Pytest

Bazel rules for the python test framework Pytest.

Rules

current_py_pytest_toolchain
py_pytest_test
py_pytest_toolchain

Functions

py_pytest_test_suite

current_py_pytest_toolchain

load("@rules_venv//python/pytest:defs.bzl", "current_py_pytest_toolchain")

current_py_pytest_toolchain(name)

A rule for exposing the current registered py_pytest_toolchain.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required

py_pytest_test

load("@rules_venv//python/pytest:defs.bzl", "py_pytest_test")

py_pytest_test(name, deps, srcs, data, config, coverage_rc, env, env_inherit, numprocesses)

A rule which runs python tests using pytest as the py_test test runner.

This rule also supports a build setting for globally applying extra flags to test invocations. Users can add something similar to the following to their .bazelrc files:

build --@rules_venv//python/pytest:extra_args=--color=yes,-vv

The example above will add --colors=yes and -vv arguments to the end of the pytest invocation.

Tips:

It's common for tests to have some utility code that does not live in a test source file. To account for this. A py_library can be created that contains only these sources which are then passed to py_pytest_test via deps.

load("@rules_venv//python:defs.bzl", "py_library")
load("@rules_venv//python/pytest:defs.bzl", "py_pytest_test")

py_library(
    name = "test_utils",
    srcs = [
        "tests/__init__.py",
        "tests/conftest.py",
    ],
    deps = ["@rules_venv//python/pytest:current_py_pytest_toolchain"],
    testonly = True,
)

py_pytest_test(
    name = "test",
    srcs = ["tests/example_test.py"],
    deps = [":test_utils"],
)

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
deps	The list of other libraries to be linked in to the binary target.	List of labels	optional	`[]`
srcs	An explicit list of source files to test.	List of labels	optional	`[]`
data	Files needed by this rule at runtime. May list file or rule targets. Generally allows any target.	List of labels	optional	`[]`
config	The pytest configuration file to use.	Label	optional	`"@rules_venv//python/pytest:config"`
coverage_rc	The pytest-cov configuration file to use.	Label	optional	`"@rules_venv//python/pytest:coverage_rc"`
env	Dictionary of strings; values are subject to `$(location)` and "Make variable" substitution	Dictionary: String -> String	optional	`{}`
env_inherit	Specifies additional environment variables to inherit from the external environment when the test is executed by `bazel test`.	List of strings	optional	`[]`
numprocesses	If set the pytest-xdist argument `--numprocesses` (`-n`) will be passed to the test. Note that the a value 0 or less indicates this flag should not be passed.	Integer	optional	`0`

py_pytest_toolchain

load("@rules_venv//python/pytest:defs.bzl", "py_pytest_toolchain")

py_pytest_toolchain(name, pytest)

A toolchain for the pytest rules.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
pytest	The pytest `py_library` to use with the rules.	Label	required

py_pytest_test_suite

load("@rules_venv//python/pytest:defs.bzl", "py_pytest_test_suite")

py_pytest_test_suite(name, tests, args, data, **kwargs)

Generates a test_suite which groups various test targets for a set of python sources.

Given an idiomatic python project structure:

BUILD.bazel
my_lib/
    __init__.py
    mod_a.py
    mod_b.py
    mod_c.py
requirements.in
requirements.txt
tests/
    __init__.py
    fixtures.py
    test_mod_a.py
    test_mod_b.py
    test_mod_c.py

This rule can be used to easily define test targets:

load("@rules_venv//python:defs.bzl", "py_library")
load("@rules_venv//python/pytest:defs.bzl", "py_pytest_test_suite")

py_library(
    name = "my_lib",
    srcs = glob(["my_lib/**/*.py"])
    imports = ["."],
)

py_pytest_test_suite(
    name = "my_lib_test_suite",
    # Source files containing test helpers should go here.
    # Note that the test sources are excluded. This avoids
    # a test to be updated without invalidating all other
    # targets.
    srcs = glob(
        include = ["tests/**/*.py"],
        exclude = ["tests/**/*_test.py"],
    ),
    # Any data files the tests may need would be passed here
    data = glob(["tests/**/*.json"]),
    # This field is used for dedicated test files.
    tests = glob(["tests/**/*_test.py"]),
    deps = [
        ":my_lib",
    ],
)

For each file passed to tests, a py_pytest_test target will be created. From the example above, the user should expect to see the following test targets:

//:my_lib_test_suite
//:tests/test_mod_a
//:tests/test_mod_b
//:tests/test_mod_c

Additional Notes:

No file passed to tests should be passed found in the srcs or data attributes or tests will not be able to be individually cached.

PARAMETERS

Name	Description	Default Value
name	The name of the test suite	none
tests	A list of source files, typically `glob(["tests/*/_test.py"])`, which are converted into test targets.	none
args	Arguments for the underlying `py_pytest_test` targets.	`[]`
data	A list of additional data for the test. This field would also include python files containing test helper functionality.	`[]`
kwargs	Keyword arguments passed to the underlying `py_test` rule.	none