README

A PHP CLI tool that analyzes git changes and outputs affected PHP file paths in formats compatible with PHPUnit, Psalm, ECS, and PHP-CS-Fixer. This enables optimized test and analysis runs by only processing files that are actually affected by changes.

Features

Git Integration: Analyze uncommitted, staged, or branch-based changes
Dependency Analysis: Uses nikic/php-parser to build comprehensive dependency graphs
Multiple Strategies: Choose between conservative, moderate, or minimal analysis depth
Format-Specific Output: Tailored output for PHPUnit, Psalm, ECS, and PHP-CS-Fixer
Configurable Full Scans: Define patterns in config file or CLI to trigger complete scans
Verbose Diagnostics: Clear feedback about what's happening with --verbose mode
PSR-12 Compliant: Clean, readable, and well-structured code

Installation

Via Composer (Recommended)

composer require --dev sebastiaanwouters/diffalyzer

After installation, the binary will be available at vendor/bin/diffalyzer.

From Source

git clone https://github.com/sebastiaanwouters/diffalyzer.git
cd diffalyzer
composer install

Quick Start

# Run only tests affected by your changes
vendor/bin/phpunit $(vendor/bin/diffalyzer --output test)

# Analyze only affected files with Psalm, ECS, or PHP-CS-Fixer
vendor/bin/psalm $(vendor/bin/diffalyzer --output files)
vendor/bin/ecs check $(vendor/bin/diffalyzer --output files)
vendor/bin/php-cs-fixer fix $(vendor/bin/diffalyzer --output files)

Usage

Basic Usage

# Get test files affected by uncommitted changes
vendor/bin/diffalyzer --output test

# Get all affected files (for Psalm, ECS, PHP-CS-Fixer, etc.)
vendor/bin/diffalyzer --output files

With Strategies

# Conservative strategy (default): includes all dependencies
vendor/bin/diffalyzer --output test --strategy conservative

# Moderate strategy: excludes dynamic method calls
vendor/bin/diffalyzer --output test --strategy moderate

# Minimal strategy: only imports and direct inheritance
vendor/bin/diffalyzer --output test --strategy minimal

Git Comparison Options

# Staged files only
vendor/bin/diffalyzer --output test --staged

# Compare branches
vendor/bin/diffalyzer --output test --from main --to feature-branch

# Compare commits
vendor/bin/diffalyzer --output test --from abc123 --to def456

# Compare from specific branch to HEAD
vendor/bin/diffalyzer --output test --from main

Full Scan Pattern

Full-scan patterns can be configured via config file (recommended) or CLI flag:

Via config file (recommended):

# diffalyzer.yml
full_scan_patterns:
  - "*.yml"
  - "config/**"

Via CLI flag (overrides config):

# Using regex patterns (must start with / or #)
vendor/bin/diffalyzer --output test --full-scan-pattern '/.*\.yml$/'
vendor/bin/diffalyzer --output test --full-scan-pattern '/^config\//'
vendor/bin/diffalyzer --output test --full-scan-pattern '/phpunit\.xml/'

# Using glob patterns (simpler, no / or # prefix needed)
vendor/bin/diffalyzer --output test --full-scan-pattern '*.xml'
vendor/bin/diffalyzer --output test --full-scan-pattern 'phpunit.xml'
vendor/bin/diffalyzer --output test --full-scan-pattern 'config/**'

Note: Always use --verbose to see:

Which pattern is being used
Which files changed
Whether the pattern matched any files
Whether full scan was triggered

Integration Examples

PHPUnit

# Run only affected tests
vendor/bin/phpunit $(vendor/bin/diffalyzer --output test)

# With configuration
vendor/bin/phpunit -c phpunit.xml $(vendor/bin/diffalyzer --output test)

Psalm

# Analyze only affected files
vendor/bin/psalm $(vendor/bin/diffalyzer --output files)

# With specific error level
vendor/bin/psalm --show-info=false $(vendor/bin/diffalyzer --output files)

ECS (Easy Coding Standard)

