Mockito BDDMockito

1. Overview

Mockito's BDDMockito class provides a BDD-style syntax for writing tests. BDD, or Behavior-Driven Development, is an agile software development process that encourages collaboration between developers, QA, and non-technical participants in a software project. BDDMockito provides methods that closely align with BDD terminology, making the tests more readable and closer to natural language. In this tutorial, we'll explore the key methods provided by BDDMockito.

2. Development Steps

1. Set up a new Maven project.

2. Add the required Mockito and JUnit 5 dependencies.

3. Design a simple class, Calculator, for demonstration.

4. Design a BDD-style test for the Calculator using BDDMockito.

5. Run the tests and analyze the results.

6. Reflect on the benefits of BDD-style testing with Mockito.

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

// A simple Calculator class for demonstration
class Calculator {
    double add(double a, double b) {
        return a + b;
    }
}
// BDD-style test class for the Calculator
import org.junit.jupiter.api.Test;
import static org.mockito.BDDMockito.*;
public class CalculatorBDDTest {
    @Test
    public void testCalculatorAdd() {
        // Given: Setup the test scenario
        Calculator mockCalculator = mock(Calculator.class);
        given(mockCalculator.add(10.0, 20.0)).willReturn(30.0);
        // When: Execute the actual behavior
        double result = mockCalculator.add(10.0, 20.0);
        // Then: Verify the expected outcome
        then(mockCalculator).should(times(1)).add(10.0, 20.0);
        System.out.println("Result: " + result);
    }
}

Output:

Result: 30.0

Code Explanation:

1. A simple Calculator class is defined with an add method.

2. The test class CalculatorBDDTest is designed to test the Calculator class in a BDD style using BDDMockito.

3. BDDMockito provides a given method, which sets up the scenario by defining the mocked behavior. Here, we mock the add method's behavior.

4. The actual behavior or action to test is represented by the "When" section. We call the mocked add method and store its result.

5. BDDMockito's then method is used to verify the outcomes. We ensure the mocked method was called the expected number of times.

6. The printed result confirms our mocked behavior executed correctly.

5. Conclusion

BDDMockito offers a structured and easily readable way to design Mockito tests in line with BDD principles. By focusing on the "Given-When-Then" structure, tests become clearer, aligning the technical implementation with business requirements. As a result, collaboration between technical and non-technical stakeholders improves, leading to better software quality and more comprehensive testing.

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()