fix tests for stand-alone example scripts (#3605)

* add test that fails when there are no examples detected

* use rglob instead of glob to find example scripts

* changelog

Author: d-v-b

changes/3605.misc.md

@@ -0,0 +1 @@
+Fix a bug in the test suite that prevented stand-alone example scripts from being tested.

tests/test_examples.py

@@ -11,7 +11,7 @@
 from packaging.requirements import Requirement
 
 examples_dir = "examples"
-script_paths = Path(examples_dir).glob("*.py")
+script_paths = tuple(Path(examples_dir).rglob("*.py"))
 
 PEP_723_REGEX: Final = r"(?m)^# /// (?P<type>[a-zA-Z0-9-]+)$\s(?P<content>(^#(| .*)$\s)+)^# ///$"
 
@@ -62,6 +62,13 @@ def resave_script(source_path: Path, dest_path: Path) -> None:
     dest_path.write_text(dest_text)
 
 
+def test_script_paths() -> None:
+    """
+    Test that our test fixture is working properly and collecting script paths.
+    """
+    assert len(script_paths) > 0
+
+
 @pytest.mark.skipif(
     sys.platform in ("win32",), reason="This test fails due for unknown reasons on Windows in CI."
 )