ENH: allow importlib.LazyLoader to work with numpy and add test of this (#22045)

1 files changed, 38 insertions, 0 deletions

diff --git a/numpy/tests/test_lazyloading.py b/numpy/tests/test_lazyloading.py
new file mode 100644
index 000000000..f31a4eab7
--- /dev/null
+++ b/numpy/tests/test_lazyloading.py
@@ -0,0 +1,38 @@
+import sys
+import importlib
+from importlib.util import LazyLoader, find_spec, module_from_spec
+import pytest
+
+
+# Warning raised by _reload_guard() in numpy/__init__.py
+@pytest.mark.filterwarnings("ignore:The NumPy module was reloaded")
+def test_lazy_load():
+    # gh-22045. lazyload doesn't import submodule names into the namespace
+    # muck with sys.modules to test the importing system
+    old_numpy = sys.modules.pop("numpy")
+
+    numpy_modules = {}
+    for mod_name, mod in list(sys.modules.items()):
+        if mod_name[:6] == "numpy.":
+            numpy_modules[mod_name] = mod
+            sys.modules.pop(mod_name)
+
+    try:
+        # create lazy load of numpy as np
+        spec = find_spec("numpy")
+        module = module_from_spec(spec)
+        sys.modules["numpy"] = module
+        loader = LazyLoader(spec.loader)
+        loader.exec_module(module)
+        np = module
+
+        # test a subpackage import
+        from numpy.lib import recfunctions
+
+        # test triggering the import of the package
+        np.ndarray
+
+    finally:
+        if old_numpy:
+            sys.modules["numpy"] = old_numpy
+            sys.modules.update(numpy_modules)