How to block private methods of a class controlled by Mockito

Question

Say we have a 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;
    }
}

Do not pay attention to the name of the method, all of them are optional.

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

Answer 1

This can be achieved using the PowerMockito environment.

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);
    }

}

Answer 2

, , , , , , implementation public contract of a class. , . , , . , implementation contract.

, ,

Answer 3

, Maven,

<!-- https://mvnrepository.com/artifact/org.powermock/powermock-module-junit4 -->
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-module-junit4</artifactId>
    <version>2.0.0</version>
    <scope>test</scope>
</dependency>

<!-- https://mvnrepository.com/artifact/org.powermock/powermock-api-mockito2 -->
<dependency>
    <groupId>org.powermock</groupId>
    <artifactId>powermock-api-mockito2</artifactId>
    <version>2.0.0</version>
    <scope>test</scope>
</dependency>