pytest-bazel 0.1.0

A pytest runner with bazel support

pytest-bazel

A pytest wrapper for supporting bazel's rule_python. This is supposed to be used via PyPI and no bazel rules will be exported for the time being.

Features

Features ported from rules_python_pytest:

• Basic ignoring of external directories.
• Support for pytest 8.0 and pytest 7.0 and handle running of tests when passing the filenames to the runner.
• Test sharding support using pytest-shard.
• Supporting filtering tests via bazel test --test_filter <target>.

Features ported from rules_py:

• Use -p no:cacheprovider

Extra features implementing test_encyclopedia spec:

• TEST_WARNINGS_OUTPUT_FILE is used to output warnings.warn usage.
• TEST_TMPDIR is used
• TEST_RANDOM_SEED is used for predictive tests, consider integrating with https://pypi.org/project/pytest-randomly/.
• short circuit if not running under bazel (see BAZEL_TEST env var).

Extras that have tests:

• No passing of files as args is needed. Pytest discovery is working as expected. Note that this may not scale well with extremely large sandboxes. Please leave feedback in the repo.
• Recommendations on project structure (separate tests dir may facilitate integration with pytest, but this needs further checking).

Usage

Install this by including it into your requirements.in or pyproject.toml file:

pytest-bazel[all]

And then you can use it as follows:

Pattern 1

Using it as an alternative to unittest.main() in a py_test rule.

import pytest_bazel

...

if __name__ == "__main__":
    pytest_bazel.main()

# BUILD.bazel contents
load("@rules_python//python:py_test.bzl", "py_test")

py_test(
    name = "my_test",
    # ...
    deps = ["@pypi//pytest_bazel"],
)

Pattern 2

Using it to create a macro, this shows how to create a replacement for the rules_python_pytest py_pytest_test macro. The benefit is that this defines all of the necessary files in a single place.

# pytest_test.bzl contents
load("@rules_python//python:py_library.bzl", "py_library")
load("@rules_python//python:py_test.bzl", "py_test")
load("@rules_python//python/entry_points:py_console_script_binary.bzl", "py_console_script_binary")

def pytest_test(name, srcs, **kwargs):
    # this is only needed for passing srcs
    deps = kwargs.pop("deps", [])
    data = kwargs.pop("data", [])
    env = kwargs.pop("env", {})
    py_library(
        name = name + ".lib",
        srcs = srcs,
        deps = deps,
        data = data,
        testonly = True,
        **kwargs,
    )

    py_console_script_binary(
        name = name,
        pkg = "@pypi//pytest_bazel",  # assuming your hub repo name is `pypi`.
        script = "pytest_bazel",
        binary_rule = py_test,
        deps = [
            # The test sources are here
            name + ".lib",
            # Add extra test deps below, e.g. for sharding support, etc.
        ],
        data = data + srcs,
        env = env,
        testonly = True,
        # The following is reusing the ideas defined in
        # https://github.com/caseyduquettesc/rules_python_pytest/blob/main/python_pytest/defs.bzl
        args = kwargs.get("args", []) + [
            # Passing of srcs is optional and this is only to show how one
            # would reimplement what `rules_python_pytest` has done.
            "$(location :%s)" % x for x in srcs
        ],
        **kwargs,
    )

# BUILD.bazel contents
load("//:pytest_test.bzl", "pytest_test")

pytest_test(
    name = "my_test",
    # ...
    deps = ["@pypi//pytest_bazel"],
)

Changelog

See changelog.

Contributing

This is right now too early to be contributed to code-wise, but issues welcome describing what you would like to have in this project.

Thanks

Special thanks to rules_python_pytest and rules_py projects that had some great ideas how to integrate with pytest. This attempts to unify all of the approaches.