如何使用JUnit單元測試JavaFX控制器

Question

什麼是初始化JavaFX運行時的正確方法，以便您可以使用併發功能和Platform.runLater(Runnable)進行單元測試（使用JUnit）控制器？

從@BeforeClass方法調用Application.launch(...)會導致死鎖。如果Application.launch(...)不那麼叫拋出以下錯誤：

java.lang.IllegalStateException: Toolkit not initialized 
    at com.sun.javafx.application.PlatformImpl.runLater(PlatformImpl.java:121) 
    at com.sun.javafx.application.PlatformImpl.runLater(PlatformImpl.java:116) 
    at javafx.application.Platform.runLater(Platform.java:52) 
    at javafx.concurrent.Task.runLater(Task.java:1042) 
    at javafx.concurrent.Task.updateMessage(Task.java:987) 
    at com.xyz.AudioSegmentExtractor.call(AudioSegmentExtractor.java:64) 
    at com.xyz.CompletionControllerTest.setUp(CompletionControllerTest.java:69) 
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) 
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) 
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) 
    at java.lang.reflect.Method.invoke(Method.java:601) 
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44) 
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15) 
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41) 
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:76) 
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50) 
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193) 
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52) 
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191) 
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42) 
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184) 
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236) 
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50) 
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) 
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467) 
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683) 
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390) 
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197) 

---

跟帖：這是我通過@SergeyGrinev基於推薦一直使用的主題。

... // Inside test class 

public static class AsNonApp extends Application { 
    @Override 
    public void start(Stage primaryStage) throws Exception { 
     // noop 
    } 
} 

@BeforeClass 
public static void initJFX() { 
    Thread t = new Thread("JavaFX Init Thread") { 
     public void run() { 
      Application.launch(AsNonApp.class, new String[0]); 
     } 
    }; 
    t.setDaemon(true); 
    t.start(); 
} 
... // controller tests follow... 

Answer 1

調用從@BeforeClasslaunch()是一個正確的做法。請注意0​​不會將控制權返回給調用代碼。所以你必須把它包裝到new Thread(...).start()。

Answer 2

我發現這個工作，但只有在啓動JavaFX應用程序線程後添加Thread.sleep（500）之後。大概需要一段時間才能使FX環境準備就緒（我的MacBook Pro視網膜上大約需要200毫秒）

@BeforeClass 
public static void setUpClass() throws InterruptedException { 
    // Initialise Java FX 

    System.out.printf("About to launch FX App\n"); 
    Thread t = new Thread("JavaFX Init Thread") { 
     public void run() { 
      Application.launch(AsNonApp.class, new String[0]); 
     } 
    }; 
    t.setDaemon(true); 
    t.start(); 
    System.out.printf("FX App thread started\n"); 
    Thread.sleep(500); 
}