How to Exclude a Method from JaCoCo Code Coverage Reports in Java

How can I add an annotation to exclude a method from a JaCoCo code coverage report in Java?

public class Something {
    @ExcludeFromCodeCoverage
    public void someMethod() {}
}

Using JaCoCo for code coverage in Java projects is a common practice. Sometimes, you may want to exclude certain methods or classes from the coverage reports, especially test utility methods or heavily mocked methods. This can be achieved by using a custom exclusion annotation, configuring JaCoCo in Gradle, and leveraging the `@ExcludeFromCodeCoverage` annotation.

// Custom annotation definition
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface ExcludeFromCodeCoverage {}

// Example usage in your Java class
public class Something {
    @ExcludeFromCodeCoverage
    public void someMethod() {}
}

Causes

• You want to keep your code coverage report focused on meaningful tests.
• Certain methods are not relevant for coverage, such as utility methods or those that do not contain logic.

Solutions

• Create a custom annotation to mark methods for exclusion.
• Use JaCoCo's `Excludes` option in your JaCoCo configuration to specify exclusion patterns.

Mistake: Not configuring JaCoCo to recognize custom annotations.

Solution: Make sure to include your custom annotation in the JaCoCo configuration to ensure it is recognized as an exclusion.

Mistake: Excluding too many methods, reducing test effectiveness.

Solution: Only mark methods that do not contribute to the logic you want covered.