Understanding Emma Coverage for Enum Types in Java

What are the best practices for achieving Emma code coverage on Enum types in Java?

public enum Day {
    SUNDAY,
    MONDAY,
    TUESDAY,
    WEDNESDAY,
    THURSDAY,
    FRIDAY,
    SATURDAY;
}

Measuring code coverage using the Emma framework for Java can be challenging, especially when it comes to Enum types. This guide provides insight into how you can effectively measure this coverage and the factors to consider during the process.

import org.junit.Test;
import static org.junit.Assert.*;

public class DayTest {
    @Test
    public void testEnumValues() {
        for (Day day : Day.values()) {
            assertNotNull(day);
            // Further assertions for each Enum value can be added here.
        }
    }
}

Causes

• Enum types may not be instantiated in the traditional sense, leading to inaccurate coverage metrics.
• Certain testing frameworks or setups do not adequately invoke all Enum values during testing.

Solutions

• Ensure that unit tests cover all Enum constants by invoking each explicitly during test cases.
• Use mock objects where appropriate to test the behavior of Enum constants in different scenarios.
• Review your testing strategy to confirm that all paths through Enum logic are exercised.

Mistake: Not testing all Enum values leading to incomplete coverage reports.

Solution: Implement a comprehensive testing method to ensure each value is invoked at least once.

Mistake: Assuming that simply referencing the Enum type in tests counts as coverage.

Solution: Explicitly invoke methods or access properties of each Enum value during unit tests.