How to Implement TDD in Laravel and Why it is Important?

Code with confidence: Empower your Laravel application with Test Driven Development

From startups to enterprises, organizations are extensively adopting TDD as a balanced approach to optimize three activities: coding, testing, and designing.

Test-driven development (TDD) is a software development process where you first write an automated test that specifies and validates the behavior of a small piece of code, then writes the code that the test approves. With TDD, you can ensure a correct, robust, and maintainable code. In this article, we will explore how to implement TDD in Laravel.

Why should we use Test Driven Development?

1. Enhanced code reliability: Developers can ensure that their code meets the expected functionality and behavior, reducing bugs and design mistakes and building the right thing in the right way from the start.
2. Faster feedback: It catches errors early on, provides instant feedback, and thus reduces the time and effort required to fix them.
3. More assured code modifications: A comprehensive set of tests provides confidence and assurance when making changes or refactoring code, reducing the risk of new defects and ensuring code meets requirements.
4. Easier refactoring: It helps to detect issues quickly and reduce the risk of introducing new defects during the refactoring process, maintaining code quality and ensuring code behaves correctly.
5. Superior group work: It encourages collaboration and efficiency in software development teams by establishing clear specifications and common goals, reducing ambiguity and misunderstandings, and streamlining the development process.

Prerequisites:

To understand the concept of Test Driven Development in Laravel, you should have a basic understanding of the following:

1. PHPUnit: It is a unit-testing framework for PHP; used for writing tests in Laravel.
2. Object-Oriented Programming (OOP): Having a basic understanding of OOP concepts like classes, objects, inheritance, and interfaces is essential.
3. Software testing: A fundamental knowledge of software testing concepts like unit testing, integration testing, and acceptance testing is important for understanding TDD.

Configuration:

To configure Test Driven Development (TDD) in Laravel, you should follow the below-mentioned steps:

• Install Laravel: The first step is to install Laravel on your machine by running the following command in your terminal:

composer create-project --prefer-dist laravel/laravel <project-name>

• Set up your environment: This step involves configuring your database connection and other settings. You can do this by copying the .env.example file to .env and then editing the settings in the .env file.
• Install PHPUnit: PHPUnit is the unit testing framework for PHP, which should be installed to write and run tests in Laravel. You can do this by running the following command in your terminal:

composer require --dev phpunit/phpunit

• Create a test: For this, you need to create a new PHP file in the tests/ directory. The file name should end with Test.php. In this file, you should define the test methods that describe the behavior of your code.

php artisan make:test ExampleTest

• Run the test: Once you have created a test, you can run it using PHPUnit. To run all tests in the tests/ directory, run the following command in your terminal:

vendor/bin/phpunit

This will run all tests in the tests/ directory and output the results in the terminal.

Getting Started:

To get started with TDD in Laravel, you will need to install PHPUnit, which is a unit-testing framework for PHP. PHPUnit is included with Laravel, so you don’t need to install it separately.

Next, you will need to create a new Laravel project. You can do this using the Laravel new command in your terminal.

Once you have created your project, you can start writing tests for your code. Laravel provides several testing tools that make it easy to write tests for your application.

Let’s look at a simple example to illustrate how TDD works in Laravel. Suppose we want to create a simple blog application. We should have functionality like creating a new blog, getting a specific blog, updating an existing blog, and deleting a blog. So here, we have a PostController.

/**
 * PostController
 */
class PostController extends Controller
{
    /**
     * Function is used to create the blog.
     *
     * @param Request $request
     * @return JsonResponse
     */
    public function createBlog(Request $request): JsonResponse
    {
        $post = Post::create([
            'title' => $request->input('title'),
            'body' => $request->input('body'),
            'user_id' => Auth::id(),
        ]);
        return response()->json($post, 201);
    }

    
    /**
     * Get the blog information by id.
     *
     * @param integer $id
     * @return JsonResponse
     */
    public function getBlogById(int $id): JsonResponse
    {
        $post = Post::findOrFail($id);
        return response()->json($post);
    }

    /**
     * Function is used to update the blog.
     *
     * @param Request $request
     * @param integer $id
     * @return JsonResponse
     */
    public function updateBlog(Request $request, int $id): JsonResponse
    {
        $post = Post::findOrFail($id);
        $post->update([
            'title' => $request->input('title'),
            'body' => $request->input('body'),
        ]);
        return response()->json($post);
    }

    /**
     * Function is used to delete the blog.
     *
     * @param integer $id
     * @return void
     */
    public function deleteBlog(int $id)
    {
        $post = Post::findOrFail($id);
        $post->delete();
        return response()->noContent();
    }
}

