Debugging the Numba Test Suite


Features described here are only implemented for the parallel test runner (e.g. requires the -m flag).

The Numba test suite provides some useful features for debugging test failures or crashes.

Generating JUnit XML Output

You can generate a JUnit-compatible XML report by running the tests with the --junit flag:

$ python -m numba.runtests <args> --junit

This will produce a junit_numba_<timestamp>.xml file containing the test results.

The XML contains some extra metadata as testcase properties:

  • pid: The ID of the worker process running each test case

  • start_time: The start time for each test case relative to when the worker process started

Example of the XML file:

<?xml version='1.0' encoding='utf-8'?>
<testsuites time="20.745398832">
    <testsuite name="numba_testsuite">
        <testcase name="TestUsecases.test_andor" classname="numba.tests.test_usecases"
                <property name="pid" value="73274" />
                <property name="start_time" value="1.337771667" />
        <testcase name="TestUsecases.test_blackscholes_cnd" classname="numba.tests.test_usecases"
                <property name="pid" value="73275" />
                <property name="start_time" value="1.3350285" />

Debugging Timeouts caused by Crashes

If the test suite times out, it may indicate a crashed worker process. In this case, the timeout error will show:

  • The active tests that didn’t finish before the timeout

  • For each affected process ID, the list of tests that process was running

For example:

TimeoutError: Active tests didn't finish before timeout:
- test_foo [PID 1234]

Tests ran by each affected process:
- [PID 1234]: test_bar test_baz test_foo

This information can help reproduce crashes that depend on the test execution order or state within a process. You can retry just the tests that were running in the crashed process.