testudos
A testing harness for Python packages using uv's isolated environments.
Overview
Testudos runs your test suite across every Python version that is both still supported upstream and compatible with your package. It works out which versions those are by intersecting two sources:
- Currently supported Python versions — from endoflife.date
- Your package's compatibility — the
requires-pythonfield in yourpyproject.toml
Cycles that endoflife.date lists but that have no stable release yet (a
Python still in alpha, beta or rc) are left out unless you ask for them with
--include-prerelease.
Quick start
# Install
uv tool install testudos
# See which versions would be tested, and why
testudos versions
# Run the suite on all of them
testudos run
# Run them concurrently
testudos run --parallel
# Show the exact commands without running anything
testudos run --dry-run
Installation
uv tool install testudos # recommended
pip install testudos
To use testudos coverage combine and testudos coverage report, which shell
out to coverage.py on your machine, install the extra:
uv tool install 'testudos[coverage]'
pip install 'testudos[coverage]'
Collecting coverage during testudos run does not need this — each
isolated environment gets its own copy of coverage.
Requirements
- Python 3.10 or newer
- uv
How it works
For each Python version, testudos runs your tests in an ephemeral environment
created by uv run --isolated:
uv run --isolated --python=3.12 --with pytest --directory /path/to/project pytest
--isolatedbuilds a throwaway environment, so nothing leaks between versions--python=X.Yselects the interpreter, downloading it if needed--with pytestputs the test runner inside that environment, where it can see your project's dependencies
--dry-run prints exactly these commands, built by the same code that runs
them, so what you see is what would execute.
Test dependencies
uv run --isolated installs your project and its runtime dependencies. If
your suite needs anything more — pytest plugins, fixture packages — name it,
either per-invocation or in config:
testudos run --with pytest-asyncio --with pytest-mock
[tool.testudos]
test-dependencies = ["pytest-asyncio", "pytest-cov>=7"]
Usage
Choosing versions
testudos run # auto-detect
testudos run --python 3.11 --python 3.12 # explicit (-p)
testudos run --python 3.14.0rc1 # pre-releases are allowed explicitly
testudos run --include-prerelease # include unreleased cycles when auto-detecting
testudos run --offline # skip the API, use cached or bundled data
testudos run ./path/to/project # a project other than the cwd
testudos versions shows the same resolution as a table, marking each cycle
stable or pre-release and naming any pre-release it left out.
Offline mode is also enabled by setting TESTUDOS_OFFLINE.
Execution
testudos run --parallel # concurrent across versions (-P)
testudos run --parallel --jobs 4 # cap concurrency (-j)
testudos run --no-fail-fast # keep going after a failure (-F)
testudos run --timeout 300 # seconds per version (-t)
testudos run --no-timeout # override a configured timeout
testudos run --verbose # more detail (-v)
testudos run --quiet # suppress failed-test output (-q)
testudos run --dry-run # print commands, run nothing (-n)
Fail-fast is on by default in sequential mode. Versions it skips are reported
as SKIPPED rather than dropped, so the summary always accounts for every
version you asked for. It does not apply in parallel mode, where every version
is already running by the time the first failure is known.
Multiple packages
testudos run --package ./pkg1 --package ./pkg2 # explicit packages (-k)
testudos run ./monorepo --discover # every dir with a pyproject.toml (-d)
testudos run ./pkg1 --package ./pkg2 --package-jobs 2 # cap package concurrency (-J)
testudos run --package ./pkg2 --no-parallel-packages # one package at a time
Package-level and version-level concurrency are independent: --parallel /
--jobs control versions within a package, --parallel-packages /
--package-jobs control packages. Each package keeps its own configuration,
results and coverage data.
Coverage
testudos run --coverage # collect (-c)
testudos run --coverage --coverage-report html
testudos run --coverage --coverage-report html --coverage-report xml
testudos run --coverage --coverage-fail-under 80
testudos run --coverage --coverage-source mypackage # default: src
Formats: term, term-missing, html, xml, json, lcov. Data lands in
.testudos/coverage/. The --coverage-fail-under threshold is checked
against exact totals, so it gives the same verdict whichever report formats
you asked for.
Coverage data can also be managed directly:
testudos coverage combine # merge per-version data
testudos coverage report # generate a report (--format, --fail-under)
testudos coverage clean # remove .testudos/coverage
Machine-readable output
testudos run --format json
testudos run --format json --output results.json # (-o)
testudos run --format json --dry-run
JSON output covers single-package runs, and reports per-version results plus a
summary of passed, failed and skipped counts. It is not available with
--coverage or in multi-package mode.
Private indexes
testudos run --default-index https://pypi.internal.example.com/simple
testudos run --index https://extra.example.com/simple
testudos run --find-links /path/to/wheels
testudos run --no-index --find-links /path/to/wheels
testudos run --index-strategy first-index
Colour
testudos --color run # force colour
testudos --no-color run # disable it
These are options on testudos itself, so they go before the subcommand.
NO_COLOR and FORCE_COLOR are respected too.
Configuration
Everything above can be set in [tool.testudos]:
[project]
requires-python = ">=3.11"
[tool.testudos]
# Version selection
python-versions = ["3.11", "3.12", "3.13"] # override auto-detection
include-prerelease = false # include unreleased cycles
offline = false # never call endoflife.date
# What to run
test-command = "pytest"
test-args = ["-v", "--tb=short"]
test-dependencies = ["pytest-asyncio"] # extra packages per isolated env
timeout = 300 # seconds per version
# How to run it
parallel = false
max-jobs = 4
# Coverage
coverage = false
coverage-combine = true
coverage-report = ["term"]
coverage-fail-under = 80
coverage-source = ["src"]
# Package indexes
default-index = "https://pypi.internal.example.com/simple"
index = ["https://extra.example.com/simple"]
find-links = ["/path/to/wheels"]
no-index = false
index-strategy = "first-index"
CLI options win over configuration. Values are validated on load: a wrong type or an out-of-range value is an error, and an unrecognised key is a warning.
test-command is a single executable name — pytest, nose2, ./run-tests.
To run a module, use test-command = "python" with
test-args = ["-m", "unittest", "discover"].
Documentation
- Architecture — how the pieces fit together, and the decisions behind them
Development
git clone https://github.com/martinristovski/testudos.git
cd testudos
uv sync --extra dev
just ci # lint, type-check, test, dogfood, version check
just test # pytest with coverage
just fix # auto-fix lint and formatting
just dogfood # run testudos on itself
The test suite is hermetic: the endoflife.date API is stubbed and the version
cache is redirected per test, so no test touches the network or your real
~/.cache/testudos.
License
MIT
1 maintainer
Metadata
1 maintainer
Release files for testudos 0.21.0
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