Improve i/o handling in keypress listener (#21)

- If something goes wrong when listing for key presses, make sure the
  exception gets reported. This was hiding legitimate errors.
- Don't attempt to use `IO#raw` if the input is not a TTY.
- If there aren't any characters left in stdin (as is the case when unit
  testing with `StringIO`), exit the listener loop. This speeds up unit
  tests dramatically.

lib/mighty_test/console.rb

@@ -16,7 +16,7 @@ def clear
     end
 
     def wait_for_keypress
-      return stdin.getc unless stdin.respond_to?(:raw)
+      return stdin.getc unless stdin.respond_to?(:raw) && tty?
 
       stdin.raw(intr: true) { stdin.getc }
     end

lib/mighty_test/watcher.rb

@@ -96,11 +96,12 @@ def start_keypress_listener
       @keypress_listener = Thread.new do
         loop do
           key = console.wait_for_keypress
-          post_event(:keypress, key) if key
-        rescue Interrupt
-          retry
+          break if key.nil?
+
+          post_event(:keypress, key)
         end
       end
+      @keypress_listener.abort_on_exception = true
     end
 
     def loop_for(iterations, &)

test/integration/mt_test.rb

@@ -57,9 +57,9 @@ def test_mt_runs_no_tests_if_line_number_doesnt_match
       refute_match(/FailingTest/, result.stdout)
     end
 
-    def test_mt_runs_watch_mode_that_executes_tests_when_files_change
+    def test_mt_runs_watch_mode_that_executes_tests_when_files_change # rubocop:disable Minitest/MultipleAssertions
       project_dir = fixtures_path.join("example_project")
-      stdout, = capture_subprocess_io do
+      stdout, stderr = capture_subprocess_io do
         # Start mt --watch in the background
         pid = spawn(*%w[bundle exec mt --watch --verbose], chdir: project_dir)
 
@@ -75,6 +75,7 @@ def test_mt_runs_watch_mode_that_executes_tests_when_files_change
       end
 
       assert_includes(stdout, "Watching for changes to source and test files.")
+      assert_empty(stderr)
       assert_match(/ExampleTest/, stdout)
       assert_match(/\d runs, \d assertions, 0 failures, 0 errors/, stdout)
     end

test/mighty_test/watcher_test.rb

@@ -205,7 +205,7 @@ def paused?
 
     def run_watcher(iterations: :indefinitely, in: ".", extra_args: [], stdin: nil, file_system: FileSystem.new)
       listen_thread = @listen_thread
-      console = Console.new(stdin: stdin.nil? ? StringIO.new("") : StringIO.new(stdin))
+      console = Console.new(stdin: stdin.nil? ? StringIO.new : StringIO.new(stdin))
       console.define_singleton_method(:clear) { puts "[CLEAR]" }
       console.define_singleton_method(:play_sound) { |sound| puts "[SOUND] #{sound.inspect}" }
       file_system.define_singleton_method(:listen) { |&callback| Listener.new(listen_thread, callback) }