Exploring PHP 7 Features: Simplify Assertions with Expectations Syntax

Introduction

With the release of PHP 7, developers gained access to many new features and improvements. Among them, the Expectations syntax stands out as one of the most useful additions. It significantly simplifies writing assertions, making code more readable and maintainable. This article explains the basics of the Expectations syntax and demonstrates its advantages through examples.

What is Expectations Syntax?

In PHP, assertions are used to verify conditions within code. Traditional assertions often use the assert() function, which evaluates a condition and throws an error if the condition fails. This approach can be verbose and less intuitive.

The Expectations syntax introduces the expect() function to simplify writing assertions. You can use expect() to verify if a value or expression meets the expected result. When an assertion fails, expect() throws an exception containing detailed error information and the failure location.

How to Use Expectations Syntax

Here are practical examples demonstrating how Expectations syntax improves assertion writing.

Example: Simple Assertion

Suppose we have a function add() that returns the sum of two numbers. We can use Expectations syntax to verify the return value.

function add($a, $b) {
    return $a + $b;
}

// Assert that add() returns 3
expect(add(1, 2))->toBe(3);

In this example, expect() asserts that add(1, 2) equals 3. If the assertion fails, an AssertionException with detailed information is thrown.

Example: Array Assertions

Expectations syntax can also be used to assert arrays. The following example demonstrates using toBe() and toContain() to verify array values.

$data = ['apple', 'banana', 'orange'];

// Assert array length is 3
expect($data)->toHaveLength(3);

// Assert array contains 'banana'
expect($data)->toContain('banana');

Functions like toHaveLength() and toContain() make it easy to verify array length and the presence of specific elements.

Example: Custom Assertion Functions

In addition to built-in assertion functions, you can define custom assertions to meet specific project requirements.

function isEven($num) {
    return $num % 2 == 0;
}

// Assert that 6 is an even number
expect(6)->toBeTrue(isEven);

Here, the isEven() function checks if a number is even, and toBeTrue() asserts that 6 meets this condition.

Conclusion

PHP 7's Expectations syntax provides a simpler and more intuitive way to write assertions. Using expect(), developers can create code that is readable and easy to maintain. The examples above help quickly understand and apply Expectations syntax, making it a powerful tool for improving PHP test code.