WordPress Coding Standards (PHPCS + WPCS)

Model note: Setup and config steps are mechanical (haiku). Fixing sniff violations across many files works fine on haiku. Only reach for sonnet/opus when violations involve subtle logic (e.g. escaping inside complex SQL builders).

Configure and enforce the WordPress Coding Standards via PHP_CodeSniffer. WPCS is required for WP.org submission and is the canonical style guide for all WordPress PHP code.

When to use

• "Set up PHPCS for my plugin", "add WordPress coding standards", "configure phpcs.xml".
• "Fix sniff violations", "run phpcbf", "auto-fix coding standards".
• "Add PHPCS to GitHub Actions / CI".
• "Why is PHPCS flagging X?", "suppress a false-positive sniff".
• Pre-submission audit: "is my code style WP.org–compliant?"

Not for: PHPStan static analysis or type checking — use wp-phpstan-stubs. Security auditing beyond style issues — use wp-plugin-audit.

Method

1. Install

composer require --dev squizlabs/php_codesniffer wp-coding-standards/wpcs dealerdirect/phpcodesniffer-composer-installer

dealerdirect/phpcodesniffer-composer-installer auto-registers WPCS paths so no manual --config-set is needed. Verify:

vendor/bin/phpcs -i
# should list: WordPress, WordPress-Core, WordPress-Docs, WordPress-Extra

2. Configure phpcs.xml.dist

Place at project root. This is the canonical config file (.dist allows local phpcs.xml override).

<?xml version="1.0"?>
<ruleset name="My Plugin">
    <description>WordPress Coding Standards for My Plugin</description>

    <!-- What to scan -->
    <file>.</file>
    <exclude-pattern>vendor/*</exclude-pattern>
    <exclude-pattern>node_modules/*</exclude-pattern>
    <exclude-pattern>build/*</exclude-pattern>
    <exclude-pattern>*.min.js</exclude-pattern>
    <exclude-pattern>*.min.css</exclude-pattern>
    <exclude-pattern>tests/bootstrap.php</exclude-pattern>

    <!-- PHP version target -->
    <config name="testVersion" value="7.4-"/>

    <!-- Ruleset -->
    <rule ref="WordPress-Extra">
        <!-- Suppress if you use short array syntax (WP allows it since WP 5.5) -->
        <!-- <exclude name="Generic.Arrays.DisallowShortArraySyntax"/> -->
    </rule>
    <rule ref="WordPress-Docs"/>

    <!-- Text domain for i18n sniffs -->
    <rule ref="WordPress.WP.I18n">
        <properties>
            <property name="text_domain" type="array" value="my-plugin"/>
        </properties>
    </rule>

    <!-- Minimum WP version for deprecated functions -->
    <rule ref="WordPress.WP.DeprecatedFunctions">
        <properties>
            <property name="minimum_supported_version" value="5.9"/>
        </properties>
    </rule>

    <!-- Prefix all globals -->
    <rule ref="WordPress.NamingConventions.PrefixAllGlobals">
        <properties>
            <property name="prefixes" type="array" value="my_plugin,MyPlugin"/>
        </properties>
    </rule>

    <!-- Show sniff codes in output (for targeted suppression) -->
    <arg value="ps"/>
    <arg name="extensions" value="php"/>
    <arg name="colors"/>
</ruleset>

3. Run

# Check
vendor/bin/phpcs

# Auto-fix (safe mechanical fixes only — review after)
vendor/bin/phpcbf

# Single file or directory
vendor/bin/phpcs includes/class-my-class.php

# Show full sniff code for each violation (useful for writing suppressions)
vendor/bin/phpcs --report=full -s

4. Inline suppression

Suppress only when the sniff is a genuine false positive, not to hide real issues.

// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- escaped in template
echo $pre_escaped_html;

// phpcs:disable WordPress.DB.DirectDatabaseQuery
$wpdb->query( $wpdb->prepare( "DELETE FROM {$wpdb->prefix}my_table WHERE id = %d", $id ) );
// phpcs:enable WordPress.DB.DirectDatabaseQuery

Common false positives and correct suppression codes:

5. Common sniff violations and fixes

Missing nonce verification:

// Bad
$value = sanitize_text_field( $_POST['field'] );

// Good
if ( ! isset( $_POST['my_plugin_nonce'] ) || ! wp_verify_nonce( sanitize_key( $_POST['my_plugin_nonce'] ), 'my_action' ) ) {
    wp_die( esc_html__( 'Security check failed.', 'my-plugin' ) );
}
$value = sanitize_text_field( wp_unslash( $_POST['field'] ) );

Missing `wp_unslash()` before sanitize:

// Bad  — sanitize_text_field on slashed data
$val = sanitize_text_field( $_POST['field'] );

// Good
$val = sanitize_text_field( wp_unslash( $_POST['field'] ) );

Unescaped output:

echo $title;                            // Bad
echo esc_html( $title );               // Good
echo wp_kses_post( $html_content );    // Good for HTML

Yoda conditions:

if ( $value == true ) {}   // Bad
if ( true == $value ) {}   // Good (Yoda)
if ( $value ) {}           // Also fine

Incorrect hook comment spacing:

add_action('init', 'my_fn');             // Bad — no spaces inside parens
add_action( 'init', 'my_fn' );          // Good

Misaligned array `=>` / assignment blocks:

// Bad — WPCS flags Generic.Formatting.MultipleStatementAlignment
$args = array(
    'id' => 1,
    'post_type' => 'post',
);

// Good — double arrows aligned within the block
$args = array(
    'id'        => 1,
    'post_type' => 'post',
);

Always keep => (and consecutive =) aligned within a block — phpcbf fixes this automatically. Never hand-collapse them to single spaces to "tidy" the code; WPCS just re-flags it.

6. GitHub Actions CI

# .github/workflows/phpcs.yml
name: PHPCS

on: [push, pull_request]

jobs:
  phpcs:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: shivammathur/setup-php@v2
        with:
          php-version: '7.4'
          tools: composer
      - run: composer install --no-interaction --prefer-dist
      - run: vendor/bin/phpcs

7. IDE integration

PHPStorm: Settings → PHP → Quality Tools → PHP_CodeSniffer → set path to vendor/bin/phpcs. Enable "Inspections → PHP → PHP Code Sniffer validation".

VS Code: Install shevaua.phpcs extension. Set phpcs.executablePath to ./vendor/bin/phpcs in workspace settings.

Notes

• WordPress-Extra is a superset of WordPress-Core; always use WordPress-Extra unless you have a specific reason to be less strict.
• WordPress-Docs is separate — it enforces PHPDoc blocks. Include it for WP.org submissions.
• WPCS sniffs for i18n (WordPress.WP.I18n) catch missing text domains and non-translatable strings — complement to wp-plugin-audit Dimension B.
• WP.org review does not run PHPCS automatically, but reviewers check style manually and will reject poorly formatted code. PHPCS passing is a strong signal of submission readiness.
• For WooCommerce extensions, add WooCommerce-Core ruleset if available (woocommerce/woocommerce-sniffs).

References

• references/ci-phpcs.md — PHPCS in GitHub Actions: minimal workflow, PHP×WP matrix, caching, and failure triage
• references/phpcs-config-examples.md — phpcs.xml.dist configurations: WP.org-ready minimal, WooCommerce extension, and custom sniff exclusion patterns
• references/wpcs-sniffs.md — WordPress Coding Standards sniff reference: ruleset hierarchy, key sniff descriptions, and common // phpcs:ignore patterns