PHP_CodeSniffer: Detect code standards violations

PHP_CodeSniffer (PHPCS) is a widely used tool to ensure that PHP code follows coding standards like PSR-12, among others. In this article, learn how to install PHP_CodeSniffer locally, globally, and in Docker, set PSR-12 as the default, configure your project to report errors, automatically fix issues with PHPCBF, and use XML reports.

Installing PHP_CodeSniffer

Local Installation via Composer

To install PHP_CodeSniffer for a specific project, run the following command in your project's root directory:

composer require --dev "squizlabs/php_codesniffer=*"

This installs PHP_CodeSniffer as a development dependency in your project.

Global Installation via Composer

To use PHP_CodeSniffer across multiple projects, you can install it globally:

composer global require "squizlabs/php_codesniffer=*"

After global installation, ensure the directory ~/.composer/vendor/bin is in your PATH. Add the following line to your ~/.bashrc (or ~/.zshrc for Zsh users):

export PATH="$PATH:$HOME/.composer/vendor/bin"

Then reload your shell configuration:

source ~/.bashrc

Installation with Docker

If you're using Docker, you can include PHP_CodeSniffer in your image. Here's an example Dockerfile:

FROM php:8.1-fpm

# Install Composer and PHP_CodeSniffer
COPY --from=composer:2 /usr/bin/composer /usr/bin/composer
RUN composer global require "squizlabs/php_codesniffer=*"

# Configure the PATH
RUN echo 'export PATH="$PATH:$HOME/.composer/vendor/bin"' >> $HOME/.bashrc

CMD ["php-fpm"]

This configuration ensures that PHP_CodeSniffer is globally available when you run the container.

Setting the PSR-12 Standard

PSR-12 is the recommended coding standard by PHP-FIG for PHP code formatting. To set PHP_CodeSniffer to use PSR-12, run the following command:

phpcs --standard=PSR12

Alternatively, configure it in your phpcs.xml file:

<?xml version="1.0"?>
<ruleset name="PSR12 Coding Standard">
    <rule ref="PSR12"/>
    <file>src/</file>
</ruleset>

Using the XML Configuration File

You can customize PHP_CodeSniffer with an XML configuration file, allowing you to disable certain checks, add features like progress bars, and color output.
Example of phpcs.xml:

<?xml version="1.0"?>
<ruleset name="Custom Coding Standards">
    <description>PHPCS Custom Ruleset Example</description>

    <!-- PSR-12 Standard -->
    <rule ref="PSR12"/>

    <!-- Color the result output -->
    <arg name="colors" />

    <!-- Show progress of the run -->
    <arg value="ps" />

    <!-- Code directory -->
    <file>src/</file>

    <!-- Ignore file and class comment errors -->
    <rule ref="Squiz.Commenting.FileComment.Missing">
        <exclude-pattern>*/src/*</exclude-pattern>
    </rule>
    <rule ref="Squiz.Commenting.ClassComment.Missing">
        <exclude-pattern>*/src/*</exclude-pattern>
    </rule>
</ruleset>

Now, when you run the command, you'll see a progress bar and colored output in the terminal, along with using the PSR-12 standard.

Code Example: Before and After PHPCBF

Original Code (Before)

<?php
namespace MyApp;

class MyClass {
    public function myFunction() {
        $var = "Hello World!";
        echo $var;
    }
}

After Running PHPCBF

To automatically fix issues found by PHP_CodeSniffer, use the following command:

phpcbf --standard=PSR12 src/MyClass.php

Corrected Code (After)

<?php

namespace MyApp;

class MyClass
{
    public function myFunction()
    {
        $var = "Hello World!";
        echo $var;
    }
}

PHPCBF automatically corrects the formatting to conform with the PSR-12 standard by adjusting indentation, spacing, and proper bracket placement.

Generating a Summary XML Report

PHP_CodeSniffer can generate a summary XML report, which is useful for CI/CD pipelines or automated code analysis.
Configuring XML Summary Reports

To configure PHP_CodeSniffer to generate a summary XML report, add the following configuration to your phpcs.xml file:

<?xml version="1.0"?>
<ruleset name="Custom Coding Standards with Summary">
    <rule ref="PSR12"/>

    <!-- Generate a summarized XML report -->
    <arg name="report" value="summary"/>
    <arg name="report-file" value="phpcs-summary.xml"/>

    <file>src/</file>
</ruleset>

When you run phpcs, it will generate a phpcs-summary.xml file that contains a summary of the violations found.

Conclusion

PHP_CodeSniffer is a powerful tool for ensuring PHP code quality, allowing you to follow coding standards like PSR-12 and customize your checks using an XML configuration file. With it, you can automate code style correction and generate useful reports for reviews and continuous integration.

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