PHP unit testing best practices

Unit testing is an important part of software development that helps ensure that code is working as expected. Here are some best practices for PHP unit testing:

1. Write testable code: Write code that is easy to test by breaking it down into small, discrete functions or methods. This will make it easier to test individual pieces of functionality and catch bugs early.
2. Use a testing framework: Use a testing framework like PHPUnit to write and run your tests. PHPUnit provides a range of assertions and tools that make it easy to write effective tests.
3. Test all code paths: Ensure that all code paths are tested, including edge cases and error handling. This will help catch bugs that might not be immediately obvious.
4. Use mock objects: Use mock objects to isolate the code you are testing from any dependencies. This will allow you to test the code in isolation and make your tests more reliable.
5. Keep tests simple and focused: Write tests that are simple, focused, and test a single piece of functionality. This will make it easier to understand the tests and catch bugs.
6. Use descriptive test names: Use descriptive names for your tests that clearly explain what the test is testing. This will make it easier to understand what is being tested and why.
7. Use code coverage tools: Use code coverage tools like PHPUnit’s code coverage report to measure the effectiveness of your tests. This will help you identify areas of your code that are not being tested and improve your test suite.

Here is an example of a basic PHPUnit test:

// MathTest.php
use PHPUnit\Framework\TestCase;

class MathTest extends TestCase
{
    public function testAddition()
    {
        $result = 2 + 2;
        $this->assertEquals(4, $result);
    }

    public function testSubtraction()
    {
        $result = 5 - 3;
        $this->assertEquals(2, $result);
    }
}

In this example, we define a simple test case that tests the addition and subtraction operators. We use the assertEquals method to check that the expected result is equal to the actual result. When we run the test suite, PHPUnit will run each test method and report the results.