Why does javafx Alert showAndWait gets called in mock?

Question

I want to test that Alert showAndWait() method gets called. I mock Alert with Mockito and verify if showAndWait() was called. But the problem is Alert.showAndWait() ACTUALLY gets called, instead of mocked method. I assume this should NOT happen.

My code:

package drakonli.jcomponents.notificator;

import javafx.scene.control.Alert;
import junit_util.JavaFXThreadingRule;
import org.junit.Rule;
import org.junit.Test;

import static org.mockito.Mockito.mock;

    public class AlertTest
    {
        @Rule public JavaFXThreadingRule javafxRule = new JavaFXThreadingRule();

        @Test
        public void success()
        {
            Alert alert = mock(Alert.class);

            alert.showAndWait();

            verify(alert, atLeastOnce()).showAndWait();
        }
    }

Exception:

java.lang.NullPointerException
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.control.Dialog.showAndWait(Dialog.java:331)
    at drakonli.jcomponents.notificator.AlertNotificatorTest.success(AlertNotificatorTest.java:30)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at junit_util.JavaFXThreadingRule$OnJFXThreadStatement$1.run(JavaFXThreadingRule.java:65)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    at java.lang.Thread.run(Thread.java:748)

indeed it is. And also it's a parent method: https://docs.oracle.com/javase/8/javafx/api/javafx/scene/control/Dialog.html#showAndWait-- — drakonli, Aug 25 '18 at 22:37
Mockito can't override final methods, effectively mockito works by creating an extension of the object being m,ocked — Darren Forsythe, Aug 25 '18 at 22:44
Ye, after your answer I googled it. Great, thanks. Post an answer and I will mark as the correct one :) — drakonli, Aug 25 '18 at 22:45
Possible duplicate of [Final method mocking](https://stackoverflow.com/questions/3793791/final-method-mocking) — Slaw, Aug 25 '18 at 22:57
You might want to look into [TextFX](https://github.com/TestFX/TestFX) (not sure it will help here). — Slaw, Aug 25 '18 at 22:58
Thanks, ye I know about that, but it's not really about mocking, more about "frontend" testing — drakonli, Aug 25 '18 at 23:08

score 1 · Accepted Answer · answered Aug 25 '18 at 22:53

Mockito cannot mock Final methods or classes. Powermock can, but I do not recommended for any new functionality (it gets overused, or used incorrectly). I'd recommened looking for test harnesses for the framework or working around the limitations and acceptable that some stuff cannot be effectively tested.

Why does javafx Alert showAndWait gets called in mock?

1 Answers1