PHP Exception Handling: Using Assertion Exceptions in Test Scenarios

Using assertion exceptions can easily assert exceptions in the PHP testing framework. Use the expectException() method to declare the type of exception expected to be thrown. If it does occur, the test will pass, otherwise it will fail. Using assertion exceptions improves the stability and maintainability of test cases, especially when exceptions are expected.

PHP Exception Handling: Using Assertion Exceptions in Test Scenarios

Exception handling is an important programming technique that can Helps you handle errors during program execution. When writing assertions in PHP testing frameworks like PHPUnit, using exception handling can improve the robustness and maintainability of your test cases.

How to use assertion exceptions

PHPUnit provides a set of assertion exceptions for asserting when an exception is expected. These assertion exceptions can be found in tests/TestCase.php.

To use asserted exceptions, you need to use the expectException() method to declare the type of exception you expect to be thrown. For example:

use PHPUnit\Framework\TestCase;

class MyTest extends TestCase
{
    public function testExceptionIsThrown()
    {
        $this->expectException(\Exception::class);
        throw new \Exception();
    }
}

The test will pass if the expected exception type is indeed thrown. However, if another type of exception is thrown, or no exception is thrown at all, the test will fail.

Practical case

Let us consider a function that uploads a file to the server:

function uploadFile(string $filePath)
{
    if (!file_exists($filePath)) {
        throw new \Exception('File does not exist');
    }
    // ...
}

We want to write a PHPUnit test case to assert that when a file An exception will be thrown when not present:

use PHPUnit\Framework\TestCase;

class FileUploadTest extends TestCase
{
    public function testFileDoesNotExistExceptionIsThrown()
    {
        $this->expectException(\Exception::class);
        uploadFile('non-existent-file.txt');
    }
}

Running this test case will throw the \Exception we expected, and the test will pass.

Conclusion

Use assert exceptions to easily assert exceptions in your PHP testing framework. It helps improve the robustness and maintainability of your test cases and ensures that your tests fail correctly when an exception is expected.

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