My GUI unit-tests with Assertj Swing (version 3.17.0) all pass locally, but sometimes they fail in a CI server. If i retry long enough, eventually the test suite becomes green. I'm having a hard time figuring out how to fix these tests.
I am using Java 8 and Github Actions as CI. As suggested in a similar question, I am using VNC to run these tests headlessly on CI, with the command:
./execute-on-vnc.sh mvn -B -f pom.xml clean verify
Here's an example of a test that is failing (I am mocking the controller and just verifying that clicking a button actually calls the controller method with the correct arguments):
@Mock private ItemController controller;
@Test @GUITest
public void testAddItemButtonShouldDelegateToControllerAddItem() {
window.textBox("itemIdTextField").enterText("1");
window.textBox("itemNameTextField").enterText("Some Item");
window.button(JButtonMatcher.withName("addItemButton")).click();
verify(controller).addItem(new Item("1", "Some Item"));
}
Here's the very straight forward code for handling clicks on the JButton:
addItemButton.addActionListener(e ->
controller.addItem(new Item(itemIdTextField.getText(), itemNameTextField.getText()))
);
The test passes locally every time with no issues, but often fails on CI with this error:
testAddItemButtonShouldDelegateToControllerAddItem(com.example.view.swing.ItemSwingViewTest)
Time elapsed: 0.985 sec <<< FAILURE!
Wanted but not invoked:
controller.addItem(
Item{id='1', name='Some Item'}
);
Actually, there were zero interactions with this mock.
I have not been able to figure out the cause of these flaky tests.
Things I've tried:
- Added 5 seconds timeouts to verify() methods
- Invalidated CI maven cache and rerun tests
- Tested on CI with other Java versions (9, 11 and 13)
All with no luck. Am I doing something wrong?