Pytest plugin for testing applications that use Pyodide
pytest-pyodide requires Python 3.10+ and can be installed with
pip install pytest-pyodide
You would also need one at least one of the following runtimes:
pytest-pyodide also supports testing on github actions by means of a reusable workflow in /.github/workflows/main.yml This allows you to test on a range of browser/OS combinations without having to install all the testing stuff, and integrate it easily into your CI process.
In your github actions workflow, call it with as a aseparate job. To pass in your build wheel use an upload-artifact step in your build step.
This will run your tests on the given browser/pyodide version/OS configuration. It runs pytest in the root of your repo, which should catch any test_*.py files in subfolders.
jobs:
# Build for pyodide 0.24.1
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
with:
python-version: 3.11
- uses: mymindstorm/setup-emsdk@v11
with:
version: 3.1.45
- run: pip install pyodide-build==0.24.1
- run: pyodide build
- uses: actions/upload-artifact@v3
with:
name: pyodide wheel
path: dist
# this is the job which you add to run pyodide-test
test:
needs: build
uses: pyodide/pytest-pyodide/.github/workflows/main.yaml@main
with:
build-artifact-name: pyodide wheel
build-artifact-path: dist
browser: firefox
runner: selenium
pyodide-version: 0.24.1
If you want to run on multiple browsers / pyodide versions etc., you can either use a matrix strategy and run main.yaml as above, or you can use testall.yaml. This by default tests on all browsers (and node) with multiple configurations. If you want to reduce the configurations you can filter with lists of browsers, runners, pyodide-versions as shown below.
test:
needs: build
uses: pyodide/pytest-pyodide/.github/workflows/testall.yaml@main
with:
build-artifact-name: pyodide wheel
build-artifact-path: dist
pyodide-versions: "0.23.4, 0.24.1"
runners: "selenium, playwright"
browsers: "firefox, chrome, node"
os: "ubuntu-latest, macos-latest"
First you need a compatible version of Pyodide. You can download the Pyodide build artifacts from releases with,
wget https://github.com/pyodide/pyodide/releases/download/0.24.1/pyodide-build-0.24.1.tar.bz2
tar xjf pyodide-build-0.24.1.tar.bz2
mv pyodide dist/
You can then use the provided fixtures (selenium, selenium_standalone) in tests,
def test_a(selenium):
selenium.run("assert 1+1 == 2") # run Python with Pyodide
which you can run with
pytest --dist-dir=./dist/
run_in_pyodideSome tests simply involve running a chunk of code in Pyodide and ensuring it
doesn't error. In this case, one can use the run_in_pyodide decorate from
pytest_pyodide, e.g.
from pytest_pyodide import run_in_pyodide
@run_in_pyodide
def test_add(selenium):
assert 1 + 1 == 2
In this case, the body of the function will automatically be run in Pyodide. The
decorator can also be called with a packages argument to load packages before
running the test. For example:
from pytest_pyodide import run_in_pyodide
@run_in_pyodide(packages = ["regex"])
def test_regex(selenium_standalone):
import regex
assert regex.search("o", "foo").end() == 2
You can also use @run_in_pyodide with
pytest.mark.parametrize, with hypothesis, etc. @run_in_pyodide MUST be the
innermost decorator. Any decorators inside of @run_in_pyodide will be have no
effect on the behavior of the test.
from pytest_pyodide import run_in_pyodide
@pytest.mark.parametrize("x", [1, 2, 3])
@run_in_pyodide(packages = ["regex"])
def test_type_of_int(selenium, x):
assert type(x) is int
The first argument to a @run_in_pyodide function must be a browser runner,
generally a selenium fixture. The remaining arguments and the return value of
the @run_in_pyodide function must be picklable. The arguments will be pickled
in the host Python and unpickled in the Pyodide Python. The reverse will happen
to the return value. The first selenium argument will be None inside the
body of the function (it is used internally by the fixture). Note that a
consequence of this is that the received arguments are copies. Changes made to
an argument will not be reflected in the host Python:
@run_in_pyodide
def mutate_dict(selenium, x):
x["a"] = -1
return x
def test_mutate_dict():
d = {"a" : 9, "b" : 7}
assert mutate_dict(d) == { "a" : -1, "b" : 7 }
# d is unchanged because it was implicitly copied into the Pyodide runtime!
assert d == {"a" : 9, "b" : 7}
You can also use fixtures as long as the return values of the fixtures are
picklable (most commonly, if they are None). As a special case, the function
will see the selenium fixture as None inside the test.
