Enable git trace2 event format logging.

Ways to enable logging:
1) Set git's trace2.eventtarget config variable to desired logging path
2) Specify path via --git_trace2_event_log option

A unique logfile name is generated per repo execution (based on the repo session-id).

Testing:
1) Verified git config 'trace2.eventtarget' and flag enable logging.
2) Verified version/start/end events are expected format:
  https://git-scm.com/docs/api-trace2#_event_format
3) Unit tests

Bug: https://crbug.com/gerrit/13706
Change-Id: I335eba68124055321c4149979bec36ac16ef81eb
Tested-by: Ian Kasprzak <iankaz@google.com>
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/292262
Reviewed-by: Mike Frysinger <vapier@google.com>
Reviewed-by: Jonathan Nieder <jrn@google.com>

1 files changed, 169 insertions, 0 deletions

diff --git a/tests/test_git_trace2_event_log.py b/tests/test_git_trace2_event_log.py
new file mode 100644
index 00000000..3905630f
--- /dev/null
+++ b/tests/test_git_trace2_event_log.py
@@ -0,0 +1,169 @@
+# Copyright (C) 2020 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Unittests for the git_trace2_event_log.py module."""
+
+import json
+import tempfile
+import unittest
+
+import git_trace2_event_log
+
+
+class EventLogTestCase(unittest.TestCase):
+  """TestCase for the EventLog module."""
+
+  PARENT_SID_KEY = 'GIT_TRACE2_PARENT_SID'
+  PARENT_SID_VALUE = 'parent_sid'
+  SELF_SID_REGEX = r'repo-\d+T\d+Z-.*'
+  FULL_SID_REGEX = r'^%s/%s' % (PARENT_SID_VALUE, SELF_SID_REGEX)
+
+  def setUp(self):
+    """Load the event_log module every time."""
+    self._event_log_module = None
+    # By default we initialize with the expected case where
+    # repo launches us (so GIT_TRACE2_PARENT_SID is set).
+    env = {
+        self.PARENT_SID_KEY: self.PARENT_SID_VALUE,
+    }
+    self._event_log_module = git_trace2_event_log.EventLog(env=env)
+    self._log_data = None
+
+  def verifyCommonKeys(self, log_entry, expected_event_name, full_sid=True):
+    """Helper function to verify common event log keys."""
+    self.assertIn('event', log_entry)
+    self.assertIn('sid', log_entry)
+    self.assertIn('thread', log_entry)
+    self.assertIn('time', log_entry)
+
+    # Do basic data format validation.
+    self.assertEqual(expected_event_name, log_entry['event'])
+    if full_sid:
+      self.assertRegex(log_entry['sid'], self.FULL_SID_REGEX)
+    else:
+      self.assertRegex(log_entry['sid'], self.SELF_SID_REGEX)
+    self.assertRegex(log_entry['time'], r'^\d+-\d+-\d+T\d+:\d+:\d+\.\d+Z$')
+
+  def readLog(self, log_path):
+    """Helper function to read log data into a list."""
+    log_data = []
+    with open(log_path, mode='rb') as f:
+      for line in f:
+        log_data.append(json.loads(line))
+    return log_data
+
+  def test_initial_state_with_parent_sid(self):
+    """Test initial state when 'GIT_TRACE2_PARENT_SID' is set by parent."""
+    self.assertRegex(self._event_log_module.full_sid, self.FULL_SID_REGEX)
+
+  def test_initial_state_no_parent_sid(self):
+    """Test initial state when 'GIT_TRACE2_PARENT_SID' is not set."""
+    # Setup an empty environment dict (no parent sid).
+    self._event_log_module = git_trace2_event_log.EventLog(env={})
+    self.assertRegex(self._event_log_module.full_sid, self.SELF_SID_REGEX)
+
+  def test_version_event(self):
+    """Test 'version' event data is valid.
+
+    Verify that the 'version' event is written even when no other
+    events are addded.
+
+    Expected event log:
+    <version event>
+    """
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    # A log with no added events should only have the version entry.
+    self.assertEqual(len(self._log_data), 1)
+    version_event = self._log_data[0]
+    self.verifyCommonKeys(version_event, expected_event_name='version')
+    # Check for 'version' event specific fields.
+    self.assertIn('evt', version_event)
+    self.assertIn('exe', version_event)
+
+  def test_start_event(self):
+    """Test and validate 'start' event data is valid.
+
+    Expected event log:
+    <version event>
+    <start event>
+    """
+    self._event_log_module.StartEvent()
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 2)
+    start_event = self._log_data[1]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+    self.verifyCommonKeys(start_event, expected_event_name='start')
+    # Check for 'start' event specific fields.
+    self.assertIn('argv', start_event)
+    self.assertTrue(isinstance(start_event['argv'], list))
+
+  def test_exit_event_result_none(self):
+    """Test 'exit' event data is valid when result is None.
+
+    We expect None result to be converted to 0 in the exit event data.
+
+    Expected event log:
+    <version event>
+    <exit event>
+    """
+    self._event_log_module.ExitEvent(None)
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 2)
+    exit_event = self._log_data[1]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+    self.verifyCommonKeys(exit_event, expected_event_name='exit')
+    # Check for 'exit' event specific fields.
+    self.assertIn('code', exit_event)
+    # 'None' result should convert to 0 (successful) return code.
+    self.assertEqual(exit_event['code'], 0)
+
+  def test_exit_event_result_integer(self):
+    """Test 'exit' event data is valid when result is an integer.
+
+    Expected event log:
+    <version event>
+    <exit event>
+    """
+    self._event_log_module.ExitEvent(2)
+    with tempfile.TemporaryDirectory(prefix='event_log_tests') as tempdir:
+      log_path = self._event_log_module.Write(path=tempdir)
+      self._log_data = self.readLog(log_path)
+
+    self.assertEqual(len(self._log_data), 2)
+    exit_event = self._log_data[1]
+    self.verifyCommonKeys(self._log_data[0], expected_event_name='version')
+    self.verifyCommonKeys(exit_event, expected_event_name='exit')
+    # Check for 'exit' event specific fields.
+    self.assertIn('code', exit_event)
+    self.assertEqual(exit_event['code'], 2)
+
+  # TODO(https://crbug.com/gerrit/13706): Add additional test coverage for
+  # Write() where:
+  # - path=None (using git config call)
+  # - path=<Non-String type> (raises TypeError)
+  # - path=<Non-Directory> (should return None)
+  # - tempfile.NamedTemporaryFile errors with FileExistsError (should return  None)
+
+
+if __name__ == '__main__':
+  unittest.main()