尝试使用PowerMock模拟静态系统类时出现VerifyError

Question

我正试图模拟JOptionPane静态方法，但却被困在Java上。lang.VerifyError。所有版本都是最新的，因为我刚刚下载了Mockito的PowerMock及其所有依赖项。

我不能使用前面问题的答案来包装类和包装器的子类-这在我们的应用程序中无处不在。目前我已经在PowerMock上投入了相当多的时间，我不想从fest开始。

有没有办法解决这个错误？我在说明中尝试了“模拟静态方法”和“模拟系统类”。我不能再往前走了，因为我所做的只是@RunWith（PowerMockRunner.class）和@PrepareForTest（My.class）。

我发现，只要引用扩展JPanel的类，就可以将此问题简化为一个问题。下面是创建问题的最低测试（我在Boffo和JPanel上得到了与PrepareForTest相同的异常）：

import javax.swing.JPanel;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
//@PrepareForTest(JPanel.class)
@PrepareForTest(TestCase.Boffo.class)
public class TestCase {

    @SuppressWarnings("serial")
    public static class Boffo extends JPanel {}

    @Test
    public void test() throws Exception {
        new Boffo();
    }
}

这是我尝试运行测试时得到的异常：

java.lang.VerifyError: (class: javax/swing/plaf/metal/MetalLookAndFeel, method: getLayoutStyle signature: ()Ljavax/swing/LayoutStyle;) Wrong return type in function
    at javax.swing.UIManager.setLookAndFeel(Unknown Source)
    at javax.swing.UIManager.initializeDefaultLAF(Unknown Source)
    at javax.swing.UIManager.initialize(Unknown Source)
    at javax.swing.UIManager.maybeInitialize(Unknown Source)
    at javax.swing.UIManager.getUI(Unknown Source)
    at javax.swing.JPanel.updateUI(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)
    at javax.swing.JPanel.<init>(Unknown Source)
    at com.package.TestCase$Boffo.<init>(TestCase.java:17)
    at com.package.TestCase.test(TestCase.java:21)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:66)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:312)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:86)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:94)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:296)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:284)
    at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:84)
    at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:49)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:209)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:148)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:122)
    at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:34)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:44)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:120)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:102)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:53)
    at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:42)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
    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)

Answer 1

我不知道为什么它会抛出VerifyError，但可以通过在实例化类之前预先设置一个伪LookAndFill来克服它。

public static class FakeLookAndFill extends BasicLookAndFeel {
    @Override
    public String getName() {
        return "FakeLookAndFill";
    }

    @Override
    public String getID() {
        return "FakeLookAndFill";
    }

    @Override
    public String getDescription() {
        return "FakeLookAndFill";
    }

    @Override
    public boolean isNativeLookAndFeel() {
        return false;
    }

    @Override
    public boolean isSupportedLookAndFeel() {
        //note it returns true
        return true;
    }
}

@Before
public void setUp() throws Exception {
    UIManager.setLookAndFeel(new FakeLookAndFill());
}

Answer 2

我的一位同事今天发现了一个巧妙的解决方法：只需将注释添加到测试类中，PowerMockIgnore（“javax.swing.*），PowerMock就会将有问题的类延迟加载到系统类加载器。

编辑：只要重新阅读这个问题，既然你试图嘲笑JOptionPane本身，我不确定这是否会有帮助，但也许你可以尝试排除模式。