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Pytest plugin for detecting inadvertent open file handles

Project description

This package provides a plugin for the pytest framework that allows developers to detect whether any file handles or other file-like objects were inadvertently left open at the end of a unit test. It has been moved from the core astropy project since it is of use more generally.


The pytest-openfiles plugin allows for the detection of open I/O resources at the end of unit tests. This is particularly useful for testing code that manipulates file handles or other I/O resources. It allows developers to ensure that this kind of code properly cleans up I/O resources when they are no longer needed.


The pytest-openfiles plugin can be installed using pip:

$ pip install pytest-openfiles

It is also possible to install the latest development version from the source repository:

$ git clone
$ cd pytest-openfiles
$ python ./ install

In either case, the plugin will automatically be registered for use with pytest.


This plugin adds the --open-files option to the pytest command. When running tests with --open-files, if a file is opened during the course of a unit test but that file is not closed before the test finishes, the test will fail.

In some cases certain files are expected to remain open between tests. In order to prevent these files from causing tests to fail, they can be ignored using the configuration file variable open_files_ignore. This variable is added to the [tool:pytest] section of a package’s top-level setup.cfg file.

Files can be ignored using a fully specified filename:

open_files_ignore = "/home/user/monty/output.log"

It is also possible to ignore files with a particular name regardless of where they reside in the file system:

open_files_ignore = "output.log"

In this example, all files named output.log will be ignored if they are found to remain open after a test completes. Paths and filenames can include * and ? as wildcards:

open_files_ignore = "*.ttf"

It is also possible to ignore open files for particular test cases by decorating them with the openfiles_ignore decorator:

import pytest

def test_open_file_and_ignore():
    """We want to ignore this test when checking for open file handles."""

The test function will not be skipped, but any files that are left open by the test will be ignored by this plugin.

Development Status

Travis CI Status

Questions, bug reports, and feature requests can be submitted on github.


This plugin is licensed under a 3-clause BSD style license - see the LICENSE.rst file.

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