`test_keywords` in `test_popen` can be improved

[sobolevn]

Bug report

test_keywords here:

cpython/Lib/test/test_popen.py

Lines 65 to 68 in 7fd6160

	def test_keywords(self):
	with os.popen(cmd="exit 0", mode="w", buffering=-1):
	pass

does not assert anything. I propose to use an example similar to this one:

cpython/Lib/test/test_popen.py

Lines 57 to 59 in 7fd6160

	def test_contextmanager(self):
	with os.popen("echo hello") as f:
	self.assertEqual(f.read(), "hello\n")

and at least assert that the expected program executed and that f is still not closed in with body.

I have a PR ready.

Linked PRs

• gh-131234: Improve test_popen with more asserts #131235
• [3.13] gh-131234: Improve test_popen with more asserts (GH-131235) #131240
• [3.12] gh-131234: Improve test_popen with more asserts (GH-131235) #131241