# Check only affected files
vendor/bin/ecs check $(vendor/bin/diffalyzer --output files)

# With fix
vendor/bin/ecs check --fix $(vendor/bin/diffalyzer --output files)

PHP-CS-Fixer

# Fix only affected files
vendor/bin/php-cs-fixer fix $(vendor/bin/diffalyzer --output files)

# Dry run
vendor/bin/php-cs-fixer fix --dry-run $(vendor/bin/diffalyzer --output files)

Command Line Options

Option	Short	Description	Default
`--output`	`-o`	Output format: `test` (test files only) or `files` (all files)	Required
`--strategy`	`-s`	Analysis strategy: `conservative`, `moderate`, `minimal`	`conservative`
`--from`		Source ref for comparison (branch or commit hash)
`--to`		Target ref for comparison (branch or commit hash)	`HEAD`
`--staged`		Only analyze staged files	`false`
`--full-scan-pattern`		Regex (e.g., `/\.xml$/`) or glob pattern (e.g., `*.xml`) to trigger full scan (overrides config)
`--config`	`-c`	Path to config file	Auto-detect
`--verbose`	`-v`	Show detailed diagnostic information (outputs to stderr)	`false`
`--test-pattern`		Custom regex pattern to match test files
`--no-cache`		Disable cache and force full rebuild	`false`
`--clear-cache`		Clear cache before analysis	`false`
`--cache-stats`		Show cache statistics after analysis	`false`
`--parallel`	`-p`	Number of parallel workers for parsing	Auto-detect

Configuration File

Diffalyzer supports configuration files to centralize settings like full-scan patterns. Configuration files are automatically detected in the following order:

.diffalyzer.yml
diffalyzer.yml
config.yml

Or specify a custom path with --config path/to/config.yml.

Example Configuration

# diffalyzer.yml or .diffalyzer.yml
full_scan_patterns:
  # Dependency management files
  - composer.json
  - composer.lock
  - package.json

  # Configuration files (glob patterns)
  - "*.config.php"
  - "config/**"

  # Build files
  - Dockerfile
  - docker-compose.yml

  # Regex patterns (start with / or #)
  - "/\\.(env|config)$/"

Pattern Types

Glob patterns (recommended for simplicity):

composer.json - Exact filename match
*.json - Any file ending with .json
config/** - Any file in config directory (any depth)
src/*.php - PHP files in src directory (one level)

Regex patterns (for advanced matching):

Must start with / or #
/\.config\.(js|ts)$/ - Matches .config.js or .config.ts
/^(config|deploy)\// - Matches files in config/ or deploy/ directories

Complete Override Behavior

When you define patterns in your config file, they completely replace the built-in defaults:

With config file: Only your patterns are used
Without config file: Built-in defaults are used (composer.json, composer.lock)
With CLI --full-scan-pattern: CLI always overrides everything (config + built-in)

To disable full scans entirely:

full_scan_patterns: []

Verbose Mode

Use --verbose (or -v) to see detailed diagnostic information about what diffalyzer is doing:

vendor/bin/diffalyzer --output test --verbose

Verbose output (sent to stderr, won't interfere with stdout):

[diffalyzer] Loaded 3 full-scan pattern(s) from config
[diffalyzer] Detected 5 changed file(s)
[diffalyzer] Analyzing 3 PHP file(s)...
[diffalyzer] Scanned project: found 247 PHP file(s) (0.12s)
[diffalyzer] Built dependency graph (0.45s)
[diffalyzer] Found 8 affected file(s)

[diffalyzer] Performance Metrics:
  Total time: 0.62s
  Scan time: 0.12s
  Parse time: 0.45s
  Changed files: 3
  Affected files: 8

Or when full scan is triggered:

[diffalyzer] Full scan triggered: "composer.json" matched pattern "composer.json"

This makes it much clearer what's happening, especially when you get empty output (which means "run on all files").

