michael@0: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: 
michael@0: """Helper module for calling python-based tests."""
michael@0: 
michael@0: 
michael@0: import logging
michael@0: import sys
michael@0: import time
michael@0: 
michael@0: from test_result import TestResults
michael@0: 
michael@0: 
michael@0: def CallPythonTest(test, options):
michael@0:   """Invokes a test function and translates Python exceptions into test results.
michael@0: 
michael@0:   This method invokes SetUp()/TearDown() on the test. It is intended to be
michael@0:   resilient to exceptions in SetUp(), the test itself, and TearDown(). Any
michael@0:   Python exception means the test is marked as failed, and the test result will
michael@0:   contain information about the exception.
michael@0: 
michael@0:   If SetUp() raises an exception, the test is not run.
michael@0: 
michael@0:   If TearDown() raises an exception, the test is treated as a failure. However,
michael@0:   if the test itself raised an exception beforehand, that stack trace will take
michael@0:   precedence whether or not TearDown() also raised an exception.
michael@0: 
michael@0:   shard_index is not applicable in single-device scenarios, when test execution
michael@0:   is serial rather than parallel. Tests can use this to bring up servers with
michael@0:   unique port numbers, for example. See also python_test_sharder.
michael@0: 
michael@0:   Args:
michael@0:     test: an object which is ostensibly a subclass of PythonTestBase.
michael@0:     options: Options to use for setting up tests.
michael@0: 
michael@0:   Returns:
michael@0:     A TestResults object which contains any results produced by the test or, in
michael@0:     the case of a Python exception, the Python exception info.
michael@0:   """
michael@0: 
michael@0:   start_date_ms = int(time.time()) * 1000
michael@0:   failed = False
michael@0: 
michael@0:   try:
michael@0:     test.SetUp(options)
michael@0:   except Exception:
michael@0:     failed = True
michael@0:     logging.exception(
michael@0:         'Caught exception while trying to run SetUp() for test: ' +
michael@0:         test.qualified_name)
michael@0:     # Tests whose SetUp() method has failed are likely to fail, or at least
michael@0:     # yield invalid results.
michael@0:     exc_info = sys.exc_info()
michael@0:     return TestResults.FromPythonException(test.qualified_name, start_date_ms,
michael@0:                                            exc_info)
michael@0: 
michael@0:   try:
michael@0:     result = test.Run()
michael@0:   except Exception:
michael@0:     # Setting this lets TearDown() avoid stomping on our stack trace from Run()
michael@0:     # should TearDown() also raise an exception.
michael@0:     failed = True
michael@0:     logging.exception('Caught exception while trying to run test: ' +
michael@0:                       test.qualified_name)
michael@0:     exc_info = sys.exc_info()
michael@0:     result = TestResults.FromPythonException(test.qualified_name, start_date_ms,
michael@0:                                              exc_info)
michael@0: 
michael@0:   try:
michael@0:     test.TearDown()
michael@0:   except Exception:
michael@0:     logging.exception(
michael@0:         'Caught exception while trying run TearDown() for test: ' +
michael@0:         test.qualified_name)
michael@0:     if not failed:
michael@0:       # Don't stomp the error during the test if TearDown blows up. This is a
michael@0:       # trade-off: if the test fails, this will mask any problem with TearDown
michael@0:       # until the test is fixed.
michael@0:       exc_info = sys.exc_info()
michael@0:       result = TestResults.FromPythonException(test.qualified_name,
michael@0:                                                start_date_ms, exc_info)
michael@0: 
michael@0:   return result