There are several cases that we cover already:

• Currently we have this module:

  cpython/Lib/test/test_lazy_import/data/module_with_getattr.py

  Lines 1 to 4 in 0ed497a

  	def __getattr__(name):
  	if name == "dynamic_attr":
  	return "from_getattr"
  	raise AttributeError(name)

• And this package

  cpython/Lib/test/test_lazy_import/data/pkg/__init__.py

  Lines 1 to 6 in 0ed497a

  	x = 42
  	def __getattr__(name):
  	if name == "dynamic_attr":
  	return "from_getattr"
  	raise AttributeError(name)

That have __getattr__ functions defined on a module level.
We test that here:

• Module:

  cpython/Lib/test/test_lazy_import/__init__.py

  Lines 91 to 109 in 0ed497a

  	@support.requires_subprocess()
  	def test_from_import_with_module_getattr(self):
  	"""Lazy from import should respect module-level __getattr__."""
  	code = textwrap.dedent("""
  	lazy from test.test_lazy_import.data.module_with_getattr import dynamic_attr
  	assert dynamic_attr == "from_getattr"
  	""")
  	assert_python_ok("-c", code)
  	@support.requires_subprocess()
  	def test_from_import_with_imported_module_getattr(self):
  	"""Lazy from import should not shadow an imported module's __getattr__."""
  	code = textwrap.dedent("""
  	import test.test_lazy_import.data.module_with_getattr as mod
  	lazy from test.test_lazy_import.data.module_with_getattr import dynamic_attr
  	assert dynamic_attr == "from_getattr"
  	assert mod.dynamic_attr == "from_getattr"
  	""")
  	assert_python_ok("-c", code)

• Package:

  cpython/Lib/test/test_lazy_import/__init__.py

  Lines 461 to 470 in 0ed497a

  	@support.requires_subprocess()
  	def test_package_from_import_with_module_getattr(self):
  	"""Lazy from import should respect a package's __getattr__."""
  	code = textwrap.dedent("""
  	import test.test_lazy_import.data.pkg as pkg
  	lazy from test.test_lazy_import.data.pkg import dynamic_attr
  	assert dynamic_attr == "from_getattr"
  	assert pkg.dynamic_attr == "from_getattr"
  	""")
  	assert_python_ok("-c", code)

What do we never test?

1. Raising ImportError directly in __getattr__
2. Calling AttributeError in __getattr__, now all names do exist and are just returned
3. Raising some different error
4. Raising a warning

These are all realistic cases that should be covered.
I have a PR ready.

Linked PRs

• gh-149981: Test lazy import corner cases with module-level __getattr__ #149982