Contributing to PRAW#

PRAW gladly welcomes new contributions. As with most larger projects, we have an established consistent way of doing things. A consistent style increases readability, decreases bug-potential and makes it faster to understand how everything works together.

Setting Up Your Development Environment#

This section will cover the recommended steps to get you started with contributing to PRAW.

Create a Virtual Environment#

It is strongly recommended to use a virtual environment to isolate your development environment. This is a good idea because it will make managing the needed dependencies and their versions much easier. For more information, see the venv documentation. Assuming you have the minimum Python version required for PRAW, you can create a virtual environment with the following commands from the root of the cloned project directory:

python3 -m venv .venv

Next you need to activate the virtual environment. This is done by running the following:

MacOS/Linux:

source .venv/bin/activate

Windows Command Prompt

.venv\Scripts\activate.bat

Install Development Dependencies#

Next, you will need to install the dependencies development dependencies. This is done by running the following:

pip install -e .[dev]

Important

If you are using zsh for your shell, you will need to double-quote .[dev] like so:

pip install -e ".[dev]"

Note

The -e tells pip to install PRAW in an editable state. This will allow for easier testing and debugging. The [dev] extra will install all development dependencies. This includes the dependencies for both linting and testing.

Code Style#

Linting#

PRAW follows PEP 8 and PEP 257 and some PRAW Specific Style Guidelines. pre-commit is used to manage a suite of pre-commit hooks that enforce conformance with these PEPs along with several other checks. Additionally, the pre_push.py script can be used to run the full pre-commit suite and the docs build prior to submitting a pull request.

Note

In order to use the pre-commit hooks and the pre_push.py dependencies, you must either install the development dependencies as outlined in the Install Development Dependencies section above or you must install the [lint] extra manually:

pip install -e .[lint]

To install the pre-commit hooks to automatically run when you commit, run the following:

pre-commit install

To run all the needed checks and to ensure the docs build correctly, run the following:

./pre_push.py

PRAW Specific Style Guidelines#

The following are PRAW-specific guidelines in addition to the PEPs specified in Linting:

  • Within a single file classes are sorted alphabetically where inheritance permits.

  • Within a class, methods are sorted alphabetically within their respective groups with the following as the grouping order:

    • Static methods

    • Class methods

    • Cached properties

    • Properties

    • Instance Methods

  • Use descriptive names for the catch-all keyword argument, e.g., **other_options rather than **kwargs.

  • Methods with more than one argument should have all its arguments sorted alphabetically and marked as keyword only with the * argument. For example:

    class ExampleClass:
    def example_method(
        self,
        *,
        arg1,
        arg2,
        optional_arg1=None,
    ):
        ...

    There is some exceptions to this:

    • If it’s clear without reading documentation what the mandatory positional arguments would be and their order, then they can be positional arguments. For example:

      class ExampleClass:
    def pair(self, left, right):
        ...

    • If there is one or two mandatory arguments and some optional arguments, then the mandatory arguments may be positional (as long as it adheres to the previous point), however, the optional arguments must be made keyword only and sorted alphabetically. For example:

      class Subreddit:
    def submit(
        self,
        title,
        *,
        collection_id=None,
        discussion_type=None,
        draft_id=None,
        flair_id=None,
        flair_text=None,
        inline_media=None,
        nsfw=False,
        resubmit=True,
        selftext=None,
        send_replies=True,
        spoiler=False,
        url=None,
    ):
        ...

Testing#

Contributions to PRAW requires 100% test coverage as reported by Coveralls. If you know how to add a feature, but aren’t sure how to write the necessary tests, please open a pull request anyway so we can work with you to write the necessary tests.

Running the Test Suite#

GitHub Actions automatically runs all updates to known branches and pull requests. However, it’s useful to be able to run the tests locally. The simplest way is via:

pytest

Without any configuration or modification, all the tests should pass. If they do not, please file a bug report.

Adding and Updating Integration Tests#

PRAW’s integration tests utilize Betamax to record an interaction with Reddit. The recorded interaction is then replayed for subsequent test runs.

