Mobile Developer Experience at Slack

This post details the efforts of the Mobile Developer Experience Team (DevXp) to improve the mobile engineering experience at Slack. It focuses on addressing developer pain points related to CI test job duration and test-related failures. For iOS, it describes the integration of Bluepill to shard tests in parallel, reducing execution time to 20 minutes, and the subsequent migration to Bazel with bazel-diff to achieve an average TTM of 9 minutes. For Android, it covers the development of the Fuel test sharder and the adoption of Flank, reducing TTM to under 20 minutes. The post also details the migration from Calabash to Espresso for Android testing, which reduced testing time from ~350 mins to ~60 mins, and the implementation of a system to auto-detect and suppress flaky tests, reducing test failure rates from 57% to 4%.