What are some potential pitfalls to avoid when writing PHPUnit tests for a PHP application, particularly in the context of an online shop?

One potential pitfall to avoid when writing PHPUnit tests for a PHP application, especially in the context of an online shop, is not properly mocking external dependencies such as database connections or API calls. This can lead to slow and unreliable tests that are tightly coupled to the external systems. To solve this issue, use PHPUnit's built-in mocking capabilities to create fake objects that simulate the behavior of the external dependencies. This allows you to isolate the code being tested and ensure that your tests run quickly and consistently. 

// Example of properly mocking a database connection in a PHPUnit test

class DatabaseTest extends \PHPUnit\Framework\TestCase {
    public function testDatabaseConnection() {
        // Create a mock object for the database connection
        $databaseMock = $this->getMockBuilder(Database::class)
                            ->disableOriginalConstructor()
                            ->getMock();

        // Set up expectations for the mock object
        $databaseMock->expects($this->once())
                    ->method('query')
                    ->with('SELECT * FROM products')
                    ->willReturn([]);

        // Inject the mock object into the class being tested
        $shop = new Shop($databaseMock);

        // Call the method that interacts with the database
        $products = $shop->getProducts();

        // Assert that the method returns the expected result
        $this->assertEquals([], $products);
    }
}

Keywords

PHPUnit PHP application online shop test coverage edge cases

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