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Capture logcat messages while logcat collection was suspended #1001

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15 changes: 14 additions & 1 deletion mobly/controllers/android_device_lib/services/logcat.py
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Original file line number Diff line number Diff line change
Expand Up @@ -63,6 +63,7 @@ def __init__(self, android_device, configs=None):
self._adb_logcat_process = None
self._adb_logcat_file_obj = None
self.adb_logcat_file_path = None
self._last_connection_time = None
# Logcat service uses a single config obj, using singular internal
# name: `_config`.
self._config = configs if configs else Config()
Expand Down Expand Up @@ -247,9 +248,14 @@ def _start(self):
# In debugging mode of IntelijIDEA, "patch_args" remove
# double quotes in args if starting and ending with it.
# Add spaces at beginning and at last to fix this issue.
cmd = ' "%s" -s %s logcat -v threadtime -T 1 %s >> "%s" ' % (
if self._last_connection_time is not None:
t_argument_value = self._last_connection_time
else:
t_argument_value = '1'
cmd = ' "%s" -s %s logcat -v threadtime -T "%s" %s >> "%s" ' % (
adb.ADB,
self._ad.serial,
t_argument_value,
self._config.logcat_params,
self.adb_logcat_file_path,
)
Expand All @@ -270,6 +276,7 @@ def _stop(self):
except Exception:
self._ad.log.exception('Failed to stop adb logcat.')
self._adb_logcat_process = None
self._last_connection_time = None

def pause(self):
"""Pauses logcat.
Expand All @@ -279,6 +286,12 @@ def pause(self):
some logs would be lost.
"""
self._stop()
try:
response = self._ad.adb.shell(['date', '-Is', r'+%Y-%m-%d\ %H:%M:%S.%N'])
if response:
self._last_connection_time = response.decode('utf-8').strip()
except adb.AdbError as e:
self._ad.log.exception('Failed to get host time.')

def resume(self):
"""Resumes a paused logcat service."""
Expand Down
161 changes: 157 additions & 4 deletions tests/mobly/controllers/android_device_lib/services/logcat_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -132,7 +132,7 @@ def test_start_and_stop(
'logcat,%s,fakemodel,123.txt' % ad.serial,
)
create_dir_mock.assert_called_with(os.path.dirname(expected_log_path))
adb_cmd = ' "adb" -s %s logcat -v threadtime -T 1 >> %s'
adb_cmd = ' "adb" -s %s logcat -v threadtime -T "1" >> %s'
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)
Expand Down Expand Up @@ -206,7 +206,8 @@ def test_update_config(
self.assertTrue(logcat_service._adb_logcat_process)
create_dir_mock.assert_has_calls([mock.call('some/path')])
expected_adb_cmd = (
' "adb" -s 1 logcat -v threadtime -T 1 -a -b -c >> "some/path/log.txt" '
' "adb" -s 1 logcat -v threadtime -T "1" -a -b -c >>'
' "some/path/log.txt" '
)
start_proc_mock.assert_called_with(expected_adb_cmd, shell=True)
self.assertEqual(logcat_service.adb_logcat_file_path, 'some/path/log.txt')
Expand Down Expand Up @@ -264,8 +265,118 @@ def test_update_config_while_running(
'mobly.controllers.android_device_lib.services.logcat.Logcat.clear_adb_log',
return_value=mock_android_device.MockAdbProxy('1'),
)
@mock.patch('mobly.logger.get_log_file_timestamp')
def test_pause_and_resume(
self,
get_timestamp_mock,
clear_adb_mock,
open_logcat_mock,
stop_proc_mock,
start_proc_mock,
create_dir_mock,
FastbootProxy,
MockAdbProxy,
):
# The test will pause and resume the log collection twice. The
# resume operation is supposed to request the log messages since the
# log collection got paused.

DATE_COMMAND = ['date', '-Is', r'+%Y-%m-%d\ %H:%M:%S.%N']
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@xpconanfan xpconanfan Jan 24, 2026

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I didn't expect to see so much change in the existing test.
is it possible to simplify the logic here?

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@xr-gh xr-gh Jan 26, 2026

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I added comments around the code, but I feel this is as simple as it gets, not sure how to simplify this any further.

DATE_RESULT_FIRST_PAUSE = '2026-01-14 17:01:02.342'
DATE_RESULT_SECOND_PAUSE = '2026-01-14 17:03:04.789'
state = {'date_result' : ''}

adb_instance = MockAdbProxy.return_value
adb_instance.shell = mock.MagicMock()
adb_instance.has_shell_command = mock.MagicMock(return_value=True)

def adb_shell_logic(cmd, *args, **kwargs):
if cmd == DATE_COMMAND:
return state['date_result'].encode('utf-8')
return b'' # Use empty bytes to match ADB's typical return type
adb_instance.shell.side_effect = adb_shell_logic

# Set up the logcat instance.
mock_serial = '1'
ad = android_device.AndroidDevice(serial=mock_serial)
get_timestamp_mock.return_value = '123'
configs = logcat.Config(clear_log=True)
logcat_service = logcat.Logcat(ad, configs)
logcat_service.start()
expected_log_path = os.path.join(
logging.log_path,
'AndroidDevice%s' % ad.serial,
'logcat,%s,fakemodel,123.txt' % ad.serial,
)

# We expect that the first logcat invocation happens with time "1"
# to include all previously generated log messages.
adb_cmd = ' "adb" -s %s logcat -v threadtime -T "1" >> %s'
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)

clear_adb_mock.assert_called_once_with()
self.assertTrue(logcat_service.is_alive)

def pause_logcat_service_resume_logcat_service(date):
# Pause the log collection and then resume the log collection.
#
# The passed in `date` is what we expect to receive as an argument
# to the `logcat -T` argument when the logcat serice gets resumed.
# The `date` argument corresponds to the time stamp when the log
# collection got stopped, and we expect that we look back to that
# time stamp when we resume the log collection.

