iOS UI Testing in Firefox Focus
I continue contributing to the open source projects, and I got back to Firefox Focus this week. The issue I worked on was listed in July 2018, and nobody had taken it for some reason 🤔 It caught my attention because it asked to add a UI test for one of the pages of the browser, and I haven’t done any testing for iOS apps before. I thought that it would be a good opportunity to learn how to do it.
They added a page for no internet connection error, which is triggered when a user tries to go to a webpage without having the internet.
Firstly, I started my research on how to do UI testing. I found the following story on Medium, which is a nice introduction to iOS testing:
Firefox Focus uses XCUITest library for the UI tests.
After analyzing existing tests in the project, I started writing my own. My first steps were to write a basic test that would just start the app and exit it (because I hadn’t written any other tests). Once I created this basic template for my test, I had to write an actual test function for the No Connection page.
I started with just a basic loading of mozilla.com website. Worked fine 👍 Next, I had to turn off WiFi on the iOS simulator in order to trigger the No Connection page. However, I faced a problem at this step. It turned out that it’s impossible to turn off WiFi just on your iOS simulator neither using XCode nor programmatically 🤭 Instead, you need to disconnect WiFi on the computer, where you compile and build the app. Obviously, that’s not a good option because other tests need the internet connection, and they would fail in this case.
I had to find a solution to this problem. I decided to add a condition, which would check whether there is network or not. If there is no network, the test will run. I found how to implement it in the following blog post:
It's mandatory for all applications to check internet connection is available or not.mobikul.com
Then, I added a few lines of code that checks whether the error page was displayed:
let noInternetConnection = app.staticTexts["The Internet connection appears to be offline."]
XCTAssertEqual("The Internet connection appears to be offline.", noInternetConnection.label)
Let’s walk through these lines of code:
- Tries to load Mozilla website
- Get a label from the No Internet Connection page with the error message
- Assert that this label exists and the value is equalled to “The Internet connection appears to be offline.”
That’s it! You can find the full code in my Pull Request 🙌