How can you minimize the impact of CI testing on mobile app development timelines?

Firebase Test Lab, Bitrise, App Center, and CircleCI are all great options, in my experience you should use the tool that your team is well versed with, even though none of them have a steep learning curve, things can get tricky if you run into a requirement which is not well documented.

Specifically for mobile app development, I've found fastlane to be the best to handle your automation needs. Of course, you should trigger all the steps to your automation pipeline based on pull requests merged into develop or main.

If you follow the testing pyramid model for guiding what tests you write, you will also have your test suites run faster in CI. Unit tests and compose UI tests that do not need to emulate the Android environment run fastest, so this is where the bulk of your tests should be. On top of that you should have some integration tests for things like app navigation. End-to-end tests should be used most sparingly and should be the equivalent of a quick smoke test pre-release. The test orchestrator ensures each test is run on a clean instrumentation, but there is a time penalty in creating a new instrumentation. If your instrumentation tests instead reset state before each test, the suite will run faster.

In my experience, this is the biggest thorn in development teams' sides. Getting your pull request reviewed becomes a task when it takes an hour for all your tests to finish, dependency injection has been a life saver many a times, I've had good luck with frameworks like quick and nimble as well to write tests faster as they remove the boiler plate code.

Feature flags are a great tool to minimize the impact of CI on development time. Implementing feature flags though can become a nuisance if not done properly, one of the novel ways we have used in the past is to use a bit mask in the headers to avoid feature developers to check for allowed features at the json parsing level.

Utilize Cloud-Based Testing Services Leverage cloud-based testing services that offer parallel testing capabilities. Cloud platforms provide the scalability to run tests concurrently on multiple virtual devices, reducing the overall testing time. This approach allows for faster feedback loops, as testing can be distributed across a wide range of device configurations simultaneously. Cloud-based testing services often integrate seamlessly with CI platforms, providing an efficient solution for minimizing the impact on mobile app development timelines.