Check whether adb forwarding takes effect when hit socket connection failure

[mhaoli]

Check whether adb forwarding takes effect when hit socket connection failure.

Tested E2E locally.

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This change is 

[xianyuanjia]

Reviewable status: 0 of 2 files reviewed, 2 unresolved discussions (waiting on @xpconanfan)

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mobly/controllers/android_device_lib/snippet_client_v2.py line 457 at r1 (raw file):

            f'netstat tulpn | grep ":{self.host_port}"', shell=True
        )
        if not stdout:

What happens when there is a stdout? Seems like it would just fail silently and run into attribute error in the next line.

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mobly/controllers/android_device_lib/snippet_client_v2.py line 460 at r1 (raw file):

          raise errors.Error(
              self._device,
              'The Adb forward command execution does not take effect. Please'

did

Code quote:

does

[mhaoli]

Reviewable status: 0 of 2 files reviewed, 2 unresolved discussions (waiting on @xianyuanjia and @xpconanfan)

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mobly/controllers/android_device_lib/snippet_client_v2.py line 457 at r1 (raw file):

Previously, xianyuanjia wrote…

What happens when there is a stdout? Seems like it would just fail silently and run into attribute error in the next line.

Opps, good catch. Added the logic to raise an exception with default error message and unit test for it.

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mobly/controllers/android_device_lib/snippet_client_v2.py line 460 at r1 (raw file):

Previously, xianyuanjia wrote…

did

Done.

[xianyuanjia]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @mhaoli and @xpconanfan)