Analysis Strategies

Conservative (Default)

Includes all dependency types:

Use statements (imports)
Class inheritance (extends)
Interface implementations
Trait usage
Instantiations (new keyword)
Static calls

Most comprehensive but may include some false positives.

Moderate

Includes:

Use statements (imports)
Class inheritance (extends)
Interface implementations
Trait usage

Excludes dynamic method calls and instantiations.

Minimal

Includes only:

Use statements (imports)
Direct inheritance (extends/implements)

Fastest but may miss some affected files.

Output Behavior

Partial Scan (Normal Mode)

`--output test`

Outputs space-separated test file paths that are affected by the changes.

How it works: The tool uses AST-based dependency analysis to find ALL test files that import or use the affected classes. It does NOT assume file naming conventions or directory structures.

Examples:

Test files that import changed classes
- src/User.php changes (declares Diffalyzer\User)
- tests/UserTest.php imports Diffalyzer\User → included in output
- Works regardless of file names or directory structure
Transitive dependencies
- src/User.php changes
- src/UserCollector.php imports/uses User → affected
- tests/UserCollectorTest.php imports UserCollector → included in output
- Full dependency chain is traversed automatically
Test files that changed directly
- tests/UserTest.php modified → included in output
No assumptions about structure
- Works with tests/, test/, Tests/, Test/, or any directory
- Works with any test file naming convention (as long as it contains "Test.php")
- Works with custom project structures
Data fixtures via PHP classes
- If tests use fixture/factory classes (e.g., UserFixture, UserFactory)
- Changes to those fixture classes are tracked via normal dependency analysis
- When UserFixture.php changes → tests importing it are included
- No special configuration needed

Example output: tests/UserTest.php tests/UserCollectorTest.php tests/Integration/UserFlowTest.php

`--output files`

Outputs space-separated file paths for all affected files (includes both source and test files).

Use this for static analysis tools (Psalm), code style checkers (ECS, PHP-CS-Fixer), or any tool that needs to process all affected files.

Example output: src/Foo/Bar.php src/Baz/Qux.php tests/FooTest.php

Full Scan Mode

When full-scan patterns match or no specific files are needed:

All formats output an empty string
Empty output tells each tool to scan the entire project
Example: phpunit with no arguments runs all tests

Full Scan Triggers:

By default (when no config file is present), these files trigger full scans:

composer.json - Dependencies changed, could affect anything
composer.lock - Dependency versions changed

You can customize this behavior in three ways:

Config file (recommended): Define patterns in diffalyzer.yml - replaces built-in defaults
CLI flag: Use --full-scan-pattern - overrides config and built-in defaults
Disable entirely: Set full_scan_patterns: [] in config

Understanding Empty Output:

Empty output is intentional and can mean two things:

No changes detected - No PHP files were modified
Full scan triggered - A file matched a full-scan pattern

Use --verbose to see which one:

vendor/bin/diffalyzer --output test --verbose
# Output to stderr will show: "No changes detected" or "Full scan triggered: ..."

How It Works

Git Change Detection: Detects changed PHP files using git diff
AST Parsing: Parses all project PHP files using nikic/php-parser
Dependency Graph: Builds forward and reverse dependency maps
Impact Analysis: Traverses graph to find all affected files
Format Output: Generates tool-specific output format

Example Workflow

Step 1: Git detects changes

Changed: src/User.php

Step 2: Dependency analysis

User.php changed
    ↓
UserCollector.php uses User (affected)
    ↓
UserService.php uses UserCollector (affected)

Step 3: Output by format

For --output files (all source files):

src/User.php src/UserCollector.php src/UserService.php

For --output test (test files only):

tests/UserTest.php tests/UserCollectorTest.php tests/UserServiceTest.php

Result: Run only the 3 tests affected by the User.php change, not all 100+ tests in your suite!

