Remove tests.lib.path

[pradyunsg]

File: https://github.com/pypa/pip/blob/master/tests/lib/path.py

There exist better alternatives to rolling out our own "Path" class for file handling -- the stdlib pathlib.Path and pathlib2.Path (backport to Py2) should be more than sufficient to satisfy our needs now.

if sys.python_version_info[0] >= 3:
    from pathlib import Path
else:
    from pathlib2 import Path

To be done:

• Confirm that the pathlib equivalent is indeed enough for our needs.
  • Figure out the relevant workarounds if needed.
• Drop this file and just directly perform the imports.

[chrahunt]

A few issues:

1. pathlib2 appears to have an issue on Windows with unicode filenames (Unusable on Windows/Python2.7 with unicode paths jazzband/pathlib2#56) which may need to be worked around.
2. tests.lib.path.Path inheriting from str/unicode will require the most effort to overcome. We will also end up needing something like to_fs_path_type(path) in a lot of tests for Python 2 compatibility.
3. PipTestEnvironment sets its *_path members to Path objects, but the base class expects objects that it can pass to os.path.* APIs
4. For a result = script.run('example', 'command') (PipTestResult), we do a lot of path in result.files_created and path not in result.files_created (in

   pip/tests/functional/test_download.py

   Line 24 in 449d268

   assert Path('scratch') / 'pip_downloads' / 'INITools-0.1.tar.gz' \

   for example). The not in case is very prone to error since it would pass unexpectedly if we forget to convert the Path object to a string. We could have a dedicated method, PipTestResult.created_file(path), for checking, but need to remember to always use it.

Number 4 and similar issues with comparisons seem like they would be the biggest route for regressions to go unnoticed or invalid tests to be introduced in the future.

[chrahunt]

Here's a mapping from the current class to equivalent functionality in pathlib.Path or elsewhere:

Done	Current	New	Note	PR
	+		deferred
✔️	abspath	resolve()	abspath	#7156
✔️	-	os.path.relpath()		#7151
✔️	/	/	no change
✔️	//		unused, removed	#6665
✔️	normpath	os.path.normpath()	normpath	#6747
✔️	rmtree()	shutil.rmtree()		#6742
✔️	copy()	shutil.copy()		#6746
✔️	copytree()	shutil.copytree()		#6743
✔️	move()	shutil.move()		#6745
✔️	glob()	glob()	no change
✔️	name	name	no change
✔️	read_text()	read_text()	no change
✔️	rename()	rename()	no change
✔️	rmdir()	rmdir()	no change
✔️	makedirs()	mkdir(parents=True)		#6701
✔️	touch()	touch()	touch	#6700
✔️	exists	exists()		#6670
✔️	ext	suffix		#6670
✔️	folder	parent		#6670
✔️	join()	joinpath()		#6670
✔️	namebase	stem		#6670
✔️	realpath	resolve()		#6670
✔️	remove()	unlink()		#6670
✔️	rm()	unlink()		#6670
✔️	write()	write_text()		#6670
✔️	atime		unused, removed	#6665
✔️	ctime		unused, removed	#6665
✔️	mtime		unused, removed	#6665
✔️	noext		unused, removed	#6665
✔️	normcase		unused, removed	#6665
✔️	renames()		unused, removed	#6665
✔️	supports_unicode()		unused, removed	#6665
✔️	walk()		unused, removed	#6665
✔️	mkdir()	mkdir()	mkdir	#6888

• abspath: absolute() is undocumented (see bpo-29688) - resolve() is not equivalent since it resolves symlinks
  • @pradyunsg found that we can use resolve() for our use cases: Remove tests.lib.path #6050 (comment)
• normpath: the path itself removes spurious double-slashes and . but not .., only resolve() does it but it also resolves symlinks
• mkdir: needs exist_ok parameter instead of assuming it is OK, and should not return self
• touch: the current function takes a times parameter which is not in pathlib.Path but it is not used anywhere

[pradyunsg]

@chrahunt I took the liberty of updating your comment above with #6670 items being marked as merged and moving things around to be:

• all operators at top
• done items at end of "section" (operators + methods/attributes)
• each PR's items sorted by name

[pradyunsg]

the current function takes a times parameter which is not in pathlib.Path but it is not used anywhere

Filed #6700 for removing this.

[pradyunsg]

needs exist_ok parameter instead of assuming it is OK

This only needs to be added to tests that would fail on directly switching this behavior.

And, in those cases, I feel we should blanket-replace path.mkdir with assert path.exists() anyway.

[pradyunsg]

#6701 gets rid of makedirs. :)