ENH: allow importlib.LazyLoader to work with numpy and add test of th…

…is (#22045)

numpy/core/__init__.py

@@ -75,8 +75,10 @@
 from . import fromnumeric
 from .fromnumeric import *
 from . import defchararray as char
+from . import records
 from . import records as rec
 from .records import record, recarray, format_parser
+# Note: module name memmap is overwritten by a class with same name
 from .memmap import *
 from .defchararray import chararray
 from . import function_base

numpy/lib/__init__.py

@@ -21,6 +21,24 @@
 from . import scimath as emath
 
 # Private submodules
+# load module names. See https://github.com/networkx/networkx/issues/5838
+from . import type_check
+from . import index_tricks
+from . import function_base
+from . import nanfunctions
+from . import shape_base
+from . import stride_tricks
+from . import twodim_base
+from . import ufunclike
+from . import histograms
+from . import polynomial
+from . import utils
+from . import arraysetops
+from . import npyio
+from . import arrayterator
+from . import arraypad
+from . import _version
+
 from .type_check import *
 from .index_tricks import *
 from .function_base import *

numpy/matrixlib/__init__.py

@@ -1,6 +1,7 @@
 """Sub-package containing the matrix class and related functions.
 
 """
+from . import defmatrix
 from .defmatrix import *
 
 __all__ = defmatrix.__all__

numpy/testing/__init__.py

@@ -7,6 +7,7 @@
 """
 from unittest import TestCase
 
+from . import _private
 from ._private.utils import *
 from ._private.utils import (_assert_valid_refcount, _gen_alignment_data)
 from ._private import extbuild, decorators as dec

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)