Reintroduce test_has_names

This just tests which names exist without checking anything else. It also
doesn't use hypothesis, so it should work even if the library doesn't have
proper hypothesis support (assuming the test suite can even run at all in that
case, I'm not completely sure).

Author: asmeurer

array_api_tests/stubs.py

@@ -34,6 +34,10 @@
     f for n, f in inspect.getmembers(array, predicate=inspect.isfunction)
     if n != "__init__"  # probably exists for Sphinx
 ]
+array_attributes = [
+    n for n, f in inspect.getmembers(array, predicate=lambda x: not inspect.isfunction(x))
+    if n != "__init__"  # probably exists for Sphinx
+]
 
 category_to_funcs: Dict[str, List[FunctionType]] = {}
 for name, mod in name_to_mod.items():

array_api_tests/test_signatures.py

@@ -32,9 +32,9 @@ def squeeze(x, /, axis):
 from . import dtype_helpers as dh
 from . import hypothesis_helpers as hh
 from . import xps
-from ._array_module import _UndefinedStub
-from ._array_module import mod as xp
-from .stubs import array_methods, category_to_funcs, extension_to_funcs
+from ._array_module import _UndefinedStub, mod as xp, mod_name
+from .stubs import (array_attributes, array_methods, category_to_funcs,
+                    extension_to_funcs, EXTENSIONS)
 from .typing import Array, DataType
 
 pytestmark = pytest.mark.ci
@@ -252,3 +252,32 @@ def test_array_method_signature(stub: FunctionType, data: DataObject):
     assert hasattr(x, stub.__name__), f"{stub.__name__} not found in array object {x!r}"
     method = getattr(x, stub.__name__)
     _test_func_signature(method, stub, array=x)
+
+has_name_params = []
+for ext, stubs in extension_to_funcs.items():
+    for stub in stubs:
+        has_name_params.append(pytest.param(ext, stub.__name__))
+for cat, stubs in category_to_funcs.items():
+    for stub in stubs:
+        has_name_params.append(pytest.param(cat, stub.__name__))
+for meth in array_methods:
+    has_name_params.append(pytest.param('array_method', meth.__name__))
+for attr in array_attributes:
+    has_name_params.append(pytest.param('array_attribute', attr))
+
+# This is a very basic test to see what names are defined in a library. It
+# does not even require functioning hypothesis array_api support.
+@pytest.mark.parametrize("category, name", has_name_params)
+def test_has_names(category, name):
+    if category in EXTENSIONS:
+        ext_mod = getattr(xp, category)
+        assert hasattr(ext_mod, name), f"{mod_name} is missing the {category} extension function {name}()"
+    elif category.startswith('array_'):
+        # TODO: This would fail if ones() is missing.
+        arr = xp.ones((1, 1))
+        if category == 'array_attribute':
+            assert hasattr(arr, name), f"The {mod_name} array object is missing the attribute {name}"
+        else:
+            assert hasattr(arr, name), f"The {mod_name} array object is missing the method {name}()"
+    else:
+        assert hasattr(xp, name), f"{mod_name} is missing the {category} function {name}()"