As your application code grows and the number of automated tests increases, the build and test execution time in CI/CD increases. Longer build and test time means slower development speed.

Because UI tests like Espresso need to be run on actual Android devices or Android emulators, the execution time tends to be long.

In this session, I will show you how to dramatically reduce the execution time of UI tests (Espresso) on a cloud-based CI/CD tool (CircleCI) with multiple Android emulators.

・What is UI testing(Test Pyramid) / Espresso
・What are challenges(execution environment, time, flakiness, maintenance, etc)
・Why parallelism is important for UI testing, several ways to run UI tests in parallel(CircleCI, firebase).
・How to add test splitting and parallelism to your Espresso runs using CircleCI

1. Pre-build (/gradlew assembleDebugAndroidTest) to run UI tests
2. Launch multiple Linux VM/Android emulators
3. Split tests based on execution time
4. Run split tests in parallel
5. Upload test results which include execution time