Advanced Integration

Makefile

Use the included Makefile for convenient local development:

# Run affected tests
make test-affected

# Run tests for changes from main branch
make test-branch

# Analyze with Psalm
make psalm-affected

# Fix code style
make cs-fix-affected
make ecs-affected

# See all available targets
make help

Pre-commit Hook

Create .git/hooks/pre-commit:

#!/bin/bash

# Run tests on staged files
TESTS=$(vendor/bin/diffalyzer --output test --staged)

if [ -n "$TESTS" ]; then
    echo "Running affected tests..."
    vendor/bin/phpunit $TESTS
    if [ $? -ne 0 ]; then
        echo "Tests failed. Commit aborted."
        exit 1
    fi
fi

exit 0

Make it executable:

chmod +x .git/hooks/pre-commit

Composer Scripts

Add to your composer.json:

{
    "scripts": {
        "test:affected": [
            "@php vendor/bin/phpunit $(vendor/bin/diffalyzer --output test)"
        ],
        "psalm:affected": [
            "@php vendor/bin/psalm $(vendor/bin/diffalyzer --output files)"
        ],
        "cs:fix:affected": [
            "@php vendor/bin/php-cs-fixer fix $(vendor/bin/diffalyzer --output files)"
        ]
    }
}

Then run:

composer test:affected
composer psalm:affected
composer cs:fix:affected

CI/CD Integration

GitHub Actions

See .github/workflows/ci-example.yml for a complete working example. Basic setup:

name: Tests
on: [push, pull_request]
jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0  # Full history for git diff
      - name: Setup PHP
        uses: shivammathur/setup-php@v2
        with:
          php-version: 8.1
      - name: Install Dependencies
        run: composer install
      - name: Run Affected Tests
        run: |
          if [ "${{ github.event_name }}" == "pull_request" ]; then
            TESTS=$(vendor/bin/diffalyzer --output test --from origin/${{ github.base_ref }})
          else
            TESTS=$(vendor/bin/diffalyzer --output test)
          fi

          if [ -n "$TESTS" ]; then
            echo "Running affected tests: $TESTS"
            vendor/bin/phpunit $TESTS
          else
            echo "Running all tests (full scan triggered)"
            vendor/bin/phpunit
          fi

GitLab CI

See .gitlab-ci-example.yml for a complete working example. Basic setup:

variables:
  GIT_DEPTH: 0  # Fetch full git history

test:
  script:
    - composer install
    - |
      if [ -n "$CI_MERGE_REQUEST_TARGET_BRANCH_NAME" ]; then
        BASE_BRANCH="origin/$CI_MERGE_REQUEST_TARGET_BRANCH_NAME"
      else
        BASE_BRANCH="HEAD~1"
      fi

      TESTS=$(vendor/bin/diffalyzer --output test --from $BASE_BRANCH)

      if [ -n "$TESTS" ]; then
        vendor/bin/phpunit $TESTS
      else
        vendor/bin/phpunit
      fi

Troubleshooting

Full-scan pattern not working

Problem: Using --full-scan-pattern but full scan is not triggered.

Solutions:

Use --verbose to debug: This will show you:
```
vendor/bin/diffalyzer --output test --full-scan-pattern '/test\.xml/' --verbose
```
- Which files actually changed
- Which pattern is being used
- Whether the pattern matched
- Whether full scan was triggered
Check pattern syntax:
- Regex patterns must start with / or #: /\.xml$/, /^config\//
- Glob patterns don't need delimiters: *.xml, phpunit.xml, config/**
- When in doubt, use glob patterns (simpler and more intuitive)

Verify the pattern matches your changed files:

# First see what files changed
git status
git diff --name-only

# Then craft a pattern that matches them
# If you changed "phpunit.xml":
vendor/bin/diffalyzer --output test --full-scan-pattern 'phpunit.xml' --verbose
# or
vendor/bin/diffalyzer --output test --full-scan-pattern '/phpunit\.xml/' --verbose

Common pattern examples:

# Match any XML file
--full-scan-pattern '*.xml'
--full-scan-pattern '/\.xml$/'

# Match specific file anywhere
--full-scan-pattern 'phpunit.xml'
--full-scan-pattern '/phpunit\.xml/'

# Match files in directory
--full-scan-pattern 'config/**'
--full-scan-pattern '/^config\//'

# Match multiple extensions (regex only)
--full-scan-pattern '/(\.xml|\.yml)$/'

Pattern doesn't match subdirectories?
- For glob: use config/** not config/* for recursive matching
- For regex: use /^config\// to match anything starting with config/

No tests run but I made changes

Cause: You changed a file that no tests depend on.

