> assert yes?("Ok?") end)
+    assert capture_io("Yes", fn -> assert yes?("Ok?") end)
+    assert capture_io("yes", fn -> assert yes?("Ok?") end)
+    assert capture_io("y", fn -> assert yes?("Ok?") end)
+
+    assert capture_io("n", fn -> refute yes?("Ok?") end)
+    assert capture_io("", fn -> refute yes?("Ok?") end)
+  end
+end