Remove unused imports and fix some other linter errors.

recipe_engine/simulation_test.py

 # Copyright 2014 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Provides simulator test coverage for individual recipes."""
 
 import StringIO
-import ast
-import contextlib
 import copy
 import json
 import logging
 import os
 import re
 import sys
-import textwrap
-import traceback
-import inspect
 
-from collections import OrderedDict, namedtuple
+from . import env
 
 from . import config_types
-from . import env
 from . import loader
 from . import run
 from . import step_runner
 from . import stream
-from expect_tests.util import covers as expect_tests_covers

[Vadim Sh., 2017/02/21 05:46:26]

I hope it isn't some magical import that enables something by being imported?

[iannucci, 2017/02/21 06:07:47]

Shouldn't be...

 from expect_tests.main import main as expect_tests_main
 from expect_tests.type_definitions import Result, Test, FuncCall
 from .checker import Checker, VerifySubset
 from google.protobuf import json_format as jsonpb
 
 # These variables must be set in the dynamic scope of the functions in this
 # file.  We do this instead of passing because the threading system of expect
 # tests doesn't know how to serialize it.
 _UNIVERSE_VIEW = None
 _ENGINE_FLAGS = None
@@ skipping 201 matching lines @@
       logging.warn("Ignoring %s environment variable." % env_var)
       os.environ.pop(env_var)
 
   global _UNIVERSE_VIEW
   _UNIVERSE_VIEW = universe_view
   global _ENGINE_FLAGS
   _ENGINE_FLAGS = engine_flags
 
   expect_tests_main('recipe_simulation_test', GenerateTests,
                     cover_omit=cover_omit(), args=args)