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pytest-fail-slow is a pytest plugin for making tests fail that take too long to run. It adds a --fail-slow DURATION command-line option to pytest that causes any & all otherwise-passing tests that run for longer than the given duration to be marked as failures, and it adds a @pytest.mark.fail_slow(DURATION) marker for making an individual test fail if it runs for longer than the given duration. If --fail-slow is given and a test has the @fail_slow() marker, the duration given by the marker takes precedence for that test.

Note that slow tests will still be run to completion; if you want them to instead be stopped early, use pytest-timeout.

A duration can be supplied to the --fail-slow option as either a bare floating-point number of seconds or as a floating-point number followed by one of the following units (case insensitive):

• h, hour, hours
• m, min, mins, minute, minutes
• s, sec, secs, second, seconds
• ms, milli, millisec, milliseconds
• us, μs, micro, microsec, microseconds

Durations passed to the @pytest.mark.fail_slow() marker can be either ints/floats (for a number of seconds) or strings in the same format as passed to --fail-slow.

If pytest-fail-slow marks a test as a failure, the output will include the test's duration and the duration threshold, like so:

________________________________ test_func ________________________________
Test passed but took too long to run: Duration 123.0s > 5.0s

Note: Only the durations for tests themselves are taken into consideration. If a test passes in less than the specified duration, but one or more fixture setups/teardowns take longer than the duration, the test will still be marked as passing.

Installation

pytest-fail-slow requires Python 3.7 or higher and pytest 6.0 or higher. Just use pip for Python 3 (You have pip, right?) to install it:

python3 -m pip install pytest-fail-slow