check-duplicate-variables 1.0.1

A tool to detect duplicate variable names within the same scope in Python files

check-duplicate-variables

A Python tool that detects duplicate variable names within the same scope (module or class) in Python files. This tool is designed to help identify potential copy-paste errors, refactoring issues, and maintain code quality in automated testing frameworks, particularly page object models.

Features

• AST-based Analysis: Uses Python's Abstract Syntax Tree (AST) for accurate parsing
• Scope-aware Detection: Identifies duplicates within module-level and class-level scopes separately
• Value Comparison: Reports whether duplicate assignments have the same or different values
• Multiple Assignment Types: Handles standard assignments, type-annotated assignments, tuple unpacking, and attribute assignments
• Recursive Directory Scanning: Automatically scans all Python files in a directory tree
• CI/CD Friendly: Provides exit codes and formatted output suitable for continuous integration pipelines
• Error Handling: Gracefully handles file I/O errors, encoding issues, and syntax errors

Installation

Install from PyPI

pip install check-duplicate-variables

Install from Source

git clone https://github.com/pandiyarajk/check-duplicate-python-variables.git
cd check-duplicate-python-variables
pip install .

Requirements

• Python 3.7 or higher
• No additional packages required (uses only standard library: ast, os, sys, collections, typing)

Usage

Basic Usage

After installation, use the check-duplicate-variables command:

check-duplicate-variables

This will look for a pageobjects directory in the current working directory.

Custom Directory

Specify a custom directory to scan:

check-duplicate-variables /path/to/your/python/files

As a Python Module

You can also run it as a Python module:

python -m check_duplicate_variables [directory]

or

python -m check_duplicate_variables [filepath]

Standalone Script

If you have the standalone script, you can run it directly:

python check_duplicate_variables.py [directory]

Exit Codes

• 0: No duplicates found and no errors encountered
• 1: Duplicates found or I/O/parse errors occurred

Output Format

The tool outputs one line per duplicate variable found:

file_path: variable_name (same values) - line1, line2, line3
file_path: variable_name (different values) - line1, line2

Example Output

pageobjects/login_page.py: username (same values) - 15, 23, 45
pageobjects/login_page.py: password (different values) - 18, 32
pageobjects/dashboard.py: button_text (same values) - 10, 25

• (same values): All assignments have identical values (potential copy-paste error)
• (different values): Assignments have different values (intentional reassignment or bug)

How It Works

1. File Scanning: Recursively walks the specified directory and finds all .py files
2. AST Parsing: Each file is parsed using Python's ast module
3. Variable Tracking: The VariableAnalyzer visitor class traverses the AST and tracks all variable assignments per scope
4. Duplicate Detection: Identifies variables assigned more than once in the same scope
5. Value Comparison: Extracts and normalizes the source code of assigned values to compare them
6. Reporting: Outputs results in a CI-friendly format with line numbers and value comparison status

Supported Assignment Types

The tool detects duplicates in the following assignment patterns:

• Simple assignments: x = 1
• Type-annotated assignments: x: int = 1
• Multiple assignments: x = y = 1
• Tuple unpacking: a, b = 1, 2
• Attribute assignments: self.attr = value
• Subscript assignments: x[i] = value

Use Cases

• Page Object Models: Detect duplicate locators or element definitions in Selenium/Playwright page objects
• Code Quality: Identify copy-paste errors and refactoring opportunities
• Pre-commit Hooks: Integrate into Git pre-commit hooks to catch issues before commit
• CI/CD Pipelines: Add to GitHub Actions, GitLab CI, or other CI/CD workflows
• Code Reviews: Automated detection of duplicate variable definitions

Integration Examples

GitHub Actions

name: Check Duplicate Variables

on: [push, pull_request]

jobs:
  check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-python@v4
        with:
          python-version: '3.11'
      - name: Install check-duplicate-variables
        run: pip install check-duplicate-variables
      - name: Check for duplicate variables
        run: check-duplicate-variables ./src

Pre-commit Hook

Create .git/hooks/pre-commit:

#!/bin/bash
check-duplicate-variables ./pageobjects
if [ $? -ne 0 ]; then
    echo "Duplicate variables detected. Please fix before committing."
    exit 1
fi

Limitations

• Only detects duplicates within the same scope (module or class)
• Does not detect duplicates across different scopes (e.g., module variable vs. class variable with same name)
• Value comparison is based on source code normalization, not runtime evaluation
• Does not handle dynamically generated variable names

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

This project is licensed under the MIT License - see the LICENSE file for details.

Author

Pandiyaraj Karuppasamy

• Email: [e-mail]
• GitHub: @pandiyarajk

Repository

https://github.com/pandiyarajk/check-duplicate-python-variables.git

Changelog

See CHANGE_LOG.md for version history and changes.