Example of using TestFX

This example project shows the use of TestFX. It is based on the example provided by the TestFX community documentation. It takes the example further by separating out the Scene information into a separate class and adds some further tests.

Structure of the Application

The application code is found in src/main/java. It contains a single class, ExampleGridScene. This is a subclass of the JavaFX Scene class. The ExampleGridScene adds a GridPane as the root element. Two buttons are then added into the root element.

Each button has an ID. This is a string label. It is used by the tests as a way to find the relevant button and interact with it during the testing stage.

The first button simple changes its label once it has been pressed. The label is changed to the same value whenever it is pressed.

The second button has label with the format <numberOfClicks> clicks. It starts with the value 0 clicks. Each time it is pressed, the value will change to represent the click count. For example, after two clicks, the value will be 2 clicks.

Structure of the Test

The test class is found in src/test/java. The class is setup to use JUnit 5 and the Hamcrest matchers. Each test is marked with the @Test annotation.

There is a method at the top of the class that is used to start the Graphical User Interface (GUI) panel for each test. It has the @Start annotation, which comes from the TestFX package for JUnit5 integration. The @Start method is passed a JavaFX Stage. The GUI panel is to be placed into that Stage and it is then shown.

The tests are using Hamcrest matchers, which provide alternative ways to write assertions; Hamcrest refers to these as flexible expressions of intent, rather than assertions. However, they amount to same thing. If a Hamcrest expression does not evaluate to true, the test will be recorded as failed.

An example Hamcrest matcher is verifyThat().

The tests can make use of a FXRobot class, which comes from the TestFX classes. This enables the code to interact with the UI, e.g. clicking on a specific button.

In order to identify controls to interact with, a CSS ID is used. For example, look at the following line of code.

verifyThat("#first-button", hasText("click me to change my name!"));

The first parameter is a Node Query, i.e. a way to find an element in the GUI. There are different ways to perform this query, but this code is using CSS IDs. That is, it must start with a # character and is followed by a string of characters. In this code, this matches the names set using setId() in the ExampleGridScene class.

Building and running the project

The focus of this project is to run the tests. The Maven pom.xml is setup with the necessary dependencies to allow that to happen. There is no main() method, so this program cannot currently run other than through the tests.

To run the program from the command line, use mvn test.

The project can also be imported into environments such as Eclipse and IntelliJ IDEA.

Further information about TestFX

The TestFX community has a Wiki and also discusses issues on Gitter. See the TestFX pages for further information.