@EnumSource for enum values in JUnit - Test Execution Trace

Test Overview

This test uses JUnit's @EnumSource to run the same test method for each value of an enum. It verifies that the enum values are correctly passed and processed in the test.

Test Code - JUnit 5

JUnit

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.EnumSource;
import static org.junit.jupiter.api.Assertions.*;

public class TrafficLightTest {

    enum TrafficLight {
        RED, YELLOW, GREEN
    }

    @ParameterizedTest
    @EnumSource(TrafficLight.class)
    void testTrafficLightEnum(TrafficLight light) {
        assertNotNull(light);
        assertTrue(light == TrafficLight.RED || light == TrafficLight.YELLOW || light == TrafficLight.GREEN);
    }
}

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test runner starts and identifies the parameterized test with @EnumSource for TrafficLight enum	JUnit test environment ready to run tests	-	PASS
2	Test method 'testTrafficLightEnum' runs with parameter TrafficLight.RED	Test method executing with parameter RED	assertNotNull(RED) and assertTrue(RED is one of RED, YELLOW, GREEN)	PASS
3	Test method 'testTrafficLightEnum' runs with parameter TrafficLight.YELLOW	Test method executing with parameter YELLOW	assertNotNull(YELLOW) and assertTrue(YELLOW is one of RED, YELLOW, GREEN)	PASS
4	Test method 'testTrafficLightEnum' runs with parameter TrafficLight.GREEN	Test method executing with parameter GREEN	assertNotNull(GREEN) and assertTrue(GREEN is one of RED, YELLOW, GREEN)	PASS
5	All enum values tested, test suite completes	All parameterized tests passed	-	PASS

Failure Scenario

Failing Condition: If the enum value passed to the test method is null or not one of the expected enum constants

Execution Trace Quiz - 3 Questions

What does @EnumSource(TrafficLight.class) do in this test?

A Runs the test method only once with the first enum value

B Runs the test method once for each value in the TrafficLight enum

C Skips the test method for all enum values

D Runs the test method with random enum values

Key Result

Using @EnumSource in JUnit allows easy testing of all enum values without writing separate tests, ensuring full coverage of enum-related logic.