1

Right now, I'm considering incorporating 100% code coverage into my project. However, I'm having trouble unit testing the main entry point of my code:

 public static void main(String[] args) {
      launch(args);
 }

This method is difficult to test because it launches an entirely new JavaFX program in the background. In addition to this behavior, a JavaFX program cannot be started more than once. Moreover, the documentation for javafx.application.Application explictly states that, "A JavaFX Application should not attempt to use JavaFX after the FX toolkit has terminated or from a ShutdownHook, that is, after the stop() method returns or System.exit(int) is called."

I am encountering this project because I'm also working with TestFX, a library that helps with clean testing for JavaFX. However, this library does not offer support for the testing of the main method, and as a result I have to write a workaround. There is a possibility of the developers of TestFX knowing about a possible workaround for this problem, for each and every unit tested method, a new instance of an Application is started. Perhaps there could be a way to completely shutdown and reset all variables of a JavaFX program.

To be fair, this method is not that significant to test, however it would be pleasant to have 100% code coverage. It would be entirely reasonable to not test this method as well. The full class can be found below:

package com.meti.app;

import javafx.application.Application;
import javafx.stage.Stage;

/**
 * @author SirMathhman
 * @version 0.0.0
 * @since 4/5/2019
 */ //Main MUST remain public in order for JavaFX Application to start.
public class Main extends Application {
    static InfinityImpl implementation = new Infinity();
    static Main instance;

    @Override
    public void start(Stage primaryStage) {
        instance = this;
        implementation.start(primaryStage);
    }

    @Override
    public void stop() {
        implementation.stop();
        instance = null;
    }

    public static void main(String[] args) {
        launch(args);
    }
}

The static variables above are irrelevant to the aforementioned question and are used for testing purposes in another class which ensures that the delegation works correctly. The application delegates most of the operations to a delegate class which makes the code easier to test.

Moreover, IntelliJ doesn't allow methods to be excluded during code testing. If you have any other questions, please let me know. Thank you!

Some additional reading:

  1. How to call launch() more than once in java
  2. https://github.com/TestFX/TestFX/blob/master/subprojects/testfx-core/src/main/java/org/testfx/api/FxToolkit.java
SirMathhman
  • 180
  • 3
  • 11
  • 6
    Unit testing methods that contain no logic is a waste of time. Spend the time developing features instead. – Dawood ibn Kareem Apr 07 '19 at 21:29
  • 2
    Like what @DawoodibnKareem mentioned, there is no real logic in `main()` - it's close to an attempt to test whether `String` class does its job correctly. You should start your testing from `start()`, specifically that `implementation.start()`. Side note: using `static` (i.e. globals) everywhere is going to be your biggest problem for unit testing, because it causes a lot of dependencies everywhere and one of the million modules you have could interfere with the module you are testing. – Jai Apr 08 '19 at 01:58

0 Answers0