Add more test

- multiple inheritance bases
- multiple inheritance levels
- overriding
- binding one type variable to another

Author: kitsuyui

test-data/unit/check-generics.test

@@ -1829,3 +1829,83 @@ reveal_type(C.f)  # E: Revealed type is 'def () -> builtins.int*'
 reveal_type(C.f())  # E: Revealed type is 'builtins.int*'
 [builtins fixtures/classmethod.pyi]
 [out]
+
+[case testClassMethodOfGenericClassMultipleInheritance]
+from typing import TypeVar, Generic
+t = TypeVar('t')
+class A(Generic[t]):
+    @classmethod
+    def f(cls) -> t: ...
+class B(A[str]): pass
+class C(A[int]): pass
+reveal_type(B.f)  # E: Revealed type is 'def () -> builtins.str*'
+reveal_type(B.f())  # E: Revealed type is 'builtins.str*'
+reveal_type(C.f)  # E: Revealed type is 'def () -> builtins.int*'
+reveal_type(C.f())  # E: Revealed type is 'builtins.int*'
+[builtins fixtures/classmethod.pyi]
+[out]
+
+[case testClassMethodOfGenericClassMultipleLevelInheritance]
+from typing import TypeVar, Generic
+t = TypeVar('t')
+class A(Generic[t]):
+    @classmethod
+    def f(cls) -> t: ...
+class B(A[str]): pass
+class C(B): pass
+class D(C): pass
+class E(D): pass
+reveal_type(C.f)  # E: Revealed type is 'def () -> builtins.str*'
+reveal_type(C.f())  # E: Revealed type is 'builtins.str*'
+reveal_type(D.f)  # E: Revealed type is 'def () -> builtins.str*'
+reveal_type(D.f())  # E: Revealed type is 'builtins.str*'
+reveal_type(E.f)  # E: Revealed type is 'def () -> builtins.str*'
+reveal_type(E.f())  # E: Revealed type is 'builtins.str*'
+[builtins fixtures/classmethod.pyi]
+[out]
+
+[case testClassMethodOfMultipleGenericClass]
+from typing import TypeVar, Generic
+t = TypeVar('t')
+class A(Generic[t]):
+    @classmethod
+    def f(cls) -> t: ...
+class B(Generic[t]):
+    @classmethod
+    def f(cls) -> t: ...
+class C(A[str], B[int]): pass
+class D(A[int], B[str]): pass
+reveal_type(C.f)  # E: Revealed type is 'def () -> builtins.str'
+reveal_type(C.f())  # E: Revealed type is 'builtins.str'
+reveal_type(D.f)  # E: Revealed type is 'def () -> builtins.int'
+reveal_type(D.f())  # E: Revealed type is 'builtins.int'
+[builtins fixtures/classmethod.pyi]
+[out]
+
+[case testClassMethodOfGenericClassOverriding]
+from typing import Generic, TypeVar
+t = TypeVar('t')
+class A(Generic[t]):
+    @classmethod
+    def f(cls) -> t: pass
+class B(A[str]):
+    @classmethod
+    def f(cls) -> str: pass
+class C(A[str]):
+    @classmethod
+    def f(cls) -> int: pass  # E: Return type of "f" incompatible with supertype "A"
+[builtins fixtures/classmethod.pyi]
+[out]
+
+[case testClassMethodOfGenericClassWithBindingAnotherTypeVariable]
+from typing import Generic, TypeVar
+t = TypeVar('t')
+s = TypeVar('s')
+class A(Generic[t]):
+    @classmethod
+    def f(cls) -> t: pass
+class B(A[s]): pass
+reveal_type(A.f())  # E: Revealed type is '<nothing>'
+reveal_type(B.f())  # E: Revealed type is '<nothing>'
+[builtins fixtures/classmethod.pyi]
+[out]