test_modulefinder always modifies execution environment

[tiran]

Bug report

test_modulefinder creates a temporary directory in its global module scope

cpython/Lib/test/test_modulefinder.py

Lines 13 to 14 in 22df2e0

	TEST_DIR = tempfile.mkdtemp()
	TEST_PATH = [TEST_DIR, os.path.dirname(tempfile.__file__)]

and removes the temporary directory in each test method

cpython/Lib/test/test_modulefinder.py

Lines 349 to 350 in 22df2e0

	finally:
	shutil.rmtree(TEST_DIR)

If the test is executed in an environment without test worker processes (e.g. WASI) then the test runner complains about changes to the execution environment:

/python-wasm/cpython/builddir/wasi# wasmtime run --mapdir .::../../ -- python.wasm -m test --fail-env-changed test_modulefinder
0:00:00 Run tests sequentially
0:00:00 [1/1] test_modulefinder
Warning -- files was modified by test_modulefinder
Warning -- Before: ['tmp8avdrxn0/']
Warning -- After: [] 
test_modulefinder failed (env changed)

== Tests result: ENV CHANGED ==

1 test altered the execution environment:
 test_modulefinder

Total duration: 292 ms
Tests result: ENV CHANGED

test_modulefinder should create the temporary directory in setUp and rmtree it in tearDown methods instead.