为什么要在 Android 中拆分单元测试和检测测试文件夹？

Question

Out of curiosity, I am wondering why Android splits instrumented and unit tests folders.

I am well aware of the thus offered ability to have different dependencies for each. Are there any other reasons to do so?

Answer 1

Well for one, unit test can run on its own (no emulator / device needed), so you can easily run a package full of unit tests vs a package mixed although it is possible to combine them. A typical unit test runs around less than a second while a typical instrument test could run as long as hours etc.

Answer 2

Why splits instrumented and unit tests folders?

• unittests run fast (ie 100 tests per second) on the pc without the need to deploy them on device/emulator and can therefore be executed often (ie 100 times a day ie after small changes or before checkin-to-sourcecode-repository)
• instrumentation test are slow (ie 1 test needs 0,5 to 10 seconds) plus deployment on device/emulator is needed (extra 30 seconds). These tests are usually run not that often (ie at night or at the lunch break)