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Run a sample App Percy build with Appium and Python

Get hands-on experience on running App Percy with Appium and Python using our sample repository

Prerequisites

Before you start, ensure that you have the following installed:

With App Percy, you can automate the visual testing of app applications, ensuring visual consistency across different releases and preventing visual regressions. This page demonstrates how to use App Percy to run visual tests on a sample app application.

Run your App Percy build

Follow these steps to clone the sample App Percy application, run a build, and view the results of the visual comparison:

Clone the sample application

Clone the sample application and install the required dependencies:

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Upload the sample application

Upload the sample application to BrowserStack App Automate:

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After the command runs successfully, you get a response similar to the following:

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Make a note of the app url.

To know more about uploading an app to App Automate, refer to the Upload an App REST API documentation.

Create an App Percy project

Sign in to Percy and create a new app project, for example, test-project. After you’ve created the project, you’ll be shown a Percy Access Token. Use it in the next step.

Create an App Percy project

Set Percy token as an environment variable

Export the token environment variable:

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Usually this would only be set up in your CI environment, but to keep things simple we’ll configure it in your local shell so that Percy is enabled in your local environment.

Generate the first build

Check out a new branch for your work in this tutorial (we’ll call this branch tutorial-example), then run tests & take screenshots:

git checkout -b tutorial-example

Since you are using Appium, your Appium capabilities and configuration keys look like the example below. Use your text editor to edit tests/android.py & tests/ios.py to update USER_NAME, ACCESS_KEY and APP URL with BrowserStack User name, Access key, and App URL that you received in step 1.

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In general, your Appium Test Script would look like this:

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Now, it is time to run your tests.

make test-android
make test-ios

This will run the app’s Appium Python tests, which contain calls to create Percy screenshots. The screenshots will then be uploaded to Percy for comparison. Percy will use the PERCY_TOKEN you used in Step 4 to know the organization and project. Internally, Percy will use something similar to npx percy:app:exec Appium Python ui_tests.py.

You can view the screenshots in Percy now if you want, but there will be no visual comparisons yet, since this is the first time you are running these tests. You’ll see that Percy shows you that these screenshots come from your tutorial-example branch.

Modify the sample application

Now, it’s time to introduce some visual changes to your app. Replace the search_input.send_keys in your test script as shown below.

search_input.send_keys("BrowserStack again")
search_input.send_keys("BrowserStack again")

Commit your changes

Create a commit with the changes.

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Run tests again

Run the tests with screenshots again.

make test-android
make test-ios

This will run the tests again and take new screenshots of our modified application. The new screenshots will be uploaded to Percy and compared with the previous screenshots, showing any visual diffs.

At the end of the test run output, you will see logs from Percy confirming that the screenshots were successfully uploaded. The logs will also give you a direct URL to check out any visual diffs.

View visual differences on dashboard

Visit your project in Percy and you’ll see a new build with visual comparisons between the two runs. Click anywhere on the Build 2 row (we are assuming here that you are using a new project to test things out). You can see the original screenshots on the left, and the new screenshots on the right.

Percy has highlighted what’s changed visually in the app! Screenshots with the largest changes are shown first You can click on the highlight to reveal the underlying screenshot.

View visual differences

If you scroll down, you’ll see that no other test cases were impacted by our changes to text. The unchanged screenshots are shown under an Unchanged filter and are hidden by default.

Congratulations!

From here, you can try making your own changes to the app and tests, if you like. If you do, re-run the tests and you’ll see any visual changes reflected in Percy.

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