1. JUnit dependencies

• Option with less dependencies:

      <dependency>
          <groupId>org.junit.jupiter</groupId>
          <artifactId>junit-jupiter-api</artifactId>
          <version>5.11.0</version>
          <scope>test</scope>
      </dependency>
      <dependency>
          <groupId>org.junit.jupiter</groupId>
          <artifactId>junit-jupiter-engine</artifactId>
          <version>5.11.0</version>
          <scope>test</scope>
      </dependency>
      <dependency>
          <groupId>org.junit.jupiter</groupId>
          <artifactId>junit-jupiter-params</artifactId>
          <version>5.11.0</version>
          <scope>test</scope>
      </dependency>

• Full option:

    <dependency>
        <groupId>org.junit.jupiter</groupId>
        <artifactId>junit-jupiter</artifactId>
        <version>5.11.0</version>
        <scope>test</scope>
    </dependency>

2. Mockito

• What is Mockito?
  • Mockito is an open source testing framework created for Java.
  • It allows us to easily create "test doubles" objects in unit tests.

2.1. Test Double

• What is Test Double?
  • Test doubles are stand-ins for the real components of your software under test.
• They mimic the behavior of these components, allowing you to test the code in isolation without relying on any dependencies.
• Different testing types require varying functioning features of the software.
• There might be cases where a certain test run may need the function to return a numeric value.

2.2. Types of Test Doubles

• Choosing the right test double for such test scenarios is critical.
• This is the list of different types of test doubles available:

  Types	Description
  Fake	Simplified implementation Basic functionality
  Stub	Predetermined responses Mimics behavior
  Mock	Behavior verification Method call tracking
  Dummies	Placeholder objects No functionality
  Spies	Interaction monitoring Observes behavior

2.3. Mockito dependencies

    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-junit-jupiter</artifactId>
        <version>5.14.2</version>
        <scope>test</scope>
    </dependency>

2.4. Annotations

• @ExtendWith(MockitoExtension.class) - To the test class and annotating mocked fields with @Mock.

  • @RunWith(MockitoJUnitRunner.class) - JUnit 4

• @InjectMocks - Creates an instance of the class and injects the mocks that are created with the @Mock (or @Spy) annotations into this instance.

• @Mock - Creates a mock implementation for the classes we need.

• Example

    @ExtendWith(MockitoExtension.class)
    public class ExampleClassTest {
        @InjectMocks
        MyServiceToBeTested myServiceToBeTested;
  
        @Mock
        MyDependency myDependency;
    }

  

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