Solutions:

Ensure your test files import the classes they test
Try conservative strategy: --strategy conservative
Verify your changes are to tracked files (not untracked/ignored)
Check dependency chain: does a test import your changed class?

All tests run when I change one file

Cause: Full scan was triggered.

Solutions:

Check if you modified composer.json or composer.lock
Check if your change matches --full-scan-pattern
Review changed files: git status
This is by design for critical files

Git errors

Cause: Not in a git repository or no commits exist.

Solutions:

Ensure you're in a git repository: git init
Create an initial commit: git add . && git commit -m "Initial commit"
Verify git is accessible: git --version

Empty output

This is normal behavior and means:

For PHPUnit: No test files affected OR full scan triggered → run all tests
For other tools: No files affected OR full scan triggered → analyze all files

Always handle empty output by running the full tool:

TESTS=$(vendor/bin/diffalyzer --output test)
if [ -n "$TESTS" ]; then
    vendor/bin/phpunit $TESTS
else
    vendor/bin/phpunit  # Full run
fi

Tips & Best Practices

Use Makefile: Convenient shortcuts for common operations
CI/CD Branch Comparison: Use --from origin/main in pipelines
Start Conservative: Begin with conservative strategy, optimize later if needed
Fixture Classes: Modern fixtures (PHP classes) are automatically tracked
Pre-commit Hooks: Use --staged flag for pre-commit validation
Full Scan Patterns: Add critical config files to trigger complete scans
Test Imports: Ensure test files import the classes they test for proper tracking
Git History: Use fetch-depth: 0 in CI to enable proper branch comparison

Requirements

PHP Version Support

Diffalyzer supports the following PHP versions:

PHP Version	Status	Tested
8.1	✅ Supported	✅ Yes
8.2	✅ Supported	✅ Yes
8.3	✅ Supported	✅ Yes
8.4	✅ Supported	✅ Yes
8.0 or lower	❌ Not supported	-

All versions are actively tested in CI/CD with both prefer-lowest and prefer-stable dependency strategies.

Other Requirements

Git: Any recent version
Composer: 2.0 or higher

Dependencies

nikic/php-parser ^5.0
symfony/console ^6.4 || ^7.0
symfony/process ^6.4 || ^7.0
symfony/finder ^6.4 || ^7.0
symfony/yaml ^6.4 || ^7.0

License

MIT

Author

Created by Sebastiaan Wouters for optimized PHP testing and analysis workflows.

sebastiaanwouters / diffalyzer

Maintainers

Details

README

Features

Installation

Via Composer (Recommended)

From Source

Quick Start

Usage

Basic Usage

With Strategies

Git Comparison Options

Full Scan Pattern

Integration Examples

PHPUnit

Psalm

ECS (Easy Coding Standard)

PHP-CS-Fixer

Command Line Options

Configuration File

Example Configuration

Pattern Types

Complete Override Behavior

Verbose Mode

Analysis Strategies

Conservative (Default)

Moderate

Minimal

Output Behavior

Partial Scan (Normal Mode)

--output test

--output files

Full Scan Mode

How It Works

Example Workflow

Advanced Integration

Makefile

Pre-commit Hook

Composer Scripts

CI/CD Integration

GitHub Actions

GitLab CI

Troubleshooting

Full-scan pattern not working

No tests run but I made changes

All tests run when I change one file

Git errors

Empty output

Tips & Best Practices

Requirements

PHP Version Support

Other Requirements

Dependencies

License

Author

`--output test`

`--output files`