PowerMock - Mocking static system class throws IllegalStateException

问题

I have the following code

public class A{    
    public void createFile() {
        File tempXmlFile = null;
        String extension = ".xml";
        String name = "someName";
        try {
            tempXmlFile = File.createTempFile(name, extension);

            if (tempXmlFile.exists()) {
                tempXmlFile.delete();
            }
        } catch (IOException e) {
            System.out.println(e.getStackTrace());
        }
    }
}


@RunWith(PowerMockRunner.class)
@PrepareForTest(A.class)
public class testA  extends TestCase{
    private A classUnderTest;

    @Override
    @Before
    public void setUp() {
        classUnderTest = PowerMock.createMock(A.class); //the class is more complex in my case and I have to mock it
    }

    public void testCreateFile() throws IOException{
        String extension = ".xml";
        String name = "someName";
        PowerMock.mockStatic(File.class);
        File tempFileMock = PowerMock.createMock(File.class);

        expect(File.createTempFile(name, extension)).andReturn(tempFileMock);
        expect(tempFileMock.exists()).andReturn(true);
        expect(tempFileMock.delete()).andReturn(true);

        replay(File.class, tempFileMock, classUnderTest);
        classUnderTest.createFile();
        verify(File.class, tempFileMock, classUnderTest);
    }
}

In the test class as I said the class under test must be mocked(I can't create a new object). When I run the test I get:

java.lang.IllegalStateException: no last call on a mock available
    at org.easymock.EasyMock.getControlForLastCall(EasyMock.java:174)
    at org.easymock.EasyMock.expect(EasyMock.java:156)
    at myPackage.testA.testCreateFile(testA.java:35)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:59)
    at org.junit.internal.runners.MethodRoadie.runTestMethod(MethodRoadie.java:98)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:79)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:87)
    at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:77)
    at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:42)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:163)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:120)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:113)
    at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:27)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:37)
    at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:111)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:87)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:44)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
    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)

I read the documentation here http://code.google.com/p/powermock/wiki/MockSystem but the test stil wont't work. Am I missing something?

Edit: I tested the previous code with a real A object (and removed it from replay)

  classUnderTest = new A();

but I still get the same exception.

回答1:

Try adding File.class to @PrepareForTest.

回答2:

try the org.powermock.reflect.internal.WhiteboxImpl.newInstance() method to create the object of the class and then call method directly. 1) this will suppress the constructor of the class 2) if your class contains static block then use suppressStaticInitilaizationFor to suppress that.

regards Anil Sharma