Running CTS tests

Trade Federation is a continuous test framework for running tests on Android devices. To run the Compatibility Test Suite (CTS), first read the Trade Federation Overview for an explanation of Tradefed test framework.

To run a test plan:

Set up Devices Under Test (DUTs) as per Android device setup.
Download the released CTS builds onto your Linux host machine and unzip the build to host location.
Connect at least one device. To prepare the DUT:
- Press the home button to set the device to the home screen.
- Don't use the DUT for any other tasks.
- Keep the DUT in a stationary position to avoid triggering sensor activity.
- Point the device camera at an object that can be focused.
- Do not press any keys on the device while the CTS is running. Pressing keys or touching the screen of a DUT interferes with the running tests and may lead to test failures.
Launch the CTS console cts-tradefed script from the folder where the CTS package has been unzipped. On the host's command-line shell, run:
```
./android-cts/tools/cts-tradefed
```
Run the default test plan (contains all test packages):
```
cts-tradefed > run cts
```
- If you want to improve test execution time, you can shard the tests across multiple devices. Sharding requires the host to connect at least two devices, but six or more devices are recommended for efficiency. When sharding more than 1 device:
  - For Android 9 and higher, use the command option
```
--shard-count number_of_shards
```
  - For Android 8.1 and lower, use the command option
```
--shards number_of_shards
```
- If you don't want to run the whole test suite, you can run the CTS plan of your choice from the command line:
```
run cts --plan test_plan_name
```
  To find the test plan name:
  - For Android 7.0 and higher, to see a list of test modules, enter
```
list modules
```
  - For Android 6.0 and lower, to view a list of test plans in the repository, enter
```
list plans
```
  - For Android 6.0 and lower, to view a list of test packages in the repository, enter
```
list packages
```
- For additional command options depending on CTS versions, refer to the console command reference, or under "help all" in the Tradefed console.
  Note: You may save run time in Android 7.0 (Nougat) and higher, by using the run cts-dev command instead of run cts. This command skips preconditions, device-information collection, and all system status checkers. It also runs the tests on only a single ABI. For device validation, avoid this optimization and include all preconditions and checks.
Run multiple Retry sessions until all test modules are completed and the test failure numbers are the same in the last two retry sessions.
- For Android 9 and higher, use
```
run retry --retry session_number --shard-count number_of_shards
```
  Note:The --includ-filter option is not supported in the new retry command.
- For Android 7.0–8.1, use
```
run cts --retry session_number --shards number_of_shards
```
- For additional Retry command options depending on CTS version, see CTS v2 Command Console.
- fTo understand implementation details for CTS retry, see Trade Federation Suite Retry.
View test progress and results reported on the console.