str/Path mixup in TerminalReporter

[chebee7i]

I ran into this while tracking down another issue.

In TerminalReporter.pytest_runtest_logstart, we have:

pytest/src/_pytest/terminal.py

Lines 507 to 513 in adc1974

	def pytest_runtest_logstart(
	self, nodeid: str, location: Tuple[str, Optional[int], str]
	) -> None:
	# Ensure that the path is printed before the
	# 1st test of a module starts running.
	if self.showlongtestinfo:
	line = self._locationline(nodeid, *location)

where the first argument of location is expected to be a string. But the func signature and impl of _locationline and pathlib.bestrelpath are actually expecting a Path object:

pytest/src/_pytest/terminal.py

Lines 867 to 884 in adc1974

	def _locationline(self, nodeid, fspath, lineno, domain):
	def mkrel(nodeid):
	line = self.config.cwd_relative_nodeid(nodeid)
	if domain and line.endswith(domain):
	line = line[: -len(domain)]
	values = domain.split("[")
	values[0] = values[0].replace(".", "::") # don't replace '.' in params
	line += "[".join(values)
	return line
	# collect_fspath comes from testid which has a "/"-normalized path.
	if fspath:
	res = mkrel(nodeid)
	if self.verbosity >= 2 and nodeid.split("::")[0] != fspath.replace(
	"\\", nodes.SEP
	):
	res += " <- " + bestrelpath(self.startpath, fspath)

pytest/src/_pytest/pathlib.py

Lines 680 to 698 in adc1974

	def bestrelpath(directory: Path, dest: Path) -> str:
	"""Return a string which is a relative path from directory to dest such
	that directory/bestrelpath == dest.
	The paths must be either both absolute or both relative.
	If no such path can be determined, returns dest.
	"""
	if dest == directory:
	return os.curdir
	# Find the longest common directory.
	base = commonpath(directory, dest)
	# Can be the case on Windows for two absolute paths on different drives.
	# Can be the case for two relative paths without common prefix.
	# Can be the case for a relative path and an absolute path.
	if not base:
	return str(dest)
	reldirectory = directory.relative_to(base)
	reldest = dest.relative_to(base)

Due to the __tracebackhide__ = True line, this caused a harder-to-trackdown exception:

AttributeError: 'str' object has no attribute 'relative_to'

Apologies that I don't have a simple reproducible example (the code that generates this is a bit involved, bringing in twisted etc).
I experienced this when my report had location attribute that was of the following form: (str, int, str) right before calling: session.ihook.pytest_runtest_logreport(report=report) in Python 3.8.6 with pytest 3.6.4 (and the code snippets above are from master, so I know the issue still exists). The situation was that nodeid.split("::")[0] != fspath.replace("\\", nodes.SEP), so we needed to call bestrelpath which requires a Path object.

[hp310780]

Hi! Could I possibly take this on please if it's not already been resolved?

I thought maybe self.startpath could be assigned to a new Path type variable to be used when calling bestrelpath. Is that really naïve or something to go ahead and implement? Thanks for any advice!

[bluetech]

@hp310780 Definitely! Here's how I recommend approaching this:

• It looks like the problem is not detected by mypy because we are missing type annotations for _locationline. I'd start by adding those, and seeing that mypy complains.
• I'll also try to add a regression test which triggers the problem and verifying that it fails.
• Then you can try your suggested fix and see if it fixes mypy and the test.

Let us know if you have any questions.