Re-Introducing PHPUnit: Getting Started with TDD in PHP

This article provides a modern introduction to PHPUnit for a contemporary PHP development environment. We'll build a simple command-line tool that converts JSON to PHP arrays, demonstrating key PHPUnit concepts along the way.

We assume familiarity with object-oriented PHP (PHP 7 or higher). For a streamlined setup, use Homestead Improved, which pre-installs PHP 7 and simplifies the process. Some command-line usage is involved, but we'll guide you through it.

Key Concepts:

• PHPUnit: A testing framework for PHP that simplifies test creation and execution, promoting code quality and Test-Driven Development (TDD).
• Test-Driven Development (TDD): A methodology where tests are written before the code, guiding development and ensuring expected behavior. Assertions verify expected outcomes.
• Setup: Involves creating a project with Composer, installing PHPUnit as a development dependency (composer require phpunit/phpunit --dev), and configuring phpunit.xml to manage test suites and bootstrapping.
• First Test: Extend PHPUnitFrameworkTestCase, use assertions (assertEquals, etc.) to define expected results, driving functional code development.
• Data Providers: Cleanly organize tests by separating test data from logic. Easily add new test cases without modifying test methods.
• Code Coverage: Reports identify untested code, ensuring comprehensive testing and application robustness.

Test-Driven Development Explained:

TDD involves writing tests to define how code should behave before writing the code itself. Assertions (assertEquals, assertTrue, etc.) check if the code meets expectations. A failed test indicates a need for code changes.

PHPUnit Overview:

PHPUnit provides tools (classes and executables) to simplify test writing and analysis. It generates reports showing code quality, coverage, and more.

Example Application: JSON to PHP Array Converter

We'll create a command-line tool to convert JSON files to PHP arrays. Assume a PHP 7 environment with Composer. If using Homestead Improved, ssh into the VM (vagrant ssh).

1. Project Setup:

   cd Code
   git clone https://github.com/php-pds/skeleton converter
   cd converter
   composer require phpunit/phpunit --dev
   rm bin/* src/* docs/* tests/*

2. Front Controller (index.php in converter/public):

   <?php echo "Hello world";

3. phpunit.xml:

   <?xml version="1.0" encoding="UTF-8"?>
   <phpunit bootstrap="tests/autoload.php">
       <testsuites>
           <testsuite name="converter">
               <directory suffix="Test.php">tests</directory>
           </testsuite>
       </testsuites>
   </phpunit>

4. tests/autoload.php:

   cd Code
   git clone https://github.com/php-pds/skeleton converter
   cd converter
   composer require phpunit/phpunit --dev
   rm bin/* src/* docs/* tests/*

5. composer.json (updated): (Replace template values with your project details)

   <?php echo "Hello world";

6. Run composer dump-autoload

7. First Test (tests/SitePoint/Converter/ConverterTest.php):

   <?xml version="1.0" encoding="UTF-8"?>
   <phpunit bootstrap="tests/autoload.php">
       <testsuites>
           <testsuite name="converter">
               <directory suffix="Test.php">tests</directory>
           </testsuite>
       </testsuites>
   </phpunit>

8. Run Tests (php vendor/bin/phpunit) (Expect failure initially)

9. Implement Converter Class (src/SitePoint/Converter/Converter.php):

   <?php
   require_once __DIR__ . '/../vendor/autoload.php';

10. Re-run tests. (Should now pass)

The remainder of the tutorial details adding more tests, using data providers for cleaner code, and setting up code coverage reports using XDebug. The final sections include FAQs covering TDD and PHPUnit best practices. The complete code is available on Github (link provided in original text).

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