flake8-close-io-buffers

A Flake8 plugin to detect unclosed IO buffers in your Python code. This tool helps ensure that IO objects (such as io.BytesIO and io.StringIO) are properly closed either via a context manager or an explicit .close() call.

Features

• Detects Unclosed IO Objects:
  Reports an error (IO100) when an IO object is instantiated but not closed.

• Supports Different Import Styles:
  Works with both:

  • Qualified imports:

    import io
    io.BytesIO()
    

  • Direct imports:

    from io import BytesIO, StringIO
    BytesIO()
    

• Multiple Assignment Support:
  Correctly handles cases where IO objects are assigned to variables, including tuple/list assignments.

Installation

You can install the plugin from PyPI:

pip install flake8-close-io-buffers

Usage

Once installed, Flake8 will automatically load the plugin. Run Flake8 on your Python files as usual:

flake8 your_python_file.py

Configuration

By default, Flake8 may not display errors from custom plugins. To ensure that IO100 errors are reported, add the following to your Flake8 configuration file (e.g., .flake8, setup.cfg, or tox.ini):

[flake8]
extend-select = IO100

Or, run Flake8 with the select flag:

flake8 --select=IO100 your_python_file.py

Example

Consider the following code in example.py:

import io

def foo():
    io.BytesIO()  # Unclosed IO object: will trigger IO100 error

Running Flake8:

flake8 --select=IO100 example.py

Will produce an error like:

example.py:4:5: IO100 unclosed IO object instantiation not assigned to a variable

Running Tests

The project uses pytest for testing. To run the tests:

1. Ensure you have the development dependencies installed (e.g., pytest).
2. From the project root, run:

pytest

Contributing

Contributions are welcome! Please feel free to open issues or submit pull requests on GitHub.

License

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