If you need to return a persistent reference to a Pyodide Python object, you can
use the special PyodideHandle class:
@run_in_pyodide
def get_pyodide_handle(selenium):
from pytest_pyodide.decorator import PyodideHandle
d = { "a" : 2 }
return PyodideHandle(d)
@run_in_pyodide
def set_value(selenium, h, key, value):
h[key] = value
@run_in_pyodide
def get_value(selenium, h, key):
return h[key]
def test_pyodide_handle(selenium):
h = get_pyodide_handle(selenium)
assert get_value(selenium, h, "a") == 2
set_value(selenium, h, "a", 3)
assert get_value(selenium, h, "a") == 3
This can be used to create fixtures for use with @run_in_pyodide.
It is possible to use run_in_pyodide as an inner function:
def test_inner_function(selenium):
@run_in_pyodide
def inner_function(selenium, x):
assert x == 6
return 7
assert inner_function(selenium_mock, 6) == 7
However, the function will not see closure variables at all:
def test_inner_function_closure(selenium):
x = 6
@run_in_pyodide
def inner_function(selenium):
assert x == 6
return 7
# Raises `NameError: 'x' is not defined`
assert inner_function(selenium_mock) == 7
Thus, the only value of inner @run_in_pyodide functions is to limit the scope
of the function definition. If you need a closure, you will have to wrap it in a
second function call.
You can copy files to the pyodide filesystem using the copy_files_to_pyodide decorator. This takes two arguments - a list of (src,destination) pairs. These can be any of: 1) A filename, 2) A folder name, which is copied to the destination path (along with all subdirectories if recurse_directories is True), 3) A glob pattern, which will fetch all files matching the pattern and copy them to a destination directory, whilst preserving the folder structure.
If you set install_wheels to True, any .whl files will be installed on pyodide. This is useful for installing your package.
from pytest_pyodide.decorator import copy_files_to_pyodide
@copy_files_to_pyodide(file_list=[(src,dest)],install_wheels=True,recurse_directories=True)
This plugin also supports running standard pytest tests on pyodide in a browser. So if you have an existing codebase and you want to check if your pyodide build works, just run it like this:
# Make the emscripten/wasm32 wheel in the dist folder
pyodide build
# the following code
# a) copies the test_path directory and subfolders to a Pyodide instance, and
# b) installs any wheels in the dist subfolder so that this package is available on the Pyodide VM
pytest --run-in-pyodide test_path --runtime <runtime> --dist-dir=<pyodide/dist>
You can specify a browser runtime using --runtime (--rt) commandline option.
Possible options for --runtime are:
pytest --runtime firefox
pytest --runtime firefox --runtime chrome
# Adding -no-host suffix will disable running host tests
pytest --runtime chrome-no-host
By default, the tests will be run with Selenium. It is possible to run tests with playwright instead as follows.
First install playwright browsers
python -m playwright install --with-deps
Then use the --runner argument to specify to run tests with playwright.
pytest --runner playwright
Custom test marks supported by pytest-pyodide:
pytest.mark.driver_timeout(timeout): Set script timeout in WebDriver. If the
test is known to take a long time, you can extend the deadline with this marker.
pytest.mark.xfail_browsers(chrome="why chrome fails"): xfail a test in
specific browsers.
See examples.
See compatibility table.
pytest-pyodide uses the Mozilla Public License Version 2.0.
FAQs
Pytest plugin for testing applications that use Pyodide
We found that pytest-pyodide demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 2 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
PyPI confirms no security flaws were exploited in the Ultralytics supply chain attack and highlights improvements for safer package publishing.
Security News
Research
The Socket Research Team breaks down a malicious wrapper package that uses obfuscation to harvest credentials and exfiltrate sensitive data.
Research
Security News
Attackers used a malicious npm package typosquatting a popular ESLint plugin to steal sensitive data, execute commands, and exploit developer systems.