목 상호 작용 검증
목 객체가 예상한 인수와 특정 호출 횟수로 호출되었는지 검증하는 방법을 배웁니다.
목 상호 작용 검증은(는) CoddyKit의 무료 Testing Mastery: JUnit, Mockito & Integration Tests 강의입니다. 이것은 4개 중 3번째 강의입니다. 아래에서 전체 강의를 무료로 읽을 수 있으며, 내장 코드 에디터와 24/7 AI 튜터와 함께 브라우저에서 직접 실습할 수 있습니다. 이 강의는 Testing Mastery: JUnit, Mockito & Integration Tests 학습 경로의 일부이며, 진행 상황이 웹과 CoddyKit 앱에 동기화됩니다. Testing Mastery: JUnit, Mockito & Integration Tests 강의에는 총 4개의 강의가 포함되어 있습니다.
이 강의의 일부는 아직 번역되지 않았으며 영어로 표시됩니다.
Intro to Mockito Verification
Welcome to verifying mock interactions! After learning to create mocks, the next crucial step is to confirm how they were used.
Verification in Mockito means checking if specific methods on your mock objects were called during a test.
Why Verify Interactions?
When testing a class, you often want to ensure it correctly interacts with its dependencies.
- Collaboration Check: Did the object under test call the right methods on its collaborators?
- Behavior Confirmation: Did it pass the correct arguments to those methods?
- Interaction Count: Was a method called once, multiple times, or not at all?
Verification answers these questions, ensuring your code behaves as expected.
The Basic `verify()` Method
The simplest way to verify an interaction is using Mockito.verify(). It checks if a method was called exactly once.
You write verify(mockObject).methodCall(); after the code under test has run. If the method wasn't called, or was called more than once, Mockito will throw an error.
Code: Basic `verify()` in Action
Try this runnable example. We'll simulate a test by creating a mock and calling a method on it. Then, we verify the interaction.
In a real JUnit test, a failed verification would make the test fail.
import static org.mockito.Mockito.*;
interface MyService {
void doSomething();
}
class MyProcessor {
private MyService service;
public MyProcessor(MyService service) {
this.service = service;
}
public void execute() {
service.doSomething();
}
}
public class Main {
public static void main(String[] args) {
MyService mockService = mock(MyService.class);
MyProcessor processor = new MyProcessor(mockService);
System.out.println("Calling execute...");
processor.execute(); // This calls mockService.doSomething()
try {
// Verify doSomething() was called exactly once
verify(mockService).doSomething();
System.out.println("\nVerification successful: doSomething() called once.");
} catch (Throwable e) {
System.out.println("\nVerification failed: " + e.getMessage());
}
System.out.println("Program finished.");
}
}Verifying Specific Arguments with `eq()`
Often, you need to check not just if a method was called, but with what arguments.
Use eq(value) to match an exact argument value. For example, verify(mock).someMethod(eq("hello"), eq(123)); ensures the method was called with "hello" and 123.
You can also use generic matchers like anyString() or anyInt() if you don't care about a specific argument's value.
Code: `verify()` with `eq()`
Here, we verify that a message was sent with specific content and priority. Notice how eq() helps us be precise.
import static org.mockito.Mockito.*;
interface DataSender {
void send(String message, int priority);
}
class MessageProcessor {
private DataSender sender;
public MessageProcessor(DataSender sender) {
this.sender = sender;
}
public void processAndSend(String data) {
sender.send(data.toUpperCase(), 1);
}
}
public class Main {
public static void main(String[] args) {
DataSender mockSender = mock(DataSender.class);
MessageProcessor processor = new MessageProcessor(mockSender);
System.out.println("Processing 'hello' message...");
processor.processAndSend("hello");
try {
// Verify send() was called with "HELLO" and 1
verify(mockSender).send(eq("HELLO"), eq(1));
System.out.println("\nVerification successful: Correct arguments received.");
} catch (Throwable e) {
System.out.println("\nVerification failed: " + e.getMessage());
}
// The following commented block shows a failing verification
// try {
// verify(mockSender).send(eq("hello"), eq(1)); // "hello" (lowercase) is wrong
// System.out.println("This should not be printed.");
// } catch (Throwable e) {
// System.out.println("Expected failure for wrong arguments: " + e.getMessage());
// }
System.out.println("Program finished.");
}
}Verifying Call Counts: `times()` & `never()`
Sometimes, you need to verify how many times a method was called:
verify(mock, times(N)).method();: Called exactly N times.verify(mock, never()).method();: Never called (same astimes(0)).
These are powerful for ensuring loops, conditions, or error handling work correctly.
