Hide warning output when running specs

[faultyserver]

Parser warnings that come up from various specs have been appearing in the output for a while now. I think they used to be hidden by a MYST_ENV variable being set to test, but that isn't happening anymore.

The proper solution for this is to use interpret_with_mocked_output for these specs so that the output is captured and can be tested properly (right now the specs just check if a warning was raised, not what that warning was).

Most of the offending specs are probably using the it_warns helper method defined here:

myst/spec/support/interpret.cr

Lines 76 to 83 in d501552

	def it_warns(source, expected, file=__FILE__, line=__LINE__, end_line=__END_LINE__)
	it "raises warning from `#{source}`", file, line, end_line do
	interpreter=Interpreter.new
	program = parse_program(source)
	interpreter.run(program)
	interpreter.warnings.should eq expected
	end
	end

The fix would be to call interpret_with_mocked_output(source) from this method instead of creating a new Interpreter and running it directly, then checking the warnings from the interpreter object returned by that method.

[faultyserver]

It actually looks like these messages are coming from vm_spec.cr where it's testing the standard IO usage. I'm not sure what the best approach to solving this is.

[Jens0512]

What makes you think it comes from vm_spec.cr? Code containing underscore vars is not run in the VM specs. And we really should rename VM 😅 ... I clearly remember dealing with just this issue before, I might have forgotten to push it here though, or I i did, and it somehow got broken.

[faultyserver]

Well, I commented out everything in vm_spec because a test was failing (I had made some radical changes at the time) and the warning output didn't appear.

I think this is the offending line:

myst/src/myst/vm.cr

Line 15 in d501552

ENV["MYST_ENV"] = product? ? "prod" : "test"

It assigns the ENV variable, which will persist for the duration of the test suite. So even if the tests that actually output warnings to the terminal are in another file, this should be addressed to avoid leaking.

I think the best solution would be to remove that line entirely. The VM shouldn't be responsible for managing environment variables.