Mobly Automation Framework

1.13 · active · verified Thu Apr 16

Mobly is an open-source, Python-based test framework for host-driven, end-to-end automated testing, specializing in scenarios requiring multiple devices, complex environments, or custom hardware setups. It is currently at version 1.13 and has a regular release cadence, with recent releases focusing on improvements, bug fixes, and Python 3.11+ compatibility.

Common errors

```
ModuleNotFoundError: No module named 'mobly.snippet_client'
```
cause Using the old, deprecated `snippet_client` import path which was removed after Mobly v1.12.

fix Change the import to `from mobly.controllers.android_device_lib import snippet_client_v2` and update code to use `SnippetClientV2`.
```
AttributeError: 'AndroidDevice' object has no attribute 'snippet_client'
```
cause Attempting to access `ad.snippet_client` on an `AndroidDevice` object after the `snippet_client` module was removed and replaced by `snippet_client_v2`.

fix Ensure you are importing and using `snippet_client_v2` correctly. The common pattern is `self.dut.load_snippet('your_snippet_name', 'com.your.package.name')` which internally uses `snippet_client_v2`.
```
mobly.controllers.android_device.Error: Android device serial "<SERIAL>" is specified in config but is not reachable.
```
cause The specified Android device (by serial or wildcard '*') is not detected by `adb devices` or is not in a ready state (e.g., USB debugging disabled, device offline).

fix Verify `adb` is installed and working (`adb devices`), confirm USB debugging is enabled on the device, and ensure the device is properly connected and recognized. Check `adb logcat` for device-side issues.
```
RuntimeError: Python version must be >= 3.11
```
cause Running Mobly with an older Python version than required.

fix Upgrade your Python environment to version 3.11 or newer. You can use `pyenv` or `conda` for managing Python versions.

Warnings

breaking Python 2 support was completely removed in Mobly v1.11. All legacy Python 2 specific workarounds and APIs are no longer available.
Fix: Migrate all test code to Python 3. Mobly now requires Python 3.11 or newer.
breaking The minimum required Python version for Mobly was bumped to 3.11 in v1.12.3.
Fix: Upgrade your Python environment to 3.11 or later.
deprecated The old Android snippet client (`snippet_client`), `snippet_event`, and `callback_handler` were deprecated in v1.12 and subsequently removed. The new generic Mobly snippet base client and Android snippet client (`snippet_client_v2`, `callback_handler_v2`) are now in use.
Fix: Update imports and code: `snippet_client` -> `snippet_client_v2`, `snippet_event` -> `mobly.snippet.callback_event`, `callback_handler` -> `callback_handler_v2`.
deprecated The `get_available_host_port` function was deprecated in v1.12.3.
Fix: Rely on the operating system to allocate ports instead of using this function.
breaking All SL4A (Scripting Layer for Android) related code was removed in Mobly v1.13.
Fix: Refactor tests to use Mobly Snippet Lib or other modern Android interaction methods instead of SL4A.
gotcha Errors raised from `teardown_class` methods do not trigger the `on_fail` callback.
Fix: Handle exceptions within `teardown_class` explicitly if specific failure logic is required, or ensure `on_fail` logic is sufficient for other test stages.

Install

pip install mobly Install Mobly

Imports

BaseTestClass
```
from mobly import base_test
```
test_runner
```
from mobly import test_runner
```

AndroidDevice

from mobly.controllers import android_device

snippet_client_v2

wrong:

from mobly.controllers.android_device_lib import snippet_client

correct:

from mobly.controllers.android_device_lib import snippet_client_v2

The old snippet_client was deprecated in v1.12 and removed. Use snippet_client_v2 instead.

callback_event
wrong:
```
from mobly import snippet_event
```
correct:
```
from mobly.snippet import callback_event
```
The direct import of snippet_event was deprecated in v1.12. Use mobly.snippet.callback_event instead.
callback_handler_v2
wrong:
```
from mobly import callback_handler
```
correct:
```
from mobly.controllers.android_device_lib import callback_handler_v2
```
The old callback_handler was deprecated in v1.12 and removed. Use callback_handler_v2 instead.

Quickstart

This example demonstrates a basic Mobly test that registers an Android device controller and attempts to display a 'Hello World!' toast message on the device using Mobly Bundled Snippets (MBS). It requires a `sample_config.yml` file to specify the testbed configuration. Ensure 'adb' is configured and 'USB debugging' is enabled on the Android device.

# sample_config.yml
TestBeds:
  - Name: SampleTestBed
    Controllers:
      AndroidDevice: '*'

# hello_world_test.py
from mobly import base_test
from mobly import test_runner
from mobly.controllers import android_device

class HelloWorldTest(base_test.BaseTestClass):
    def setup_class(self):
        # Registering android_device controller declares the test's dependency on Android devices.
        # By default, we expect at least one device is found.
        self.ads = self.register_controller(android_device)
        self.dut = self.ads[0] # Get the first AndroidDevice object
        # Start Mobly Bundled Snippets (MBS) if needed, using the updated MBS_PACKAGE constant
        # You may need to install MBS on your device: 
        # https://github.com/google/mobly-bundled-snippets
        try:
            self.dut.load_snippet('mbs', android_device.MBS_PACKAGE)
        except Exception as e:
            self.log.warning(f"Could not load MBS snippet. Make sure it's installed: {e}")

    def test_hello(self):
        if hasattr(self.dut, 'mbs'):
            self.dut.mbs.makeToast('Hello Mobly World!')
        else:
            self.log.info('MBS not loaded, skipping makeToast. Device detected.')

if __name__ == '__main__':
    # To run, save config as sample_config.yml and this file as hello_world_test.py
    # Then execute: python hello_world_test.py -c sample_config.yml
    test_runner.main()

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