Integration tests don't run on Windows

[jorisroovers]

The integration tests don't run on windows since they depend on sh.

To run the tests (without ./run_tests.sh which is a bash script):

pytest -rw -s qa/

To fix this, we should implement the same sh mock library that in the integration tests that we did for the main gitlint codebase.

[jorisroovers]

c889121 partially solves the dependency on sh, but I still need to implement a solution for the std I/O interaction functions that are used in various places of the integration tests. Example:

gitlint/qa/test_hooks.py

Lines 43 to 49 in 6cf5cc6

	def _interact(self, line, stdin):
	self.githook_output.append(line)
	# Answer 'yes' to question to keep violating commit-msg
	if "Your commit message contains the above violations" in line:
	response = self.responses[self.response_index]
	stdin.put("{0}\n".format(response))
	self.response_index = (self.response_index + 1) % len(self.responses)

sh allows you to pass these via the out argument which is useful and intuitive.

Also, when running the integration tests on Windows 10 (Python 3.7), I'm encountering UnicodeDecodeErrors, so there will be more work related to that as well.

We'll get there - just might take a while :-)

[jorisroovers]

Fixed a bunch of tests in #392.

Still failing:

• The hook tests, but that's expected since they still depend on the sh library. These tests also still fail when running the integration tests on linux without sh. I intent to look into fixing this soonish (as part of 0.19.0 release iteration).
• About a half dozen other tests. What's interesting is that some of these seem to pass on GHA but fail locally on windows. More investigation needed for these

qa/test_commits.py::CommitsTests::test_lint_staged_stdin FAILED 
qa/test_gitlint.py::IntegrationTests::test_git_empty_repo_staged FAILED # passes on CI?
qa/test_stdin.py::StdInTests::test_stdin_file FAILED
qa/test_stdin.py::StdInTests::test_stdin_pipe FAILED # passes on CI
qa/test_stdin.py::StdInTests::test_stdin_pipe_empty FAILED

Regardless, this is good progress since we can now run integration tests on windows on part of CI, something we've never done before.