PHP CodeSniffer - Sniffs for testable code

Introduction

This project provides sniffs for some design patterns that improve unit test code testability:

• Use dependency injection (do not create instances using new)
• Limit the length for a call chain ($this->property->service->method->troubles)
• Do not call methods of the same class (this is a sign that your code is too complicated and you should split it in different services)
• Not use static calls (Service::method())
• Use only public methods (private methods cannot be really unit tested, and they indicate that you should be thinking about creating a new service)

It also provides two other sniffs, useful for CI environments:

• Check that a test case exists for every class
• Check that there is at least one test for every method

How to use

1. Install PHPCodeSniffer
2. Install phpcs-testability using Composer

composer require --dev elijahb/phpcs-testability

3. Add the standard to your custom PHPCodeSniffer ruleset.xml file

<rule ref="./vendor/elijahb/phpcs-testability"/>

Recommendations

You could also use another two sniffs to complement the ones in this projects:

• Generic.Metrics.NestingLevel (with a nesting level of 2)
• Generic.Metrics.CyclomaticComplexity (with a complexity level of 3)

Using all this sniffs, ideally inside a CI environment, you will be assured to have maintainable and fully unit tested code.