Unit tests in Laravel - Mini Project: Build & Apply

Unit Tests in Laravel

📖 Scenario: You are building a simple Laravel application that manages a list of tasks. Each task has a title and a status indicating if it is completed or not.To keep your code reliable, you want to write unit tests that check if your Task model behaves correctly.

🎯 Goal: Create a unit test class for the Task model in Laravel. You will write tests to check if a task can be created with a title and if the default status is false (not completed).

📋 What You'll Learn

Create a Task model with title and completed attributes

Create a unit test class called TaskTest

Write a test method test_task_can_be_created_with_title that asserts a task's title is set correctly

Write a test method test_task_default_completed_is_false that asserts the default completed status is false

💡 Why This Matters

🌍 Real World

Unit tests help ensure your Laravel models work correctly and prevent bugs when you change code.

💼 Career

Writing unit tests is a key skill for Laravel developers to maintain code quality and reliability.

1

Create the Task model with attributes

Create a Laravel model class called Task in app/Models/Task.php with public properties title and completed. Set completed default to false.

Laravel

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

// Define the Task model with title and completed properties

Hint

Define a class Task that extends Model. Add public properties title and completed with default false.

2

Create the TaskTest unit test class

Create a unit test class called TaskTest in tests/Unit/TaskTest.php that extends Tests\TestCase. Add the use statement for the App\Models\Task model.

Laravel

<?php

namespace Tests\Unit;

use Tests\TestCase;
use App\Models\Task;

// Define the TaskTest class

Hint

Create a class TaskTest that extends TestCase. Import the Task model with a use statement.

3

Write test for task creation with title

Inside the TaskTest class, write a public method called test_task_can_be_created_with_title. In it, create a new Task instance, set its title to 'Buy milk', and assert that the title property equals 'Buy milk' using $this->assertEquals().

Laravel

<?php

namespace Tests\Unit;

use Tests\TestCase;
use App\Models\Task;

class TaskTest extends TestCase
{
    // Write test_task_can_be_created_with_title method here
}

Hint

Define a public method test_task_can_be_created_with_title. Create a Task object, set title, and assert equality with assertEquals.

4

Write test for default completed status

Add a public method called test_task_default_completed_is_false inside TaskTest. Create a new Task instance and assert that its completed property is false using $this->assertFalse().

Laravel

title = 'Buy milk';
        $this->assertEquals('Buy milk', $task->title);
    }

    // Write test_task_default_completed_is_false method here
}

Hint

Define a public method test_task_default_completed_is_false. Create a Task object and assert completed is false with assertFalse.

Practice

1. What is the main purpose of unit tests in Laravel?

easy

A. To deploy the application to production

B. To create database migrations

C. To check small parts of code to catch errors early

D. To style the user interface

Solution

1. Step 1: Understand unit test purpose

   Unit tests focus on testing small, isolated parts of code to find bugs early.

2. Step 2: Compare options with unit test goals

   Only To check small parts of code to catch errors early describes this purpose; others relate to deployment, database, or UI.

3. Final Answer:

   To check small parts of code to catch errors early -> Option C

4. Quick Check:

   Unit tests = catch errors early [OK]

Hint: Unit tests check small code parts for bugs early [OK]

Common Mistakes:

• Confusing unit tests with deployment tasks
• Thinking unit tests handle UI styling
• Mixing unit tests with database migrations

2. Which of the following is the correct way to define a test method in a Laravel unit test class?

easy

A. function exampleTest() {}

B. public function testExample() {}

C. public test function example() {}

D. def test_example():

Solution

1. Step 1: Recall Laravel test method syntax

   Laravel test methods are public functions starting with 'test' or annotated with @test.

2. Step 2: Check each option's syntax

   public function testExample() {} uses 'public function testExample() {}' which is correct PHP and Laravel style. Others are invalid PHP or wrong syntax.

3. Final Answer:

   public function testExample() {} -> Option B

4. Quick Check:

   Test methods = public function testName() [OK]

Hint: Test methods start with 'test' and are public functions [OK]

Common Mistakes:

• Using wrong function visibility or missing 'public'
• Using Python syntax in PHP tests
• Incorrect function declaration order

3. Given this Laravel test method, what will be the test result?

public function testSum() {
    $a = 2;
    $b = 3;
    $this->assertEquals(5, $a + $b);
}

medium

A. Test throws a syntax error

B. Test fails because 2 + 3 does not equal 5

C. Test is skipped automatically

D. Test passes because 2 + 3 equals 5

Solution

1. Step 1: Evaluate the sum in the test

   Variables $a and $b are 2 and 3, so $a + $b equals 5.

2. Step 2: Check the assertion

   The assertion expects 5 and compares it to $a + $b, which is 5, so it matches and passes.

3. Final Answer:

   Test passes because 2 + 3 equals 5 -> Option D

4. Quick Check:

   2 + 3 = 5 passes assertion [OK]

Hint: Check math in assertEquals carefully [OK]

Common Mistakes:

• Assuming test fails without checking values
• Confusing assertEquals parameter order
• Thinking syntax error without code issues

4. Identify the error in this Laravel unit test method:

public function testUserName() {
    $user = new User();
    $user->name = 'Alice';
    $this->assertEquals('Alice', $user->username);
}

medium

A. Property 'username' does not exist on User model

B. Missing semicolon after new User()

C. assertEquals parameters are reversed

D. Test method name does not start with 'test'

Solution

1. Step 1: Check User model property usage

   The code sets $user->name but asserts $user->username, which likely does not exist.

2. Step 2: Verify syntax and method name

   There is a semicolon after new User(), and method name starts with 'test', so no syntax or naming errors.

3. Final Answer:

   Property 'username' does not exist on User model -> Option A

4. Quick Check:

   Assert property exists before testing [OK]

Hint: Check property names match exactly in tests [OK]

Common Mistakes:

• Assuming assertEquals parameters order causes error
• Overlooking property name mismatch
• Thinking method name is incorrect

5. You want to test a method that returns a list of active users from the database. Which approach best fits Laravel unit testing principles?

hard

A. Mock the User model's active() method and assert it returns expected data

B. Run the actual database query in the test without mocking

C. Test the method by printing results and checking manually

D. Skip testing because database queries are not testable

Solution

1. Step 1: Understand unit test scope

   Unit tests isolate code parts, so database calls should be mocked to avoid external dependencies.

2. Step 2: Evaluate options for best practice

   Mock the User model's active() method and assert it returns expected data mocks the User model's method and asserts expected results, fitting unit test principles. Run the actual database query in the test without mocking uses real DB, which is integration testing. Test the method by printing results and checking manually is manual and not automated. Skip testing because database queries are not testable is incorrect.

3. Final Answer:

   Mock the User model's active() method and assert it returns expected data -> Option A

4. Quick Check:

   Unit tests mock external calls [OK]

Hint: Mock external dependencies in unit tests [OK]

Common Mistakes:

• Running real database queries in unit tests
• Relying on manual output checks
• Skipping tests for database-related methods