Astropy Testing Tools

This section is primarily a reference for developers that want to understand or add to the Astropy testing machinery. See Testing Guidelines for an overview of running or writing the tests.

Details

The dependencies used by the Astropy test runner are provided by a separate package called pytest-astropy (see Pytest Plugins). This package provides the pytest dependency itself, in addition to several pytest plugins that are used by Astropy, and will also be of general use to other packages.

Since the testing dependencies are not actually required to install or use Astropy, in the pyproject.toml file they are not included under the [project] section in dependencies. Instead, they are listed under the [project.optional-dependences] in named sections such as test or dev_all.

In particular the test dependencies are the minimal set of dependencies for running astropy tests and you would use this primarily to check that tests pass without the optional dependencies. This is not common and would normally be done with tox -e test.

astropy.tests.helper Module

To ease development of tests that work with Astropy, the astropy.tests.helper module provides some utility functions to make tests that use Astropy conventions or classes easier to work with, e.g., functions to test for near-equality of Quantity objects.

The functionality here is not exhaustive, because much of the useful tools are either in the standard library, pytest, or numpy.testing. This module contains primarily functionality specific to the astropy core package or packages that follow the Astropy package template.

Conversion Guide

Some long-standing functionality has been removed. The following table maps them to what you should use instead.

Removed	Use this
astropy.io.ascii.tests.common.raises	pytest.raises
astropy.tests.disable_internet	pytest_remotedata.disable_internet
astropy.tests.helper.catch_warnings	pytest.warns
astropy.tests.helper.enable_deprecations_as_exceptions	https://docs.pytest.org/en/stable/warnings.html
astropy.tests.helper.ignore_warnings	https://docs.pytest.org/en/stable/warnings.html
astropy.tests.helper.raises	pytest.raises
astropy.tests.helper.remote_data	pytest.mark.remote_data
astropy.tests.helper.treat_deprecations_as_exceptions	https://docs.pytest.org/en/stable/warnings.html
astropy.tests.plugins.display	pytest-astropy-header package

Reference/API

astropy.tests.helper Module

Functions

assert_follows_unicode_guidelines(x[, roundtrip])	Test that an object follows our Unicode policy.
assert_quantity_allclose(actual, desired[, ...])	Raise an assertion if two objects are not equal up to desired tolerance.
check_pickling_recovery(original, protocol)	Try to pickle an object.
generic_recursive_equality_test(a, b, ...)	Check if the attributes of a and b are equal.
pickle_protocol(request)	Fixture to run all the tests for protocols 0 and 1, and -1 (most advanced).

Astropy Test Runner

When executing tests with packagename.test the call to pytest is controlled by the astropy.tests.runner.TestRunner class.

The TestRunner class is used to generate the packagename.test function, the test function generates a set of command line arguments to pytest. The arguments to pytest are defined in the run_tests method, the arguments to run_tests and their respective logic are defined in methods of TestRunner decorated with the keyword decorator. For an example of this see TestRunnerBase. This design makes it easy for packages to add or remove keyword arguments to their test runners, or define a whole new set of arguments by subclassing from TestRunnerBase.

Reference/API

astropy.tests.runner Module

Classes

TestRunner(*args, **kwargs)	A test runner for astropy tests.
TestRunnerBase(*args, **kwargs)	The base class for the TestRunner.
keyword([default_value, priority])	A decorator to mark a method as keyword argument for the TestRunner.

Class Inheritance Diagram