pytest-reraise

What it is and what it does

pytest-reraise is a pytest plugin that solves a specific threading problem: when you write assertions inside a thread spawned from a test, those assertions fail silently because the exception is raised in the thread, not the main test thread. The plugin provides a `reraise` fixture that acts as a context manager to capture exceptions from worker threads and re-raise them in the main thread at the end of the test, making the test fail as expected.

The plugin supports wrapping functions as decorators, manually triggering re-raises mid-test, handling multiple exceptions (keeping the first), optionally catching exceptions to prevent them from crashing the thread, and accessing or resetting captured exceptions. It's designed for developers writing multi-threaded tests who need pytest to properly detect assertion failures that occur in spawned threads.

Use it for

• Testing concurrent code where worker threads perform assertions that must be validated by the main test
• Verifying that background tasks or thread pools fail correctly when they encounter errors
• Debugging multi-threaded applications by ensuring thread exceptions don't silently pass tests
• Wrapping thread target functions with exception capture to keep threads alive while collecting errors
• Comparing captured thread exceptions against expected error types or messages in test assertions

Worth the install?

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Install

pytest-reraise on PyPI

Before you install

Low friction: pure Python wheel with only pytest as a runtime dependency. Maintenance is stalled—last commit was 2023-02-06 and the package is marked abandoned, though it remains marked Production/Stable and has received no security reports.

License in practice

MIT license is permissive; you may use, modify, and distribute this package freely in commercial and private projects with minimal restrictions.

Quickstart

pip install pytest-reraise

# In your test file:
from threading import Thread

def test_with_thread(reraise):
    def run():
        with reraise:
            assert False
    Thread(target=run).start()

Package facts

Evidence: pytest_reraise-2.1.2-py3-none-any.whl

Tags

More Libraries packages

See also outcome · pytest-assume · pytest-raises · pytest-race · re-assert · pytest-run-parallel · softest · kthread · pytest-rerunfailures · pytest-check