How can the EVA principle be applied in PHP code to improve code readability and maintainability?

Issue: The EVA principle (Explicit, Verifiable, and Automated) can be applied in PHP code to improve code readability and maintainability by making sure that the code is clear, easy to understand, testable, and can be automatically verified through unit tests. Code snippet:

// Explicit: Use meaningful variable names and functions to make the code intentions clear
function calculateArea($length, $width) {
    return $length * $width;
}

// Verifiable: Write unit tests to verify the functionality of the code
class CalculateAreaTest extends PHPUnit_Framework_TestCase {
    public function testCalculateArea() {
        $this->assertEquals(20, calculateArea(4, 5));
    }
}

// Automated: Use continuous integration tools to automatically run tests on code changes