android_device_service.md

Mobly Android Device Service

This tutorial shows how to use the service mechanism in Mobly's AndroidDevice controller.

Purpose

Mobly's AndroidDevice controller is a Python module that lets users interact with Android devices with Python code.

Often times, we need long-running services associated with AndroidDevice objects that persist during a test, e.g. adb logcat collection, screen recording. Meanwhile, we may want to alter the device's state during the test, e.g. reboot.

AndroidDevice services makes it easier to implement long-running services.

Usage

Implement your service per the BaseService interface.

Here is a dummy service example:

my_service.py

class Configs:
  def __init__(self, secret=None):
    self.secret = secret


class MyService(base_service.BaseService):
  """Dummy service demonstrating the service interface."""
  def __init__(self, device, configs=None):
    self._device = device
    self._configs = configs
    self._is_alive = False

  def get_my_secret(self):
    return self._configs.secret

  @property
  def is_alive(self):
    """Override base class."""
    return self._is_alive

  def start(self):
    """Override base class."""
    self._is_alive = True

  def stop(self):
    """Override base class."""
    self._is_alive = False

Once you have your service class, you can register your service with the ServiceManager. Let's say we already have an AndroidDevice instance ad:

ad.services.register('secret_service',
                     my_service.MyService,
                     my_service.Configs(secret=42))

After registration, you can interact with the service instance:

ad.services.secret_service.is_alive # True
ad.services.secret_service.get_my_secret() # 42

When the ad reboots or gets destroyed, the service manager will handle the lifecycle changes of each service instance. So users don't have to explicitly write code to handle device state changes for each service, which makes the test verbose.

The service interface also has optional methods pause and resume for services that are sensitive to device disconnect without reboot. For more details, see the docstrings of the BaseService interface.