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Installing Percy for Python with Selenium
Importing the Percy selenium library
Creating a new Percy object with a WebDriver instance as a parameter
Calling and configuring Percy snapshots
This library is in beta---we welcome contributions to improve it.
Requires Python >= 2.7.
$ pip install percy
The following assumes that
webdriver is a Selenium webdriver object of some sort (like
webdriver.Chrome()). Proper setup and teardown of Selenium tests is not included here.
First, create a
ResourceLoader object. This is the configuration for how Percy will discover your app's assets.
import percy # Build a ResourceLoader that knows how to collect assets for this application. root_static_dir = os.path.join(os.path.dirname(__file__), 'static') loader = percy.ResourceLoader( root_dir=root_static_dir, # Prepend `/assets` to all of the files in the static directory, to match production assets. # This is only needed if your static assets are served from a nested directory. base_url='/assets', webdriver=webdriver, )
Now, create a
percy.Runner object and initialize a build. This must be done at the beginning of your entire test suite.
percy_runner = percy.Runner(loader=loader) percy_runner.initialize_build()
Then, at the end of your entire test suite, finalize the build (this needs to be run even if tests fail):
During Selenium tests, use
percy_runner.snapshot() in any test to capture the DOM state and send it to Percy for rendering and visual regression testing.
# In a Selenium test, you might visit a page like this (this also assumes we're subclassing # Django's LiveServerTestCase): webdriver.get(self.live_server_url) percy_runner.snapshot()
snapshot also accepts a
name to uniquely identify it across builds:
Done! Now commit and push your branch to run your tests in your CI service, or create a GitHub PR.
Setup default responsive breakpoints for all snapshots:
percy_config = percy.Config(default_widths=[1280, 375]) percy_runner = percy.Runner(loader=loader, config=percy_config)
These are the default responsive widths to be used on every snapshot. They can be overridden on a per-snapshot basis by passing the
widths arg to
To temporarily disable Percy in CI, set the
PERCY_ENABLE=0 environment variable.
See Percy usage in the Sentry repository for a complete example of Percy integrated in a large Django application and with
Updated 9 months ago
To add visual testing to your workflow, we recommend setting up your CI service and source code management system.
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