Code: `times()` and `never()`
This example processes multiple events and logs an error. We'll verify the exact number of times each type of log was made.
import static org.mockito.Mockito.*;
interface EventLogger {
void log(String event);
}
class EventProcessor {
private EventLogger logger;
public EventProcessor(EventLogger logger) {
this.logger = logger;
}
public void processEvents(int count) {
for (int i = 0; i < count; i++) {
logger.log("Event " + (i + 1));
}
}
public void logError(String error) {
logger.log("ERROR: " + error);
}
}
public class Main {
public static void main(String[] args) {
EventLogger mockLogger = mock(EventLogger.class);
EventProcessor processor = new EventProcessor(mockLogger);
System.out.println("Processing 3 events and logging an error...");
processor.processEvents(3);
processor.logError("Failed to connect");
try {
// Verify log() was called 3 times with arguments starting with "Event "
verify(mockLogger, times(3)).log(startsWith("Event "));
System.out.println("\nVerification successful: 'Event' logged 3 times.");
// Verify log() was called once with the exact error message
verify(mockLogger, times(1)).log(eq("ERROR: Failed to connect"));
System.out.println("Verification successful: Error logged once.");
// Verify log() was never called with arguments starting with "WARNING"
verify(mockLogger, never()).log(startsWith("WARNING"));
System.out.println("Verification successful: 'WARNING' never logged.");
} catch (Throwable e) {
System.out.println("\nVerification failed: " + e.getMessage());
}
System.out.println("Program finished.");
}
}Flexible Call Counts: `atLeast()`, `atMost()`
Sometimes an exact count isn't necessary, but a range is important:
verify(mock, atLeast(N)).method();: Called N or more times.verify(mock, atMost(N)).method();: Called N or fewer times.
There are also convenient shortcuts: atLeastOnce() and atMostOnce() for clarity.
Verify Interactions Check
Which of the following are valid ways to verify method calls using Mockito?
Recap: Mastering Verification
You've learned how to verify mock interactions in Mockito!
verify(mock).method();checks for a single call.- Use
eq()for exact argument matching or generic matchers likeanyString(). - Control call counts with
times(N),never(),atLeast(N), andatMost(N).
Mastering verification is key to writing robust, reliable unit tests that confirm precise object collaboration.
자주 묻는 질문
“목 상호 작용 검증” 강의는 무료인가요?
네 — “목 상호 작용 검증” 전체 내용을 이 웹사이트에서 무료로 읽을 수 있습니다. 인터랙티브하게 실습하려면(내장 코드 에디터와 24/7 AI 튜터), CoddyKit PRO로 업그레이드하면 Testing Mastery: JUnit, Mockito & Integration Tests 강의 전체를 잠금 해제할 수 있습니다. Testing Mastery: JUnit, Mockito & Integration Tests 강의에는 총 4개의 강의가 포함되어 있습니다.
“목 상호 작용 검증”에서 뭘 배우나요?
목 객체가 예상한 인수와 특정 호출 횟수로 호출되었는지 검증하는 방법을 배웁니다. 브라우저에서 직접 실행하는 실습 코드로 Testing Mastery: JUnit, Mockito & Integration Tests을(를) 배우며, 24/7 AI 튜터가 강의를 진행하면서 질문에 답변해줍니다.
Testing Mastery: JUnit, Mockito & Integration Tests을(를) 시작하는 데 경험이 필요한가요?
사전 경험은 필요하지 않습니다. CoddyKit의 Testing Mastery: JUnit, Mockito & Integration Tests은(는) 초급자부터 고급 학습자까지를 위해 구성되어 있으므로, 여기서 시작하거나 처음부터 시작할 수 있으며 자신의 속도대로 진행할 수 있습니다. 이것은 4개 중 3번째 강의입니다.
“목 상호 작용 검증” 강의는 얼마나 걸리나요?
대부분의 CoddyKit 강의는 약 5~10분이 소요됩니다. 각 강의는 간결하고 인터랙티브하여 꾸준한 진행이 가능하며, 웹과 앱에서 중단한 부분부터 바로 시작할 수 있습니다.
이 Testing Mastery: JUnit, Mockito & Integration Tests 강의에서 코드를 작성하고 실행할 수 있나요?
네. 모든 Testing Mastery: JUnit, Mockito & Integration Tests 강의에는 내장 코드 에디터가 포함되어 있으므로, 브라우저에서 바로 실제 코드를 작성하고 실행한 후 즉시 AI 피드백을 받을 수 있습니다 — 로컬 설정이 필요 없습니다.