Now, let’s write a test case for blog creation.

class BlogTest extends TestCase
{
    /** @test */
    public function a_user_can_create_a_blog_post()
    {
        // Arrange
        $user = factory(User::class)->create();
        $post = [
            'title' => 'My first blog post',
            'body' => 'This is the body of my first blog post.',
        ];

        // Act
        $response = $this->actingAs($user)->post('/createBlog', $post);

        // Assert
        $response->assertStatus(201);
        $this->assertDatabaseHas('posts', $post);
    }
}

In this example, we’re using Laravel’s built-in TestCase class, which provides a set of methods to make testing easier. We’re also using Laravel’s Factory class to create a new user.

The a_user_can_create_a_blog_post test method has three parts: Arrange, Act, and Assert.

In the Arrange section, we’re creating a new user and defining the data for a new blog post.

In the Act section, we’re stimulating a user making a POST request to the /posts endpoint with the new blog post data.

In the Assert section, we’re checking that the response status code is 201 (created), indicating that the blog post was successfully created. We’re also conforming that the new blog post data was inserted into the database.

Let’s write GET method to retrieve a single blog post. Here's an example test:

class BlogTest extends TestCase
{
    public function test_user_can_retrieve_single_blog_post()
    {
        // Arrange
        $post = factory(Post::class)->create();

        // Act
        $response = $this->get("/getBlogById/{$post->id}");

        // Assert
        $response->assertStatus(200);
        $response->assertJson([
            'id' => $post->id,
            'title' => $post->title,
            'body' => $post->body,
        ]);
    }
}

Here, in this example, we’re creating a new blog post using Laravel’s factory method, making a GET request to the /posts/{id} endpoint to retrieve the post, and then checking that the response has a status code of 200 (OK) and that the response JSON data matches the post data we created.

Now let’s move on to the PUT method to update a blog post. Here's an example test:

class BlogTest extends TestCase
{
    public function test_user_can_update_blog_post()
    {
        // Arrange
        $post = factory(Post::class)->create();
        $newData = [
            'title' => 'New title',
            'body' => 'New body',
        ];

        // Act
        $response = $this->put("/updateBlog/{$post->id}", $newData);

        // Assert
        $response->assertStatus(200);
        $this->assertDatabaseHas('posts', array_merge(['id' => $post->id], $newData));
    }
}

In this example, we’re creating a new blog post using Laravel’s factory method, defining some new data to update the post, making a PUT request to the /posts/{id} endpoint to update the post, and then checking that the response has a status code of 200 (OK) and that the post data was updated in the database.

Next, let’s move on to the DELETE method to delete a blog post. Here's an example test:

class BlogTest extends TestCase
{
    public function test_user_can_delete_blog_post()
    {
        // Arrange
        $post = factory(Post::class)->create();

        // Act
        $response = $this->delete("/deleteBlog/{$post->id}");

        // Assert
        $response->assertStatus(204);
        $this->assertDatabaseMissing('posts', ['id' => $post->id]);
    }
}

In this example, we’re creating a new blog post using Laravel’s factory method, making a DELETE request to the /posts/{id} endpoint to delete the post, and then checking that the response has a status code of 204 (No Content) and that the post data was deleted from the database.

What’s Next:

TDD in Laravel is an evolving process, and there are several areas where it could be improved or further developed. Some of the possible next steps for TDD in Laravel include:

1. Integration testing: Integration tests verify that individual pieces of code work together correctly, ensuring that the application works as expected as a whole, making them a valuable addition to a TDD workflow.
2. Behaviour-driven development (BDD): BDD is an extension of TDD that focuses on the expected behavior of an application from the user’s perspective. In Laravel, BDD can be implemented using frameworks like Behat or Codeception.
3. Continuous integration (CI) and continuous deployment (CD): CI/CD is a set of practices that automate the process of testing, building, and deploying code. Integrating TDD with CI/CD can help ensure that your code is always tested and deployed correctly.
4. Test coverage analysis: Test coverage analysis helps you determine how much of your code is covered by tests. This can help you identify areas of your code that need more testing and ensure that your tests are effective.
5. Mocking and dependency injection: In Laravel, Mocking and dependency injection techniques enable the isolation of code parts during testing and can be implemented using libraries like Mockery or PHPUnit’s built-in mocking functionality.

Conclusion

Laravel’s support for test-driven development is valuable for any developer looking to build reliable and high-quality applications. By embracing TDD, you can build better software, catch bugs earlier in the development process, and ensure that your code is robust and reliable.

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