+---------------------------------------------------------------------------------------+----------------------+ | Description | Identifier | +=======================================================================================+======================+ | File should be read and decoded correctly. | unreadable | +---------------------------------------------------------------------------------------+----------------------+ | A preconditions expects a subset of function's arguments. | pre-invalid-arg | +---------------------------------------------------------------------------------------+----------------------+ | A snapshot expects at most an argument element of the function's arguments. | snapshot-invalid-arg | +---------------------------------------------------------------------------------------+----------------------+ | If a snapshot is defined on a function, a postcondition must be defined as well. | snapshot-wo-post | +---------------------------------------------------------------------------------------+----------------------+ | A capture function must be defined in the contract. | snapshot-wo-capture | +---------------------------------------------------------------------------------------+----------------------+ | A postcondition expects a subset of function's arguments. | post-invalid-arg | +---------------------------------------------------------------------------------------+----------------------+ | If a function returns None, a postcondition should not expect result as argument. | post-result-none | +---------------------------------------------------------------------------------------+----------------------+ | If a postcondition expects result argument, the function should not expect it. | post-result-conflict | +---------------------------------------------------------------------------------------+----------------------+ | If a postcondition expects OLD argument, the function should not expect it. | post-old-conflict | +---------------------------------------------------------------------------------------+----------------------+ | An invariant should only expect self argument. | inv-invalid-arg | +---------------------------------------------------------------------------------------+----------------------+ | A condition must be defined in the contract. | no-condition | +---------------------------------------------------------------------------------------+----------------------+ | File must be valid Python code. | invalid-syntax | +---------------------------------------------------------------------------------------+----------------------+

Usage

Pyicontract-lint parses the code and tries to infer the imported modules and functions using astroid library <https://github.com/PyCQA/astroid>_. Hence you need to make sure that imported modules are on your PYTHONPATH before you invoke pyicontract-lint.

Once you set up the environment, invoke pyicontract-lint with a list of positional arguments as paths:

.. code-block:: bash

pyicontract-lint \
    /path/to/some/directory/some-file.py \
    /path/to/some/directory/another-file.py

You can also invoke it on directories. Pyicontract-lint will recursively search for *.py files (including the subdirectories) and verify the files:

.. code-block:: bash

pyicontract-lint \
    /path/to/some/directory

By default, pyicontract-lint outputs the errors in a verbose, human-readable format. If you prefer JSON, supply it --format argument:

.. code-block:: bash

pyicontract-lint \
    --format json \
    /path/to/some/directory

If one or more checks fail, the return code will be non-zero. You can specify --dont_panic argument if you want to have a zero return code even though one or more checks failed:

.. code-block:: bash

pyicontract-lint \
    --dont_panic \
    /path/to/some/directory

To disable any pyicontract-lint checks on a file, add # pyicontract-lint: disabled on a separate line to the file. This is useful when you recursively lint files in a directory and want to exclude certain files.

Module `icontract_lint`

The API is provided in the icontract_lint module if you want to use pycontract-lint programmatically.

The main points of entry in icontract_line module are:

check_file(...): lint a single file,
check_recursively(...): lint a directory and
check_paths(...): lint files and directories.

The output is produced by functions output_verbose(...) and output_json(...).

Here is an example code that lints a list of given paths and produces a verbose output:

.. code-block:: python

import pathlib
import sys

import icontract_lint

errors = icontract_lint.check_paths(paths=[
    pathlib.Path('/some/directory/file.py'),
    pathlib.Path('/yet/yet/another/directory'),
    pathlib.Path('/another/directory/another_file.py'),
    pathlib.Path('/yet/another/directory'),
])

output_verbose(errors=errors, stream=sys.stdout)

The full documentation of the module is available on readthedocs <https://pyicontract-lint.readthedocs.io/en/latest/>_.

Installation

Install pyicontract-lint with pip:

.. code-block:: bash

pip3 install pyicontract-lint

Development

Check out the repository.
In the repository root, create the virtual environment:

.. code-block:: bash

python3 -m venv venv3

Activate the virtual environment:

.. code-block:: bash

source venv3/bin/activate

Install the development dependencies:

.. code-block:: bash

pip3 install -e .[dev]

We use tox for testing and packaging the distribution. Run:

.. code-block:: bash

tox

We also provide a set of pre-commit checks that lint and check code for formatting. Run them locally from an activated virtual environment with development dependencies:

.. code-block:: bash

./precommit.py

The pre-commit script can also automatically format the code:

.. code-block:: bash

./precommit.py  --overwrite

Versioning

We follow Semantic Versioning <http://semver.org/spec/v1.0.0.html>_. The version X.Y.Z indicates:

X is the major version (backward-incompatible),
Y is the minor version (backward-compatible), and
Z is the patch version (backward-compatible bug fix).

Keywords

design-by-contract precondition postcondition validation lint

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