Add Pep561 tests for stub-only package with namespace packages (#11141)

This only adds tests that show the current behavior when we provide a stub-only package for a subpackage of a namespace package

Proposals for behavior changes exist in python/typeshed#5800

Real world example is the `protobuf` package which installs to `google.protobuf` and the `types-protobuf` package which installs to `google-stubs/protobuf` (where `google` is a namespace package)

Author: nipunn1313

Diff for: mypy/test/testmodulefinder.py

@@ -184,6 +184,13 @@ def test__packages_with_ns(self) -> None:
             ("ns_pkg_untyped.b.c", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
             ("ns_pkg_untyped.a.a_var", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
 
+            # Namespace package without stub package
+            ("ns_pkg_w_stubs", self.path("ns_pkg_w_stubs")),
+            ("ns_pkg_w_stubs.typed", self.path("ns_pkg_w_stubs-stubs", "typed", "__init__.pyi")),
+            ("ns_pkg_w_stubs.typed_inline",
+                self.path("ns_pkg_w_stubs", "typed_inline", "__init__.py")),
+            ("ns_pkg_w_stubs.untyped", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
+
             # Regular package with py.typed
             ("pkg_typed", self.path("pkg_typed", "__init__.py")),
             ("pkg_typed.a", self.path("pkg_typed", "a.py")),
@@ -239,6 +246,13 @@ def test__packages_without_ns(self) -> None:
             ("ns_pkg_untyped.b.c", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
             ("ns_pkg_untyped.a.a_var", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
 
+            # Namespace package without stub package
+            ("ns_pkg_w_stubs", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
+            ("ns_pkg_w_stubs.typed", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
+            ("ns_pkg_w_stubs.typed_inline",
+                self.path("ns_pkg_w_stubs", "typed_inline", "__init__.py")),
+            ("ns_pkg_w_stubs.untyped", ModuleNotFoundReason.FOUND_WITHOUT_TYPE_HINTS),
+
             # Regular package with py.typed
             ("pkg_typed", self.path("pkg_typed", "__init__.py")),
             ("pkg_typed.a", self.path("pkg_typed", "a.py")),

Diff for: test-data/packages/typedpkg_ns/typedpkg_ns/ns/__init__.py renamed to test-data/packages/modulefinder-site-packages/ns_pkg_w_stubs-stubs/typed/__init__.pyi

@@ -1,10 +1,10 @@
-from setuptools import setup, find_packages
+from setuptools import setup
 
 setup(
     name='typedpkg_namespace.alpha',
     version='1.0.0',
-    packages=find_packages(),
     namespace_packages=['typedpkg_ns'],
     zip_safe=False,
-    package_data={'typedpkg_ns.ns': ['py.typed']}
+    package_data={'typedpkg_ns.a': ['py.typed']},
+    packages=['typedpkg_ns.a'],
 )

Diff for: test-data/packages/typedpkg_ns/typedpkg_ns/ns/py.typed renamed to test-data/packages/modulefinder-site-packages/ns_pkg_w_stubs/typed/__init__.py

@@ -0,0 +1,14 @@
+"""
+This setup file installs packages to test mypy's PEP 561 implementation
+"""
+
+from distutils.core import setup
+
+setup(
+    name='typedpkg_ns_b-stubs',
+    author="The mypy team",
+    version='0.1',
+    namespace_packages=['typedpkg_ns-stubs'],
+    package_data={'typedpkg_ns-stubs.b': ['__init__.pyi', 'bbb.pyi']},
+    packages=['typedpkg_ns-stubs.b'],
+)

Diff for: test-data/packages/modulefinder-site-packages/ns_pkg_w_stubs/typed_inline/__init__.py

@@ -0,0 +1 @@
+def bf(a: bool) -> bool: ...

Diff for: test-data/packages/modulefinder-site-packages/ns_pkg_w_stubs/typed_inline/py.typed

@@ -0,0 +1,10 @@
+from setuptools import setup
+
+setup(
+    name='typedpkg_namespace.beta',
+    version='1.0.0',
+    namespace_packages=['typedpkg_ns'],
+    zip_safe=False,
+    package_data={'typedpkg_ns.b': []},
+    packages=['typedpkg_ns.b'],
+)

Diff for: test-data/packages/modulefinder-site-packages/ns_pkg_w_stubs/untyped/__init__.py

@@ -0,0 +1,2 @@
+# namespace pkg
+__import__("pkg_resources").declare_namespace(__name__)

Diff for: test-data/packages/typedpkg_ns/setup.py renamed to test-data/packages/typedpkg_ns_a/setup.py

@@ -0,0 +1,2 @@
+def bf(a):
+    return not a

Diff for: test-data/packages/typedpkg_ns/typedpkg_ns/__init__.py renamed to test-data/packages/typedpkg_ns_a/typedpkg_ns/__init__.py

@@ -119,10 +119,10 @@ reveal_type(a)
 testTypedPkgSimpleEditableEgg.py:5: note: Revealed type is "builtins.tuple[builtins.str]"
 
