Add unit tests for TempDir

#  Copyright 2022 Dominik Sekotill <dom.sekotill@kodo.org.uk>

#

#  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.

"""

Tests for the project_templates.resources module

"""

import atexit

import tempfile

import unittest

from pathlib import Path

from unittest.mock import Mock

from unittest.mock import patch

from project_templates import resources

TEMP_DIR = Path(tempfile.mkdtemp())

TEMP_DIR.joinpath("test-file").touch()

atexit.register(TEMP_DIR.rmdir)

atexit.register(TEMP_DIR.joinpath("test-file").unlink)

@patch("pathlib.Path.unlink")

@patch("pathlib.Path.rmdir")

@patch("tempfile.mkdtemp", return_value=TEMP_DIR.as_posix())

class TempDirTests(unittest.TestCase):

	"""

	Tests for the TempDir class

	"""

	def test_create(self, mkdtemp: Mock, rmdir: Mock, unlink: Mock) -> None:

		"""

		Check that a temporary directory is created safely and destroyed

		"""

		with self.subTest("create"):

			temp = resources.TempDir()

			mkdtemp.assert_called()

		with self.subTest("destroy"):

			temp.cleanup()

			rmdir.assert_called()

			unlink.assert_called()

	def test_context(self, mkdtemp: Mock, rmdir: Mock, unlink: Mock) -> None:

		"""

		Check use as a context manager

		"""

		with resources.TempDir():

			pass

		mkdtemp.assert_called()

		rmdir.assert_called()

		unlink.assert_called()

	def test_idempotent_cleanup(self, mkdtemp: Mock, rmdir: Mock, unlink: Mock) -> None:

		"""

		Check that calling cleanup after the directory has been removed causes no problems

		"""

		temp = resources.TempDir()

		with patch("pathlib.Path.exists", return_value=False):

			temp.cleanup()

		rmdir.assert_not_called()

		unlink.assert_not_called()

	def test_fail_safe(self, mkdtemp: Mock, rmdir: Mock, unlink: Mock) -> None:

		"""

		If an instance points at a non-temporary location, check nothing is damaged

		In the event that a TempDir is accidentally created pointing to a path not in the

		directory pointed to by `tempfile.gettempdir`, the class should safely refuse to

		clean up, to avoid damaging non-temporary files.

		"""

		mkdtemp.return_value = "/some-other/path"

		temp = resources.TempDir()

		with self.assertRaises(RuntimeError):

			temp.cleanup()

		rmdir.assert_not_called()

		unlink.assert_not_called()