如何存根 Mockito 测试类的私有方法 [英] How to stub private methods of class under test by Mockito

问题描述

假设我们有一个名为 SomeClass 的 Java 类

Say we have java class called SomeClass

public class SomeClass {

    private boolean isMethod() {

        return false;
    }

    public void sendRequest(String json, String text) {

        int messageId;

        if (isMethod()) {
            messageId = getMessageId(json);
            sendMessage(messageId, text);
        } else {
            throw new IllegalArgumentException();
        }
    }

    private void sendMessage(int messageId, String text) {

    }

    private int getMessageId(String text) {

        Pattern p = Pattern.compile("messageId=(\\d+)&");
        Matcher m = p.matcher(text);

        if (m.find()) {
            return Integer.valueOf(m.group(1));
        }
        return 0;
    }
}

不要在意方法的名字，它们都是可选的.

Don't pay attention to methods' name, they're all optional.

• 我想单独测试 sendRequest(String json, String text) 方法.
• 我想存根方法 isMethod() 和 getMessageId(json)，并验证 sendMessage(messageId, text) 方法被调用.
• 我需要确保 getMessageId(json) 返回 25 并且 isMethod() 无论给出哪个参数值都返回 true.

• I want to test sendRequest(String json, String text) method in isolation.
• I want to stub methods isMethod() and getMessageId(json), and verify that sendMessage(messageId, text) method is called.
• I need to be sure that getMessageId(json) returns 25 and that isMethod() returns true no matter which argument value given.

推荐答案

这可以通过 PowerMockito 框架来实现.

This could be achieved by PowerMockito framework.

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(SomeClass.class)
public class SomeClassTest {

    private SomeClass someInstance;

    @Before
    public void setUp() throws Exception {

        someInstance = PowerMockito.spy(new SomeClass());
    }

    @Test
    public void sendRequest() throws Exception {

        String json = "JSON";
        String text = "Some text";
        int messageId = 1;

        PowerMockito.doReturn(true).when(someInstance, "isMethod");
        PowerMockito.doReturn(messageId).when(someInstance, "getMessageId", json);

        someInstance.sendRequest(json, text);

        PowerMockito.verifyPrivate(someInstance).invoke("isMethod");
        PowerMockito.verifyPrivate(someInstance).invoke("getMessageId", json);
        PowerMockito.verifyPrivate(someInstance).invoke("sendMessage", messageId, text);
    }

}

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