 [case testTypedPkgNamespaceImportFrom]
-# pkgs: typedpkg, typedpkg_ns
+# pkgs: typedpkg, typedpkg_ns_a
 from typedpkg.pkg.aaa import af
-from typedpkg_ns.ns.bbb import bf
-from typedpkg_ns.ns.dne import dne
+from typedpkg_ns.a.bbb import bf
+from typedpkg_ns.a.dne import dne
 
 af("abc")
 bf(False)
@@ -132,16 +132,16 @@ af(False)
 bf(2)
 dne("abc")
 [out]
-testTypedPkgNamespaceImportFrom.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.ns.dne"
+testTypedPkgNamespaceImportFrom.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.a.dne"
 testTypedPkgNamespaceImportFrom.py:4: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 testTypedPkgNamespaceImportFrom.py:10: error: Argument 1 to "af" has incompatible type "bool"; expected "str"
 testTypedPkgNamespaceImportFrom.py:11: error: Argument 1 to "bf" has incompatible type "int"; expected "bool"
 
 [case testTypedPkgNamespaceImportAs]
-# pkgs: typedpkg, typedpkg_ns
+# pkgs: typedpkg, typedpkg_ns_a
 import typedpkg.pkg.aaa as nm; af = nm.af
-import typedpkg_ns.ns.bbb as am; bf = am.bf
-from typedpkg_ns.ns.dne import dne
+import typedpkg_ns.a.bbb as am; bf = am.bf
+from typedpkg_ns.a.dne import dne
 
 af("abc")
 bf(False)
@@ -151,16 +151,16 @@ af(False)
 bf(2)
 dne("abc")
 [out]
-testTypedPkgNamespaceImportAs.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.ns.dne"
+testTypedPkgNamespaceImportAs.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.a.dne"
 testTypedPkgNamespaceImportAs.py:4: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 testTypedPkgNamespaceImportAs.py:10: error: Argument 1 has incompatible type "bool"; expected "str"
 testTypedPkgNamespaceImportAs.py:11: error: Argument 1 has incompatible type "int"; expected "bool"
 
 [case testTypedPkgNamespaceRegImport]
-# pkgs: typedpkg, typedpkg_ns
+# pkgs: typedpkg, typedpkg_ns_a
 import typedpkg.pkg.aaa; af = typedpkg.pkg.aaa.af
-import typedpkg_ns.ns.bbb; bf = typedpkg_ns.ns.bbb.bf
-from typedpkg_ns.ns.dne import dne
+import typedpkg_ns.a.bbb; bf = typedpkg_ns.a.bbb.bf
+from typedpkg_ns.a.dne import dne
 
 af("abc")
 bf(False)
@@ -171,7 +171,7 @@ bf(2)
 dne("abc")
 
 [out]
-testTypedPkgNamespaceRegImport.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.ns.dne"
+testTypedPkgNamespaceRegImport.py:4: error: Cannot find implementation or library stub for module named "typedpkg_ns.a.dne"
 testTypedPkgNamespaceRegImport.py:4: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
 testTypedPkgNamespaceRegImport.py:10: error: Argument 1 has incompatible type "bool"; expected "str"
 testTypedPkgNamespaceRegImport.py:11: error: Argument 1 has incompatible type "int"; expected "bool"
@@ -188,9 +188,37 @@ import a
 a.py:1: error: Unsupported operand types for + ("int" and "str")
 
 [case testTypedPkgNamespaceRegFromImportTwice]
-# pkgs: typedpkg_ns
-from typedpkg_ns import ns
+# pkgs: typedpkg_ns_a
+from typedpkg_ns import a
 -- dummy should trigger a second iteration
 [file dummy.py.2]
 [out]
 [out2]
+
+[case testNamespacePkgWStubs]
+# pkgs: typedpkg_ns_a, typedpkg_ns_b, typedpkg_ns_b-stubs
+# flags: --no-namespace-packages
+import typedpkg_ns.a.bbb as a
+import typedpkg_ns.b.bbb as b
+a.bf(False)
+b.bf(False)
+a.bf(1)
+b.bf(1)
+[out]
+testNamespacePkgWStubs.py:4: error: Skipping analyzing "typedpkg_ns.b.bbb": found module but no type hints or library stubs
+testNamespacePkgWStubs.py:4: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
+testNamespacePkgWStubs.py:4: error: Skipping analyzing "typedpkg_ns.b": found module but no type hints or library stubs
+testNamespacePkgWStubs.py:7: error: Argument 1 to "bf" has incompatible type "int"; expected "bool"
+
+[case testNamespacePkgWStubsWithNamespacePackagesFlag]
+# pkgs: typedpkg_ns_a, typedpkg_ns_b, typedpkg_ns_b-stubs
+# flags: --namespace-packages
+import typedpkg_ns.a.bbb as a
+import typedpkg_ns.b.bbb as b
+a.bf(False)
+b.bf(False)
+a.bf(1)
+b.bf(1)
+[out]
+testNamespacePkgWStubsWithNamespacePackagesFlag.py:7: error: Argument 1 to "bf" has incompatible type "int"; expected "bool"
+testNamespacePkgWStubsWithNamespacePackagesFlag.py:8: error: Argument 1 to "bf" has incompatible type "int"; expected "bool"