Object Mother pattern in JUnit - Test Execution Trace

Test Overview

This test uses the Object Mother pattern to create a ready-to-use User object. It verifies that the User object created by the Object Mother has the expected default values.

Test Code - JUnit 5

JUnit

import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;

class User {
    private String name;
    private int age;

    public User(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }
}

class UserObjectMother {
    public static User createDefaultUser() {
        return new User("Alice", 30);
    }
}

public class UserTest {

    @Test
    void testDefaultUserCreation() {
        User user = UserObjectMother.createDefaultUser();
        assertEquals("Alice", user.getName());
        assertEquals(30, user.getAge());
    }
}

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts	JUnit test runner initializes the test class UserTest	-	PASS
2	Calls UserObjectMother.createDefaultUser() to get a User object	User object with name 'Alice' and age 30 is created	-	PASS
3	Calls user.getName() and asserts it equals 'Alice'	User object is accessible with name 'Alice'	assertEquals("Alice", user.getName())	PASS
4	Calls user.getAge() and asserts it equals 30	User object is accessible with age 30	assertEquals(30, user.getAge())	PASS
5	Test completes successfully	All assertions passed	-	PASS

Failure Scenario

Failing Condition: UserObjectMother.createDefaultUser() returns a User with incorrect name or age

Execution Trace Quiz - 3 Questions

What does the Object Mother pattern help with in this test?

A Automatically generating test reports

B Running tests faster by skipping assertions

C Creating ready-to-use test objects with default values

D Mocking external services

Key Result

Using the Object Mother pattern helps create consistent test objects easily, reducing duplication and making tests clearer.