click-type-test

Table of Contents

• Overview
• Installation
• Usage
• License

Overview

click-type-test allows you to test that your click options and arguments match your type annotations.

It is named by the trio of things which it supports:

• click: build a CLI
• type: add type annotations
• test: test that the first two match

Installation

click-type-test only works on Python 3.10+ .

On supported python versions, it should be installed with

pip install click-type-test

Usage

Install the package and then use click_type_test to extract annotation data and check it against your commands.

from click_type_test import check_param_annotations
from foopkg import mycommand

def test_mycommand_annotations():
    check_param_annotations(mycommand)

check_param_annotations raises a click_type_test.BadAnnotationError if an annotation does not match.

Version Guarding

Just because click-type-test only works on certain pythons does not mean that your application, tested with it, is also restricted to those python versions.

You can guard your usage like so (under pytest):

import pytest
import sys
from foopkg import mycommand

@pytest.mark.skipif(
    sys.version_info < (3, 10),
    reason="click-type-test requires py3.10+",
)
def test_mycommand_annotations():
    from click_type_test import check_param_annotations
    check_param_annotations(mycommand)

Extending And Adjusting With AnnotatedParamType and AnnotatedOption

The type deductions made by click-type-test are not always going to be correct. But rather than skipping options or parameters, it's better to pass along the information needed if possible.

Custom parameter types can support usage with click-type-test by implementing the AnnotatedParamType protocol.

Similarly, custom click.Option subclasses can support specialized usage by implementing the AnnotatedOption protocol.

The path you take will depend a bit on the precise needs of your CLI, but it generally should be possible to tune click-type-test to correctly understand your CLI.

ExplicitlyAnnotatedOption

However, the simplest way to use AnnotatedOption is to use the ExplicitlyAnnotatedOption class, which takes an extra init parameter, type_annotation, like so:

import typing
import click
from click_type_test import ExplicitlyAnnotatedOption

def _str_to_bool_callback(
    ctx: click.Context, param: click.Parameter, value: typing.Any
) -> bool | None:
    if value is None:
        return None
    return value.lower() in ("yes", "true", "on", "1")

@click.command
@click.option(
    "--bar",
    callback=_str_to_bool_callback,
    cls=ExplicitlyAnnotatedOption,
    type_annotation=bool,
)
def foo(*, bar: bool | None) -> None:
    ...

Note how type_annotation is used to override the normal deduction that --bar is a string, but the default for --bar is still understood to be None!

AnnotatedParamType

If you have a custom ParamType, extend it like so and it will have first-class support in click-type-test:

# TODO!

AnnotatedOption

If you have a custom subclass of Option already, you won't be able to use cls=ExplicitlyAnnotatedOption. To handle this case, just have your subclass of Option implement the same AnnotatedOption protocol, like so:

# TODO!

License

click-type-test is distributed under the terms of the MIT license.