TST: Test that numpy.typing can be imported in the the absence of typing-extensions

Author: BvB93

numpy/typing/tests/test_typing_extensions.py

@@ -0,0 +1,56 @@
+"""Tests for the optional typing-extensions dependency."""
+
+import sys
+import types
+import inspect
+import importlib
+
+import typing_extensions
+import numpy.typing as npt
+
+
+def _is_sub_module(obj: object) -> bool:
+    """Check if `obj` is a `numpy.typing` submodule."""
+    return inspect.ismodule(obj) and obj.__name__.startswith("numpy.typing")
+
+
+def _is_dunder(name: str) -> bool:
+    """Check whether `name` is a dunder."""
+    return name.startswith("__") and name.endswith("__")
+
+
+def _clear_attr(module: types.ModuleType) -> None:
+    """Clear all (non-dunder) module-level attributes."""
+    del_names = [name for name in vars(module) if not _is_dunder(name)]
+    for name in del_names:
+        delattr(module, name)
+
+
+MODULES = {"numpy.typing": npt}
+MODULES.update({
+    f"numpy.typing.{k}": v for k, v in vars(npt).items() if _is_sub_module(v)
+})
+
+
+def test_no_typing_extensions() -> None:
+    """Import `numpy.typing` in the absence of typing-extensions.
+
+    Notes
+    -----
+    Ideally, we'd just run the normal typing tests in an environment where
+    typing-extensions is not installed, but unfortunatelly this is currently
+    impossible as it is an indirect hard dependency of pytest.
+
+    """
+    assert "typing_extensions" in sys.modules
+
+    try:
+        sys.modules["typing_extensions"] = None
+        for name, module in MODULES.items():
+            _clear_attr(module)
+            assert importlib.reload(module), name
+    finally:
+        sys.modules["typing_extensions"] = typing_extensions
+        for module in MODULES.values():
+            _clear_attr(module)
+            importlib.reload(module)