Testfixtures is a collection of helpers and mock objects that are useful when writing automated tests in Python.
The areas of testing this package can help with are listed below:
Comparing, asserting equality and explaining differences
The compare function gives readable feedback when results aren't as expected,
with clear diffs for deeply nested data structures and for objects that don't
normally support comparison. This includes first-class support for pandas and
polars dataframes and numpy arrays. Flexible placeholder objects and helpers
such as like, sequence, generator, Comparison, RoundComparison,
RangeComparison, StringComparison and SequenceComparison let you assert that only part
of a value matters, that a number is within a range or rounded to a precision, or
that a string matches a pattern.
Mocking out objects and methods
Replacer makes it easy to swap out objects, classes or individual methods for the
duration of a test, restoring the originals automatically when it ends. You point them
at the thing being replaced directly rather than at a dotted string, so your type
checker verifies the target and the replacement survives refactoring.
replace_on_class, replace_in_module and replace_in_environ cover common cases such as
methods, module globals and environment variables.
Mocking dates and times
mock_datetime, mock_date and mock_time are drop-in replacements for
the datetime and time APIs, for testing code that depends on the current
date or time. They cover the thorny issues of timezones, non-uniform sequences of mock
time increments, explicit ticking and freezing a point in time so you don't have to
invent them from scratch.
Testing subprocesses
MockPopen lets you test code that uses subprocess.Popen without running
real processes.
Testing command-line scripts
Command drives entry-point scripts end to end and checks their output,
logging, mock calls and return code.
Testing logging
LogCapture captures log messages so you can check what was logged is what you
expected, including from the loguru and structlog libraries.
Testing stream output
OutputCapture captures stream output, such as that from print calls or even
writes made directly to file descriptors, and makes it easy to assert about.
Testing with files and directories
TempDirectory gives you a sandboxed directory to work in. It makes it easy to
read and write files, serialise and deserialise structured data in formats such as
JSON, YAML and TOML, create directory trees, and assert on the contents of both
individual files and whole directories.
Testing exceptions and warnings
ShouldRaise, ShouldAssert, ShouldWarn and ShouldNotWarn check
that a particular exception is raised, that an assertion fails with a particular
message, or that a warning is issued, down to the parameters involved.
Testing when using Django
Helpers for comparing instances of Django models.
Testing when using Twisted
Helpers for making assertions about logging when using Twisted.