Flutter integration test with Firebase Test Lab & Codemagic CI/CD. Learn how to write and execute tests using the new integration_test package. We’re going to execute them both locally and also in a more production-grade setup with Firebase Test Lab and Codemagic CI/CD so that you can be fully confident that every piece of code you commit to a repository passes the tests on multiple devices, OS versions, screen sizes, orientations and locales.
Unit tests, widget tests, integration tests - that’s the testing pyramid you’re probably familiar with. The first two have always been quite easy to write and quick to execute. However, integration tests, which are the focus of this tutorial, have had a fair share of their problems - they used to be unnecessarily hard to write and impossible to run on device farms such as Firebase Test Lab. That is, until we had the integration_test package!
Very quick intro to Flutter’s integration tests
Unit tests are for testing the non-UI logic of your app. Widget tests verify the behavior of a single widget. Both of these are quite low-level and can often deal with intricacies that are only familiar to developers and testers. Flutter’s integration tests test the UI flow of the app from the user perspective. In fact, we could say that they simply simulate a user who’s just regularly using the app.
I think the term “integration test”, the way it’s used around Flutter, is rather unfortunate. While they do indeed test the integration of all the classes and widgets, a much more expressive name would be “UI flow test” because that’s exactly what’s being tested.
Unlike unit and widget tests, integration tests run on an actual device or an emulator. This makes them relatively expensive to run - both time-wise and financially. In addition, they test the big picture of the app (just as if it was used by an actual physical user) so while they are immensely useful in finding out about errors that affect the user, integration tests give you very little information about what actually went wrong. That’s the reason why integration tests are not enough on their own but they’re a great complement to unit and widget tests.
What you’ll learn
In this tutorial, you will learn how to write and execute tests using the new integration_test package. We’re going to execute them both locally and also in a more production-grade setup with Firebase Test Lab and Codemagic CI/CD so that you can be fully confident that every piece of code you commit to a repository passes the tests on multiple devices, OS versions, screen sizes, orientations and locales. The app we’re going to be working with is very simple. It’s already written for you in the starter project you can get from above.
After inputting a text and clicking on the FAB, the user is taken to another page where the same text is displayed. After navigating back, the input is clear. If there is nothing written in the text field but the user still wants to navigate to the other page, an error message is displayed. How does the description above sound to you? Makes sense, right? It simply describes the flow of the app. That’s great, because this is exactly what we’re going to check by writing integration tests. Nothing more, nothing less and everything will be tested from the user’s perspective.
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