# Pause the logcat collection at time stamp `date`.
state['date_result'] = date
logcat_service.pause()
self.assertFalse(logcat_service.is_alive)
stop_proc_mock.assert_called_with('process')
self.assertIsNone(logcat_service._adb_logcat_process)
clear_adb_mock.reset_mock()

# Resume the logcat collection, which should look back to time
# stamp `date`.
logcat_service.resume()
self.assertTrue(logcat_service.is_alive)
clear_adb_mock.assert_not_called()
adb_cmd = (
' "adb" -s %s logcat -v threadtime -T "' + date + '" >> %s'
)
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)

# First pause / resume iteration
pause_logcat_service_resume_logcat_service(DATE_RESULT_FIRST_PAUSE)
# self.assertEqual(adb_instance.shell.call_count, 1)

# Second pause / resume iteration
pause_logcat_service_resume_logcat_service(DATE_RESULT_SECOND_PAUSE)

logcat_service.stop()

@mock.patch(
'mobly.controllers.android_device_lib.adb.AdbProxy',
return_value=mock_android_device.MockAdbProxy('1'),
)
@mock.patch(
'mobly.controllers.android_device_lib.fastboot.FastbootProxy',
return_value=mock_android_device.MockFastbootProxy('1'),
)
@mock.patch('mobly.utils.create_dir')
@mock.patch('mobly.utils.start_standing_subprocess', return_value='process')
@mock.patch('mobly.utils.stop_standing_subprocess')
@mock.patch.object(logcat.Logcat, '_open_logcat_file')
@mock.patch(
'mobly.controllers.android_device_lib.services.logcat.Logcat.clear_adb_log',
return_value=mock_android_device.MockAdbProxy('1'),
)
@mock.patch('mobly.logger.get_log_file_timestamp')
def test_pause_and_resume_while_raising_exception_when_getting_pause_time(
self,
get_timestamp_mock,
clear_adb_mock,
open_logcat_mock,
stop_proc_mock,
Expand All @@ -274,20 +385,62 @@ def test_pause_and_resume(
FastbootProxy,
MockAdbProxy,
):
# The test will pause and resume the log collection, but it will
# fail to retrieve a date while pausing the log collection. The log
# collection is expected to resume back from the earliest time stamp
# "1".

DATE_COMMAND = ['date', '-Is', r'+%Y-%m-%d\ %H:%M:%S.%N']

adb_instance = MockAdbProxy.return_value
adb_instance.shell = mock.MagicMock()
adb_instance.has_shell_command = mock.MagicMock(return_value=True)

def adb_shell_logic(cmd, *args, **kwargs):
if cmd == DATE_COMMAND:
raise adb.AdbError(cmd, b'', b'Device is disconnected', 1)
return b'' # Use empty bytes to match ADB's typical return type
adb_instance.shell.side_effect = adb_shell_logic

# Set up the logcat instance.
mock_serial = '1'
ad = android_device.AndroidDevice(serial=mock_serial)
logcat_service = logcat.Logcat(ad, logcat.Config(clear_log=True))
get_timestamp_mock.return_value = '123'
configs = logcat.Config(clear_log=True)
logcat_service = logcat.Logcat(ad, configs)
logcat_service.start()
expected_log_path = os.path.join(
logging.log_path,
'AndroidDevice%s' % ad.serial,
'logcat,%s,fakemodel,123.txt' % ad.serial,
)

# We expect that the first logcat invocation happens with time "1"
# to include all previously generated log messages.
adb_cmd = ' "adb" -s %s logcat -v threadtime -T "1" >> %s'
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)

clear_adb_mock.assert_called_once_with()
self.assertTrue(logcat_service.is_alive)

# Pause should fail to retrieve a valid date
logcat_service.pause()
self.assertFalse(logcat_service.is_alive)
stop_proc_mock.assert_called_with('process')
self.assertIsNone(logcat_service._adb_logcat_process)
clear_adb_mock.reset_mock()

# Resume should start with the first logcat message again
logcat_service.resume()
self.assertTrue(logcat_service.is_alive)
clear_adb_mock.assert_not_called()
adb_cmd = ' "adb" -s %s logcat -v threadtime -T "1" >> %s'
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)

logcat_service.stop()

@mock.patch(
Expand Down Expand Up @@ -422,7 +575,7 @@ def test_take_logcat_with_extra_params(
'logcat,%s,fakemodel,123.txt' % ad.serial,
)
create_dir_mock.assert_called_with(os.path.dirname(expected_log_path))
adb_cmd = ' "adb" -s %s logcat -v threadtime -T 1 -b radio >> %s'
adb_cmd = ' "adb" -s %s logcat -v threadtime -T "1" -b radio >> %s'
start_proc_mock.assert_called_with(
adb_cmd % (ad.serial, '"%s" ' % expected_log_path), shell=True
)
Expand Down
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