Hey guys,

Unit testing or TDD (Test-driven development) has been a thing for years, hasn't it?

I'll quickly talk about this and share with you guys the experience.

TDD

The practice of TDD is:

• You write test

• You write code

• You run test, test fails, you update the code until the test is passed

But honestly, in real life, we write the code first then write the test 🤣. It is acceptable as well.

Unit Testing

You write a method/function, you write test for that function. That's basically how unit testing works.

Sample method:

function createUser(string $fullName, int $age): User
{
    if ($age < 18) {
        throw new DomainException('User must be an Adult');
    }

    return User::create(['name' => $fullName, 'age' => $age]);
}

To write good and reliable test cases, you would need to cover all the cases:

• When the user's age is below 18

• When the user's age is above or equal to 18

• Data must be created successfully

Example:

public function testCreateUserFailsDueToAgeBelow18()
{
    $this->expectException(DomainException::class);
    createUser('Seth Phat', 15);
}

public function testCreateUserSuccessfully()
{
    $user = createUser('Seth Phat', 18);

    $this->assertNotNull($user);
    $this->assertDatabaseHas('users', [
        'name' => 'Seth Phat',
        'age' => 18,
    ]);
}

Easy, right?

Write as many functions as possible. A minimal function would be super easy to write test.

Pros of having unit testing

• More trust & confidence when releasing features.

• Refactoring would be fun and not scary at all, tests got your back.

  • When you refactor things and the test fails => you know something went wrong in the development phase.

• Same as refactoring: upgrading the framework, library, or language's version. You can list out the out-of-date/breaking changes and take needful actions from them.

  • Imagine upgrading the framework without tests, especially for major versions (eg Laravel 8.x to 9.x), it would cost a lot of time (and money) to do the regression test.

Cons

• Yes yes I know, it takes time.

Conclusion

Even if your project is a big product or an outsourcing one. Let's always write tests.

• Product:

  • Cover things as much as you can

  • Provide as many reliable tests as you can

• Outsourcing:

  • Integration test to test a big flow.

  • or E2E test, to test the important features.

Cheers!