How to unit test a JavaFx property binding?

Question

I am using OpenJFX 13 with a presentation model that has DoubleProperty field that gets updated like this:

public class MyPresentationModel {
    private DoubleProperty batteryLevel = new SimpleDoubleProperty<>(100.0);

    public void setBatteryLevel(double value) {
        Platform.runLater( () -> 
        batteryLevel.setValue(value) );
    }
}

The Platform.runLater is needed because the setter can be called from any thread.

If I now want to test this is a simple unit test (Using JUnit 5 with AssertJ), the test fails because the JavaFX toolkit is not initialized.

No problem, I add TestFX to my project and update the test to:

@ExtendWith(ApplicationExtension.class)
class MyPresentationModelTest {
    @Test
    void test() {
        MyPresentationModel pm = new MyPresentationModel();
        pm.setBatteryLevel(75.0);
        assertThat(pm.batteryLevelProperty().get()).isCloseTo(75.0, Offset.offset(0.1));

    }
}

Result:

java.lang.AssertionError: 
Expecting:
  <100.0>
to be close to:
  <75.0>
by less than <0.1> but difference was <25.0>.
(a difference of exactly <0.1> being considered valid)

Which is logical given the fact that the update is done on the JavaFx thread.

So how do I wait until the JavaFx thread has updated the property so I can assert the value?