Add tests for JavaFX

build.gradle

@@ -14,6 +14,9 @@ dependencies {
     implementation 'me.xdrop:fuzzywuzzy:1.4.0'
     testImplementation 'org.junit.jupiter:junit-jupiter:5.10.0'
     testImplementation 'org.mockito:mockito-core:5.10.0'
+    testImplementation 'org.testfx:testfx-junit5:4.0.18'
+    testImplementation 'org.assertj:assertj-core:3.25.3'
+    testImplementation 'org.hamcrest:hamcrest:2.2'
 }
 
 java {

src/test/java/convobot/gui/JavaFxTest.java

@@ -0,0 +1,66 @@
+package gui;
+
+// this code is taken from https://github.com/TestFX/TestFX
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.testfx.api.FxRobot;
+import org.testfx.assertions.api.Assertions;
+import org.testfx.framework.junit5.ApplicationExtension;
+import org.testfx.framework.junit5.Start;
+
+import javafx.scene.Scene;
+import javafx.scene.control.Button;
+import javafx.scene.layout.StackPane;
+import javafx.stage.Stage;
+
+@ExtendWith(ApplicationExtension.class)
+class JavaFxTest {
+
+    private Button button;
+
+    /**
+     * Will be called with {@code @Before} semantics, i. e. before each test method.
+     *
+     * @param stage - Will be injected by the test runner.
+     */
+    @Start
+    private void start(Stage stage) {
+        button = new Button("click me!");
+        button.setId("myButton");
+        button.setOnAction(actionEvent -> button.setText("clicked!"));
+        stage.setScene(new Scene(new StackPane(button), 100, 100));
+        stage.show();
+    }
+
+    /**
+     * @param robot - Will be injected by the test runner.
+     */
+    @Test
+    void buttonShouldHaveText(FxRobot robot) {
+        Assertions.assertThat(button).hasText("click me!");
+        // or (lookup by css id):
+        Assertions.assertThat(robot.lookup("#myButton").queryAs(Button.class)).hasText("click me!");
+        // or (lookup by css class):
+        Assertions.assertThat(robot.lookup(".button").queryAs(Button.class)).hasText("click me!");
+        // or (query specific type):
+        Assertions.assertThat(robot.lookup(".button").queryButton()).hasText("click me!");
+    }
+
+    /**
+     * @param robot - Will be injected by the test runner.
+     */
+    @Test
+    void textChangesIfButtonClicked(FxRobot robot) {
+        // when:
+        robot.clickOn(".button");
+
+        // then:
+        Assertions.assertThat(button).hasText("clicked!");
+        // or (lookup by css id):
+        Assertions.assertThat(robot.lookup("#myButton").queryAs(Button.class)).hasText("clicked!");
+        // or (lookup by css class):
+        Assertions.assertThat(robot.lookup(".button").queryAs(Button.class)).hasText("clicked!");
+        // or (query specific type)
+        Assertions.assertThat(robot.lookup(".button").queryButton()).hasText("clicked!");
+    }
+}