EDU-3510: Python: Added paragraph that warns about pytest.fixture(scope="session") with test server

[edmondop]

What does this PR do?

Addresses #3111 . When running tests in a project I noticed:

• Time skipping wasn't working even if it was enabled
• samples-python test never reuse the same workflow environment with timeskipping

This additional paragraph should warn developers familiar with pytest.fixtures not to use the scope session for caching the workflow environment

[fairlydurable]

Created SDK-2941 to review

[cretz]

It is a bit strange to have the primary code be the wrong code and have the same code correctly below (which you don't usually redefine the same function in the same code block). Maybe something like:

Suggested change

	# This might break because it will reuse the workflow environment
	pytest.fixture(scope="session")
	def workflow_environment():
	return WorkflowEnvironment.start_time_skipping()
	def test_1(workflow_environment):
	pass
	def test_2(workflow_environment):
	pass
	# Correct: if you don't specify a scope, the default scope is function,
	# so a new workflow environment will be created for each test
	@pytest.fixture
	def workflow_environment():
	return WorkflowEnvironment.start_time_skipping()
	# Notice how this doesn't specify a "scope" like "session" scope. If you don't
	# specify a scope, the default scope is function, so a new workflow
	# environment will be created for each test.
	@pytest.fixture
	def workflow_environment():
	return WorkflowEnvironment.start_time_skipping()
	def test_1(workflow_environment):
	pass
	def test_2(workflow_environment):
	pass

Or if you must have the incorrect way be the in the initial block, can you move the correct way into its own separate block? It's a bit confusing to see the same method defined twice in the same block.

[cretz]

Suggested change

	pytest.fixture(scope="session")
	@pytest.fixture(scope="session")

If you do keep this, need @

[cretz]

Suggested change

When using pytest fixtures to setup databases, application servers and common infrastructure it is not unusual to use the `session` scope to ensure the fixture is shared among multiple tests. However, with the test server it is important that each test is executed in isolation. Launching a test server per test introduce negligible overhead and ensures your test do not conflict with each other

When using pytest fixtures to setup databases, application servers and common infrastructure it is not unusual to use the `session` scope to ensure the fixture is shared among multiple tests. However, with the time-skipping test server it is important that each test is executed in isolation. Launching a test server per test introduce negligible overhead and ensures your test do not conflict with each other

Notice, this only applies to the time skipping test server, not the local test server where it is very normal to share it across tests.