当我使用超过1个ArgumentCaptor参数时,我收到一个Nullpointer.可能有人知道出了什么问题？

@RunWith(PowerMockRunner.class)

@PrepareForTest(FileHelper.class)

public class MyTest {

...

@Before

public void setUp() throws Exception {

PowerMockito.mockStatic(FileHelper.class);

}

@Test

public void save() throws Exception {

ArgumentCaptor argName = ArgumentCaptor.forClass(String.class);

ArgumentCaptor argList = ArgumentCaptor.forClass(List.class);

PowerMockito.doNothing().when(FileHelper.class, "saveTextFile", argName.capture(),

argList.capture());

...

}

FileHelper类中的saveTextFile方法：

public static void saveTextFile(String filename, List data) {

...

}

如果我运行代码,我会得到以下异常：

java.lang.NullPointerException

at java.lang.Class.isAssignableFrom(Native Method)

at org.powermock.reflect.internal.WhiteboxImpl.checkIfParameterTypesAreSame(WhiteboxImpl.java:2432)

at org.powermock.reflect.internal.WhiteboxImpl.getMethods(WhiteboxImpl.java:1934)

at org.powermock.reflect.internal.WhiteboxImpl.getBestMethodCandidate(WhiteboxImpl.java:1025)

at org.powermock.reflect.internal.WhiteboxImpl.findMethodOrThrowException(WhiteboxImpl.java:948)

at org.powermock.reflect.internal.WhiteboxImpl.doInvokeMethod(WhiteboxImpl.java:882)

at org.powermock.reflect.internal.WhiteboxImpl.invokeMethod(WhiteboxImpl.java:859)

at org.powermock.reflect.Whitebox.invokeMethod(Whitebox.java:466)

at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.when(PowerMockitoStubberImpl.java:106)

如果我调用一个只有一个参数的方法,即list参数一切正常.

最佳答案 我想你可能想用“验证”代替什么时候.

你正在设定一个期望你的模拟“无所事事”.

调用正在测试的方法然后验证您预期会发生什么事情并不是更好吗？

例如,考虑这两个类……

HelperClass.java

public class HelperClass {

public static void nastyStaticCall(String filename, List data) {

System.out.println("REAL METHOD CALLED!!");

}

}

MyClass.java

import java.util.Arrays;

public class MyClass {

public void testMethod() {

HelperClass.nastyStaticCall("FILENAME", Arrays.asList("Data"));

}

}

如果我想测试“MyClass”,我会做这样的事……

import static org.fest.assertions.Assertions.assertThat;

import static org.powermock.api.mockito.PowerMockito.mockStatic;

import static org.powermock.api.mockito.PowerMockito.verifyStatic;

import java.util.List;

import org.junit.Before;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.mockito.ArgumentCaptor;

import org.mockito.Captor;

import org.mockito.MockitoAnnotations;

import org.powermock.core.classloader.annotations.PrepareForTest;

import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)

@PrepareForTest(HelperClass.class)

public class MyClassTest {

private MyClass classUnderTest;

@Captor

private ArgumentCaptor fileNameCaptor;

@Captor

private ArgumentCaptor> dataCaptor;

@Before

public void setup() {

MockitoAnnotations.initMocks(this);

mockStatic(HelperClass.class);

classUnderTest = new MyClass();

}

@Test

public void shouldMakeNastyStaticCall() {

classUnderTest.testMethod();

verifyStatic();

HelperClass.nastyStaticCall(fileNameCaptor.capture(), dataCaptor.capture());

assertThat(fileNameCaptor.getValue()).isEqualTo("FILENAME");

assertThat(dataCaptor.getValue()).containsOnly("Data");

}

}

如您所见,所有这些测试方法都会调用实际代码,然后验证是否使用正确的参数调用了辅助类.

如果您实际上期望静态方法调用返回一个值,该值将由您正在测试的方法的其余部分使用,那么您将需要使用“when”,但是当返回“void”时,您不需要做任何事.

一般来说,我个人避免在“when”条款中使用参数捕获者,并将其留在“验证”阶段.

希望这可以帮助.