kunit: tool: fix newly introduced typechecker errors

After upgrading mypy and pytype from pip, we see 2 new errors when
running ./tools/testing/kunit/run_checks.py.

Error #1: mypy and pytype
They now deduce that importlib.util.spec_from_file_location() can return
None and note that we're not checking for this.

We validate that the arch is valid (i.e. the file exists) beforehand.
Add in an `asssert spec is not None` to appease the checkers.

Error #2: pytype bug https://github.com/google/pytype/issues/1057
It doesn't like `from datetime import datetime`, specifically that a
type shares a name with a module.

We can workaround this by either
* renaming the import or just using `import datetime`
* passing the new `--fix-module-collisions` flag to pytype.

We pick the first option for now because
* the flag is quite new, only in the 2021.11.29 release.
* I'd prefer if people can just run `pytype <file>`
Signed-off-by: NDaniel Latypov <dlatypov@google.com>
Reviewed-by: NBrendan Higgins <brendanhiggins@google.com>
Signed-off-by: NShuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit_kernel.py

@@ -209,6 +209,7 @@ def get_source_tree_ops_from_qemu_config(config_path: str,
 	# exists as a file.
 	module_path = '.' + os.path.join(os.path.basename(QEMU_CONFIGS_DIR), os.path.basename(config_path))
 	spec = importlib.util.spec_from_file_location(module_path, config_path)
+	assert spec is not None
 	config = importlib.util.module_from_spec(spec)
 	# See https://github.com/python/typeshed/pull/2626 for context.
 	assert isinstance(spec.loader, importlib.abc.Loader)

tools/testing/kunit/kunit_parser.py

@@ -12,7 +12,7 @@
 from __future__ import annotations
 import re
 
-from datetime import datetime
+import datetime
 from enum import Enum, auto
 from functools import reduce
 from typing import Iterable, Iterator, List, Optional, Tuple
@@ -517,7 +517,7 @@ ANSI_LEN = len(red(''))
 
 def print_with_timestamp(message: str) -> None:
 	"""Prints message with timestamp at beginning."""
-	print('[%s] %s' % (datetime.now().strftime('%H:%M:%S'), message))
+	print('[%s] %s' % (datetime.datetime.now().strftime('%H:%M:%S'), message))
 
 def format_test_divider(message: str, len_message: int) -> str:
 	"""