How to do unit testing with PHP?

Unit testing checks the smallest components of the software (such as functions, methods), and PHP can be unit tested through the PHPUnit framework. First install PHPUnit, then create a test class (extended from TestCase), then write a test method starting with "test" and use assertEquals to assert that two values ​​are equal. In a practical case, StringUtilsTest.php tests the method ucfirst() of the StringUtils class; mocks are used to isolate code, such as simulating database dependencies. The sample code shows how to use PHPUnit to test the HttpRequest::get() method, create a mock version of the dependency through a mock object, set the mock return value, and verify the service method call.

Unit testing using PHP

Unit testing is a software testing technique that examines the smallest independent components of the software ( Unit) - function, method or class.

Installing PHPUnit

PHPUnit is a popular PHP unit testing framework. To install it, run the following Composer command:

composer require --dev phpunit/phpunit

Create test classes

Each test class is named with the "Test" suffix and extends from PHPUnit\Framework\TestCase Class:

class SomeClassTest extends PHPUnit\Framework\TestCase
{
    // ...
}

Writing test methods

Each test method starts with "test", followed by the function to be tested Name:

public function testAddNumbers()
{
    $result = someFunction(1, 2);
    $this->assertEquals(3, $result);
}

assertEquals Method asserts that two values ​​are equal.

Run the test

To run the test, use the PHPUnit command:

vendor/bin/phpunit

Practical case: Test string tool class

Consider a helper class called StringUtils that provides a ucfirst method to capitalize the first letter of a string. We can write a unit test to test this method:

StringUtilsTest.php

class StringUtilsTest extends PHPUnit\Framework\TestCase
{
    public function testUcfirst()
    {
        $string = 'hello world';
        $result = StringUtils::ucfirst($string);
        $this->assertEquals('Hello world', $result);
    }
}

Using mocks

Mocks allows you Mock the behavior of external dependencies to isolate your code in unit tests. For example, if you are testing a class that relies on a database, you can use a mock to simulate the database without actually querying it.

Sample code: Testing the getRequest() method using PHPUnit

class HttpServiceTest extends TestCase
{
    public function testGetRequest()
    {
        $request = $this->getMockBuilder(HttpRequest::class)
            ->onlyMethods(['get'])
            ->getMock();

        $request->method('get')
            ->with('name')
            ->willReturn('John Doe');

        $service = new HttpService($request);

        $this->assertEquals('John Doe', $service->getRequest('name'));
    }
}

This example shows how to use a mock object to create a mock version of a dependency, how to set the mock return value, and How to verify method calls of a service.

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