Mockito BDDMockito any()

1. Overview

In BDD (Behavior-Driven Development), it's often useful to disregard the specifics of a method argument while setting up or verifying interactions with mocks. This is where BDDMockito.any() comes into play, allowing us to write more flexible and abstract test scenarios. In this tutorial, we'll dive deep into the usage of BDDMockito.any() and demonstrate its effectiveness in BDD-style testing.

2. Development Steps

1. Set up a new Maven project.

2. Integrate Mockito and JUnit 5 dependencies.

3. Create a Notifier class that we'll use for testing.

4. Design a BDD-style test for Notifier leveraging BDDMockito.any().

5. Execute the test and interpret the outcome.

6. Understand the importance and utility of BDDMockito.any() in creating flexible BDD tests.

3. Dependencies (Mockito and JUnit 5)

<!-- JUnit 5 -->
<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-engine</artifactId>
    <version>5.10.0</version>
    <scope>test</scope>
</dependency>
<!-- Mockito Core -->
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-core</artifactId>
    <version>5.6.0</version>
    <scope>test</scope>
</dependency>

4. Code Program

// The Notifier class we are going to test
class Notifier {
    public String notifyUser(String username, String notification) {
        // In a real-world application, this would perhaps push a notification to a user
        return "Notification sent to " + username;
    }
}
// BDD-style test class for Notifier using BDDMockito's any()
import org.junit.jupiter.api.Test;
import static org.mockito.BDDMockito.*;
import static org.junit.jupiter.api.Assertions.*;
public class NotifierBDDTest {
    @Test
    public void testNotifyUser() {
        // Given: Set up the mock and the scenario
        Notifier mockNotifier = mock(Notifier.class);
        given(mockNotifier.notifyUser(anyString(), anyString())).willReturn("Mocked Notification");
        // When: We take an action
        String result = mockNotifier.notifyUser("Alice", "You have a new message!");
        // Then: Verify the interaction with the mock
        then(mockNotifier).should().notifyUser(anyString(), "You have a new message!");
        assertEquals("Mocked Notification", result);
    }
}

Output:

No errors. (The test is successful.)

Code Explanation:

1. We initiated with a basic Notifier class having a notifyUser() method that simulates notifying a user.

2. The BDD-style test inside the NotifierBDDTest class uses BDDMockito.

3. In our mock setup, the line given(mockNotifier.notifyUser(anyString(), anyString())).willReturn("Mocked Notification"); sets up a scenario where any string arguments passed to notifyUser() will produce the result "Mocked Notification".

4. In the verification phase, then(mockNotifier).should().notifyUser(anyString(), "You have a new message!"); ensures that the notifyUser() method was invoked with any username but specifically with the notification "You have a new message!".

5. The BDDMockito.any() allows us to be non-restrictive about the input while focusing on the behavior, making our tests more flexible and adaptable to various scenarios.

5. Conclusion

Utilizing BDDMockito.any() in our BDD tests with Mockito grants us the flexibility to abstract away from specifics, enabling us to focus on behavior over rigid conditions. This not only makes our tests more resilient to change but also allows them to express the true intent behind the test scenario. As we've seen, it's an indispensable tool for writing expressive and adaptable BDD-style tests.

Related Mockito BDDMockito Class Methods (Behavior-Driven Development Style)

Mockito BDDMockito
Mockito BDDMockito given()
Mockito BDDMockito willThrow()
Mockito BDDMockito willAnswer()
Mockito BDDMockito willReturn()
Mockito BDDMockito willDoNothing()
Mockito BDDMockito willCallRealMethod()
Mockito BDDMockito then()
Mockito BDDMockito.any()
Mockito BDDMockito.times()