Add test that constructs a QWidget

pytest_twisted.py

@@ -265,6 +265,9 @@ def init_default_reactor():
 
 
 def init_qt5_reactor():
+    import pytestqt.plugin
+    next(pytestqt.plugin.qapp(pytestqt.plugin.qapp_args()))
+
     import qt5reactor
 
     _install_reactor(
@@ -316,6 +319,7 @@ def pytest_addoption(parser):
     )
 
 
+@pytest.mark.trylast
 def pytest_configure(config):
     pytest.inlineCallbacks = _deprecate(
         deprecated='pytest.inlineCallbacks',

testing/test_basic.py

@@ -536,16 +536,22 @@ def test_succeed():
     """
     testdir.makepyfile(test_file)
     rr = testdir.run(sys.executable, "-m", "pytest", "-v", *cmd_opts)
-    assert "WrongReactorAlreadyInstalledError" in rr.stderr.str()
+    error_text = "WrongReactorAlreadyInstalledError"
+    assert (
+        error_text in rr.stderr.str() or
+        error_text in rr.stdout.str()
+    )
 
 
 def test_blockon_in_hook_with_qt5reactor(testdir, cmd_opts, request):
     skip_if_reactor_not(request, "qt5reactor")
     conftest_file = """
+    import pytest
     import pytest_twisted as pt
     import pytestqt
     from twisted.internet import defer
 
+    @pytest.mark.trylast
     def pytest_configure(config):
         pt.init_qt5_reactor()
         d = defer.Deferred()
@@ -583,7 +589,11 @@ def test_succeed():
     """
     testdir.makepyfile(test_file)
     rr = testdir.run(sys.executable, "-m", "pytest", "-v", *cmd_opts)
-    assert "WrongReactorAlreadyInstalledError" in rr.stderr.str()
+    error_text = "WrongReactorAlreadyInstalledError"
+    assert (
+        error_text in rr.stderr.str() or
+        error_text in rr.stdout.str()
+    )
 
 
 def test_pytest_from_reactor_thread(testdir, request):
@@ -696,3 +706,25 @@ def test_succeed():
     testdir.makepyfile(test_file)
     rr = testdir.run(sys.executable, "-m", "pytest", "-v", *cmd_opts)
     assert "WrongReactorAlreadyInstalledError" in rr.stderr.str()
+
+
+qt_fixtures = ('qapp', 'qtbot', 'nothing')
+
+
+@pytest.mark.parametrize("fixture", qt_fixtures, ids=qt_fixtures)
+def test_qwidget(testdir, cmd_opts, fixture, request):
+    skip_if_reactor_not(request, "qt5reactor")
+    test_file = """
+    import pytest
+    from PyQt5 import QtWidgets
+
+    @pytest.fixture
+    def nothing():
+        return
+
+    def test_construct_qwidget({fixture}):
+        QtWidgets.QWidget()
+    """.format(fixture=fixture)
+    testdir.makepyfile(test_file)
+    rr = testdir.run(sys.executable, "-m", "pytest", "-v", *cmd_opts)
+    assert rr.ret == 0