I'm experimenting with test sharding on Android and I'm getting pretty weird results:
+ adb -s emulator-5580 shell am instrument -e numShards 2 -e shardIndex 0 -e class com.package.etc.automation.Tests.SanityTest.SanityTest -w com.package.etc.test/android.support.test.runner.AndroidJUnitRunner
com.package.etc.automation.Tests.SanityTest.SanityTest:..........
Time: 306.578
OK (10 tests)
+ adb -s emulator-5582 shell am instrument -e numShards 2 -e shardIndex 1 -e class com.package.etc.automation.Tests.SanityTest.SanityTest -w com.package.etc.test/android.support.test.runner.AndroidJUnitRunner
com.package.etc.automation.Tests.SanityTest.SanityTest:......................
Time: 645.723
OK (22 tests)
As you can see, adb split the tests into two uneven groups. The second one has twice as many tests as the first one and executes twice as long. Not the best parallelism if you ask me.
Is there a possibility to control the distribution of tests, or at least force adb to split the tests evenly?