To safely record a cassette without leaking your account credentials, PRAW utilizes a number of environment variables which are replaced with placeholders in the cassettes. The environment variables are (listed in bash export format):

export prawtest_client_id=myclientid
export prawtest_client_secret=myclientsecret
export prawtest_password=mypassword
export prawtest_test_subreddit=test
export prawtest_username=myusername
export prawtest_user_agent=praw_pytest

By setting these environment variables prior to running pytest, when adding or updating cassettes, instances of mypassword will be replaced by the placeholder text <PASSWORD> and similar for the other environment variables.

To use a refresh token instead of username/password set prawtest_refresh_token instead of prawtest_password and prawtest_username.

When adding or updating a cassette, you will likely want to force requests to occur again rather than using an existing cassette. The simplest way to rebuild a cassette is to first delete it, and then rerun the test suite.

Please always verify that only the requests you expect to be made are contained within your cassette.

There are a few pytest markers that can be used to control how cassettes are recorded or used.

  • @pytest.mark.add_placeholder: Allows you to add custom placeholders to the cassette. This can be useful when you want to record dynamic or generated data, but do not want it to be saved in the cassette. This marker takes at least one keyword argument and can be applied to a test class or individual test methods. It can also be applied multiple times.

  • @pytest.mark.cassette_name: Allows you to set the cassette name. This can be useful when you want to use a cassette that was recorded by another test.

  • @pytest.mark.recorder_kwargs: Allows you to pass additional arguments to the recorder. This can be useful if you need to specify parameters for the Betamax.use_cassette method. Like the add_placeholder marker, this marker can be applied to a test class or individual test methods and can be applied multiple times.

Examples:

@pytest.mark.recorder_kwargs(allow_playback_repeats=True)
class TestClass:
    @pytest.mark.recorder_kwargs(match_requests_on=["uri", "method", "body"])
    def test_example(self):
        ...

    @pytest.mark.cassette_name("TestClass.test_example")
    @pytest.mark.recorder_kwargs(match_requests_on=["uri", "method", "body"])
    def test_example__different_assertion(self):
        ...

    @pytest.mark.add_placeholder(generated_data_a=generate_data_a())
    @pytest.mark.add_placeholder(generated_data_b=generate_data_b())
    def test_example__with_generated_placeholders(self):
        ...

Documentation#

  • All publicly available functions, classes, and modules should have a docstring.

  • All documentation files and docstrings should be linted and formatted by docstrfmt.

  • Use correct terminology. A subreddit’s fullname is something like t5_xyfc7. The correct term for a subreddit’s “name” like python for r/python is its display name.

Static Checker#

PRAW’s test suite comes with a checker tool that can warn you of using incorrect documentation styles (using .. code:: instead of .. code-block::, using /r/ instead of r/, etc.). This is run automatically by the pre-commit hooks and the pre_push.py script.

class tools.static_word_checks.StaticChecker(replace: bool)#

Run simple checks on the entire document or specific lines.

__init__(replace: bool) → None#

Initialize a StaticChecker instance.

Parameters:

replace – Whether or not to make replacements.

check_for_double_syntax(filename: str, content: str) → bool#

Checks a file for double-slash statements (/r/ and /u/).

Parameters:

  • filename – The name of the file to check & replace.

  • content – The content of the file.

Returns:

A boolean with the status of the check.

check_for_noreturn(filename: str, line_number: int, content: str) → bool#

Checks a line for NoReturn statements.

Parameters:

  • filename – The name of the file to check & replace.

  • line_number – The line number.

  • content – The content of the line.

Returns:

A boolean with the status of the check.

run_checks() → bool#

Scan a directory and run the checks.

The directory is assumed to be the praw directory located in the parent directory of the file, so if this file exists in ~/praw/tools/static_word_checks.py, it will check ~/praw/praw.

It runs the checks located in the self.full_file_checks and self.line_checks lists, with full file checks being run first.

Full-file checks are checks that can also fix the errors they find, while the line checks can just warn about found errors.

Files to Update#

AUTHORS.rst#

For your first contribution, please add yourself to the end of the respective list in the AUTHORS.rst file.

CHANGES.rst#

For feature additions, bug fixes, or code removal please add an appropriate entry to CHANGES.rst. If the Unreleased section does not exist at the top of CHANGES.rst please add it. See commit 280525c16ba28cdd69cdbb272a0e2764b1c7e6a0 for an example.

See Also#

Please also read the Contributing Guidelines