README.md

Patchwork 2.1

composer require antecedent/patchwork

This library allows any function/method call to be intercepted, as if the function were redefined at runtime. It does not depend on any core extensions.

Example of testing-related usage

Patchwork is used primarily to ease the testing of legacy code.

Suppose that a hypothetical ImportService imports a remote resource using file_get_contents(), unless the local copy is sufficiently recent. The latter check is achieved using filemtime().

It follows that these functions are stubborn dependencies of ImportService, at least if they are called the usual way, that is, file_get_contents($path) and not ($this->fileReader)($path).

What makes these dependencies stubborn is that they cannot be displaced using any conventional runtime strategies. Concretely, if ImportService calls file_get_contents(), then there is no non-invasive way of making it call something else instead for testing purposes.

It is easy to avoid this issue and do without Patchwork, as in function __construct($fileReader = 'file_get_contents'). However, when presented with a legacy codebase where it is impractical to perform such refactoring, Patchwork will help:

use function Patchwork\{redefine, restoreAll, always, getFunction};

final class ImportServiceTest extends PHPUnit\Framework\TestCase
{
    private $importService = new ImportServiceTest; // FIXME
    private $calls = [];    

    public function testNoImportOccursIfDataRecent()
    {
        redefine('file_get_contents', [$this, 'logCall']);
        redefine('filemtime', always(strtotime('-2 days')));
        $this->calls = [];
        $this->importService->import();
        $this->assertEmpty($this->calls);
        restoreAll();
    }

    public function logCall()
    {
        $this->calls[] = Patchwork\getFunction();
    }
}