带有String[].class参数的Powermock ProcessBuilder构造函数

Question

当我尝试对ProcessBuilder构造函数进行powermock时，如果参数是ArrayList，它会成功，但当参数是String数组时，它会失败。

要测试的类别是：

package test;
import java.util.ArrayList;
public class MockProcessBuilder {
    public void instance1() throws Exception {
        String chmodCmd[] = { "/bin/chmod", "755", "/path/to/dest" + "/" + "file.txt" };
        // constructor with String[].class
        ProcessBuilder pb = new ProcessBuilder(chmodCmd);
        pb.redirectErrorStream(true);
        Process proc = pb.start();
        proc.waitFor();
    }
    public void instance2() throws Exception {
        ArrayList<String> cmdArrayList = new ArrayList<String>();
        cmdArrayList.add("/bin/execScript");
        cmdArrayList.add("exec");
        cmdArrayList.add("ls -altr");
        // constructor with ArrayList.class             
        ProcessBuilder pb = new ProcessBuilder(cmdArrayList);
        pb.redirectErrorStream(true);
        Process proc = pb.start();
        proc.waitFor();
    }
}

测试类别为：

package test;
import static org.mockito.Matchers.isA;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import java.util.ArrayList;
import java.util.List;
@RunWith(PowerMockRunner.class)
@PrepareForTest({MockProcessBuilder.class, ProcessBuilder.class})
public class MockProcessBuilderTest {
    @Mock ProcessBuilder pb;
    @Mock Process proc;
    // fail. NullPointerException
    @Test
    public void testInstance1() throws Exception {
        PowerMockito.whenNew(ProcessBuilder.class).withParameterTypes(String[].class).withArguments(isA(String[].class)).thenReturn(pb);
        Mockito.when(pb.start()).thenReturn(proc);
        MockProcessBuilder mpb = new MockProcessBuilder();
        mpb.instance1();
    }
    // success
    @Test
    public void testInstance2() throws Exception {
        PowerMockito.whenNew(ProcessBuilder.class).withParameterTypes(List.class).withArguments(isA(ArrayList.class)).thenReturn(pb);
        Mockito.when(pb.start()).thenReturn(proc);
        MockProcessBuilder mpb = new MockProcessBuilder();
        mpb.instance2();
    }
}

第一个测试用例失败并出现错误：

java.lang.NullPointerException

有人知道如何模拟第一个构造函数吗？

感谢

编辑完整跟踪：

java.lang.NullPointerException
at test.MockProcessBuilder.instance1(MockProcessBuilder.java:14)
at test.MockProcessBuilderTest.testInstance1(MockProcessBuilderTest.java:32)
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:616)
at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:310)
at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:88)
at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:96)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:294)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:127)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTest(PowerMockJUnit47RunnerDelegateImpl.java:82)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:282)
at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:86)
at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:49)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:207)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:146)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:120)
at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:33)
at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:45)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:118)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:101)
at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:53)
at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:53)
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)

Answer 1

testInstance1（）测试失败，因为参数匹配器isA(String[].class)与您提供的String varargs参数不匹配。要使测试通过，请替换testInstance1（）行

PowerMockito.whenNew(ProcessBuilder.class).withParameterTypes(String[].class).
             withArguments(isA(String[].class)).thenReturn(pb);

带有

PowerMockito.whenNew(ProcessBuilder.class).withParameterTypes(String[].class).
             withArguments(anyVararg()).thenReturn(pb);

Powermock正在拦截对ProcessBuilder varargs构造函数的调用，因为PowerMockito.whenNew(ProcessBuilder.class).withParameterTypes(String[].class)与varargs构造器匹配。但是，由于withArguments(isA(String[].class))不匹配，thenReturn被忽略，Powermock只返回null而不是pb mock。

另请参阅如何在Mockito 中正确匹配varargs