test/stubgen: fill more tests on stubs

tests/schemas/test_stubs.py

@@ -16,6 +16,9 @@ if str(_HERE) not in sys.path:
     sys.path.insert(0, str(_HERE))
 
 import capnp  # pyright: ignore[reportMissingTypeStubs, reportUnusedImport]  # activates import hook
+import test_generics_capnp
+import test_interface_capnp
+import test_nested_capnp
 import test_simple_capnp
 
 
@@ -56,7 +59,6 @@ class TestNestedStub:
     """test_nested.capnp — nested types + lists."""
 
     def test_nested_message(self) -> None:
-        import test_nested_capnp
         ab = test_nested_capnp.AddressBook.new_message()
         assert ab.people is not None
 
@@ -65,6 +67,39 @@ class TestGenericsStub:
     """test_generics.capnp — generic structs."""
 
     def test_holder_loads(self) -> None:
-        import test_generics_capnp
         c = test_generics_capnp.Container.new_message()
         assert c is not None
+
+
+class TestInterfaceStub:
+    """test_interface.capnp — interfaces + method params."""
+
+    def test_calcserver_loads(self) -> None:
+        cs = test_interface_capnp.CalcServer.new_message()
+        assert cs is not None
+
+
+class TestAddressBookStub:
+    """addressbook.capnp — classic example."""
+
+    def test_person_new_message(self) -> None:
+        import addressbook_capnp
+        p = addressbook_capnp.Person.new_message(
+            name="Alice", email="alice@example.com"
+        )
+        assert p.name == "Alice"
+
+    def test_addressbook_new_message(self) -> None:
+        import addressbook_capnp
+        ab = addressbook_capnp.AddressBook.new_message()
+        assert ab.people is not None
+
+
+# dummy.capnp runtime tests skipped — its annotation imports (c.capnp,
+# c++.capnp) cause pycapnp's C++ SchemaParser to SIGABRT.  The generated
+# .pyi passes static type-checking and `capnp compile -opy` succeeds.
+
+
+# Note: multi/consumer.capnp cross-file import test skipped —
+# pycapnp's SchemaParser crashes when resolving annotation imports
+# across schema files. The .pyi stubs are still generated and kept.