java – 如何使用多个ArgumentCaptor参数

2023年3月3日 549次阅读

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<String> argName = ArgumentCaptor.forClass(String.class);
ArgumentCaptor<List> 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<String> 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<String> 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<String> fileNameCaptor;

    @Captor
    private ArgumentCaptor<List<String>> 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.

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