"Pytest plugin for testing applications that use Pyodide"
Project description
pytest-pyodide
Pytest plugin for testing applications that use Pyodide
Installation
pytest-pyodide requires Python 3.10+ and can be installed with
pip install pytest-pyodide
You would also one at least one of the following runtimes,
- Chrome and chromedriver
- Firefox and geckodriver
- Safari and safaridriver
- node v14+
Github Reusable workflow
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 0.21.0
build:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: actions/setup-python@v4
with:
python-version: 3.10.2
- uses: mymindstorm/setup-emsdk@v11
with:
version: 3.1.14
- run: pip install pyodide-build==0.21.0
- 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: 0.21.0
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: [0.21.0,0.23.0]
runners: [selenium,playwright]
browsers: [firefox,chrome,node]
os: [ubuntu-latest,macos-latest]
Usage
-
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/0.21.0/pyodide-build-0.21.0.tar.bz2 tar xjf pyodide-build-0.21.0.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_pyodide
Some 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.
Specifying a browser
You can specify a browser runtime using --runtime
(--rt
) commandline option.
Possible options for --runtime
are:
- node (default)
- firefox
- chrome
- safari
- host (do not run browser-based tests)
pytest --runtime firefox
pytest --runtime firefox --runtime chrome
# Adding -no-host suffix will disable running host tests
pytest --runtime chrome-no-host
Running tests with Playwright (optional)
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
Custeom 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.
Examples
See examples
.
License
pytest-pyodide uses the Mozilla Public License Version 2.0.
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