Add dedicated tests for key resolved issues

Author: ilevkivskyi

test-data/unit/check-generics.test

@@ -3563,3 +3563,18 @@ def foo(x: T):
     reveal_type(C)  # N: Revealed type is "Overload(def [T, S] (x: builtins.int, y: S`-1) -> __main__.C[__main__.Int[S`-1]], def [T, S] (x: builtins.str, y: S`-1) -> __main__.C[__main__.Str[S`-1]])"
     reveal_type(C(0, x))  # N: Revealed type is "__main__.C[__main__.Int[T`-1]]"
     reveal_type(C("yes", x))  # N: Revealed type is "__main__.C[__main__.Str[T`-1]]"
+
+[case testInstanceMethodBoundOnClass]
+from typing import TypeVar, Generic
+
+T = TypeVar("T")
+class B(Generic[T]):
+    def foo(self) -> T: ...
+class C(B[T]): ...
+class D(C[int]): ...
+
+reveal_type(B.foo)  # N: Revealed type is "def [T] (self: __main__.B[T`1]) -> T`1"
+reveal_type(B[int].foo)  # N: Revealed type is "def (self: __main__.B[builtins.int]) -> builtins.int"
+reveal_type(C.foo)  # N: Revealed type is "def [T] (self: __main__.B[T`1]) -> T`1"
+reveal_type(C[int].foo)  # N: Revealed type is "def (self: __main__.B[builtins.int]) -> builtins.int"
+reveal_type(D.foo)  # N: Revealed type is "def (self: __main__.B[builtins.int]) -> builtins.int"

test-data/unit/check-protocols.test

@@ -4460,3 +4460,48 @@ f2(a4)  # E: Argument 1 to "f2" has incompatible type "A4"; expected "P2" \
         # N:     foo: expected "B1", got "str" \
         # N:     foo: expected setter type "C1", got "str"
 [builtins fixtures/property.pyi]
+
+[case testProtocolImplementationWithDescriptors]
+from typing import Any, Protocol
+
+class Descr:
+    def __get__(self, inst: Any, owner: Any) -> int: ...
+
+class DescrBad:
+    def __get__(self, inst: Any, owner: Any) -> str: ...
+
+class Proto(Protocol):
+    x: int
+
+class C:
+    x = Descr()
+
+class CBad:
+    x = DescrBad()
+
+a: Proto = C()
+b: Proto = CBad()  # E: Incompatible types in assignment (expression has type "CBad", variable has type "Proto") \
+                   # N: Following member(s) of "CBad" have conflicts: \
+                   # N:     x: expected "int", got "str"
+
+[case testProtocolCheckDefersNode]
+from typing import Any, Callable, Protocol
+
+class Proto(Protocol):
+    def f(self) -> int:
+        ...
+
+def defer(f: Callable[[Any], int]) -> Callable[[Any], str]:
+    ...
+
+def bad() -> Proto:
+    return Impl()  # E: Incompatible return value type (got "Impl", expected "Proto") \
+                   # N: Following member(s) of "Impl" have conflicts: \
+                   # N:     Expected: \
+                   # N:         def f(self) -> int \
+                   # N:     Got: \
+                   # N:         def f() -> str \
+
+class Impl:
+    @defer
+    def f(self) -> int: ...