IssueTracker

Generally speaking, there are two ways to support test sharding (and AGP UTP should support both).

1. Reactively - distribute tests across different devices on demand.
2. Pre-determined deterministic shards. If there are 100 tests to run and 2 shards (meaning 2 devices) - then the first 50 tests are run on device 1, and the second 50 tests are run on device 2

Reactively distributing tests solves the problem of the first 50 tests taking 10 minutes to execute, while the second group of 50 tests might take 20 minutes. This means 10 minutes of parallelism is wasted because the first group finished early. With reactive test distrubution - there are a pool of devices that consume tests as they are ready so no resources are wasted

Pre-determined deterministic shards are useful because:

pixel2api30 (com.android.build.api.dsl.ManagedVirtualDevice) { .. }

// separate tasks for each of the 2 shards
./gradlew pixel2api30DebugAndroidTestShard1
./gradlew pixel2api30DebugAndroidTestShard2

We could run :pixel2api30DebugAndroidTestShard1 on one build machine, and :pixel2api30DebugAndroidTestShard2 on another. And ensure that all tests are executed. These tasks should also be separately tracked for caching (so :pixel2api30DebugAndroidTest would depend on both of the shard tasks).

My request is that AGP supports both of these use cases (should this be 2 tickets?)