Testing psygnal with pytest-qt

[jacopoabramo]

• psygnal version: 0.11.1
• Python version: 3.10
• Operating System: Windows

For a project I'm working on, I'm using psygnal as signaling mechanism within my application. I would like to run unit tests on some internal parts of my project to ensure everything works properly. Is it possible to use pytest-qt together with psygnal to run unit tests and ensure that signals are correctly emitted?

[jacopoabramo]

Just answered myself by checking the local unit tests and the answer seems yes. Closing.

[tlambert03]

Yep! As you found, it works. I'll also note the long standing #46 "todo"... but that hasn't been urgent for me since I too just use pytest-qt in most cases

[tlambert03]

Another test pattern for synchronous applications is to connect your signal to a Mock(), perform your action, and then use mock.assert_called...

[jacopoabramo]

Another test pattern for synchronous applications is to connect your signal to a Mock(), perform your action, and then use mock.assert_called...

Do you have an example I can look at?

[tlambert03]

yeah, that pattern is used all throughout the tests in this repo, for example:

psygnal/tests/test_psygnal.py

Lines 109 to 120 in 8f4d781

	def test_basic_signal():
	"""standard Qt usage, as class attribute"""
	emitter = Emitter()
	mock = MagicMock()
	emitter.one_int.connect(mock)
	emitter.one_int.emit(1)
	mock.assert_called_once_with(1)
	mock.reset_mock()
	# calling directly also works
	emitter.one_int(1)
	mock.assert_called_once_with(1)

(note, it really doesn't need to be MagicMock there... a simple Mock() would also work fine)

[jacopoabramo]

Ah so you're mixing both unittest and pytest together. Clever, I might pick up on that since in the end I'm also using mock objects to test my logic. Thanks!

[tlambert03]

yeah, one doesn't need to be using unittest as a test runner to take advantage of patch and mock. Those are just generally useful objects regardless of your test runner