Attempt to fix an intermittent failure in GUI tests (#625)

Move to using pyqt's qtbot fixture instead of a hand-rolled
wait function

gui/tests/__init__.py

@@ -1,27 +1,3 @@
-from contextlib import contextmanager
-
-from PySide2.QtCore import QEventLoop, QTimer
 from PySide2.QtWidgets import QApplication
 
 APP = QApplication([])  # we need an application to create widgets
-
-
-@contextmanager
-def wait_signal(signal, timeout=5):
-    """Block loop until signal emitted, or timeout (s) elapses."""
-    loop = QEventLoop()
-    signal.connect(loop.quit)
-
-    yield
-
-    timed_out = []
-    if timeout is not None:
-
-        def quit_with_error():
-            timed_out.append(1)
-            loop.quit()
-
-        QTimer.singleShot(timeout * 1000, quit_with_error)
-    loop.exec_()
-    if timed_out:
-        assert False, "Timeout while waiting for %s" % signal

gui/tests/test_build_runner.py

@@ -1,5 +1,4 @@
 import os
-import shutil
 import tempfile
 import time
 import unittest
@@ -12,8 +11,6 @@
 from mozregression.persist_limit import PersistLimit
 from mozregui import build_runner
 
-from . import wait_signal
-
 
 @pytest.fixture(autouse=True)
 def mock_send_telemetry_ping():
@@ -40,40 +37,6 @@ def iter_content(chunk_size=4):
     response.iter_content = iter_content
 
 
-class TestGuiBuildDownloadManager(unittest.TestCase):
-    def setUp(self):
-        self.session, self.session_response = mock_session()
-        tmpdir = tempfile.mkdtemp()
-        tpersist = PersistLimit(10 * 1073741824)
-        self.addCleanup(shutil.rmtree, tmpdir)
-        self.dl_manager = build_runner.GuiBuildDownloadManager(tmpdir, tpersist)
-        self.dl_manager.session = self.session
-        self.signals = {}
-        for sig in ("download_progress", "download_started", "download_finished"):
-            self.signals[sig] = Mock()
-            getattr(self.dl_manager, sig).connect(self.signals[sig])
-
-    @patch("mozregui.build_runner.GuiBuildDownloadManager._extract_download_info")
-    def test_focus_download(self, extract_info):
-        extract_info.return_value = ("http://foo", "foo")
-        mock_response(self.session_response, b"this is some data" * 10000, 0.01)
-        build_info = Mock()
-
-        with wait_signal(self.dl_manager.download_finished):
-            self.dl_manager.focus_download(build_info)
-
-        # build_path is defined
-        self.assertEqual(build_info.build_file, self.dl_manager.get_dest("foo"))
-
-        # signals have been emitted
-        self.assertEqual(self.signals["download_started"].call_count, 1)
-        self.assertEqual(self.signals["download_finished"].call_count, 1)
-        self.assertGreater(self.signals["download_progress"].call_count, 0)
-
-        # well, file has been downloaded finally
-        self.assertTrue(os.path.isfile(build_info.build_file))
-
-
 class TestGuiTestRunner(unittest.TestCase):
     def setUp(self):
         self.evaluate_started = Mock()
@@ -108,6 +71,42 @@ def test_basic(self, create_launcher):
         self.assertEqual(self.test_runner.verdict, "g")
 
 
+@pytest.fixture()
+def mock_extract_info():
+    with patch("mozregui.build_runner.GuiBuildDownloadManager._extract_download_info") as p:
+        yield p
+
+
+def test_gui_build_download_manager_focus_download(qtbot, mock_extract_info):
+    session, session_response = mock_session()
+    with tempfile.TemporaryDirectory() as tmpdir:
+        tpersist = PersistLimit(10 * 1073741824)
+        dl_manager = build_runner.GuiBuildDownloadManager(tmpdir, tpersist)
+        dl_manager.session = session
+        signals = {}
+        for sig in ("download_progress", "download_started", "download_finished"):
+            signals[sig] = Mock()
+            getattr(dl_manager, sig).connect(signals[sig])
+
+        mock_extract_info.return_value = ("http://foo", "foo")
+        mock_response(session_response, b"this is some data" * 10000, 0.01)
+        build_info = Mock()
+
+        with qtbot.waitSignal(dl_manager.download_finished, raising=True):
+            dl_manager.focus_download(build_info)
+
+        # build_path is defined
+        assert build_info.build_file == dl_manager.get_dest("foo")
+
+        # signals have been emitted
+        assert signals["download_started"].call_count == 1
+        assert signals["download_finished"].call_count == 1
+        assert signals["download_progress"].call_count == 12
+
+        # well, file has been downloaded finally
+        assert os.path.isfile(build_info.build_file)
+
+
 def test_abstract_build_runner(qtbot):
     main_thread = QThread.currentThread()