Add failing unit test for ininstance with type objects

Author: pkch

test-data/unit/check-isinstance.test

@@ -1354,3 +1354,21 @@ def f(x: Union[int, str], typ: type) -> None:
     else:
         reveal_type(x)  # E: Revealed type is 'Union[builtins.int, builtins.str]'
 [builtins fixtures/isinstancelist.pyi]
+
+
+[case testIsInstanceWithTypeObject]
+from typing import Union, Type
+
+class A: pass
+
+def f(x: Union[int, A], a: Type[A]) -> None:
+    if isinstance(x, a):
+        reveal_type(x)  # E: Revealed type is '__main__.A'
+    elif isinstance(x, int):
+        reveal_type(x)  # E: Revealed type is 'builtins.int'
+    else:
+        reveal_type(x)  # E: Revealed type is '__main__.A'
+    reveal_type(x)  # E: Revealed type is 'Union[builtins.int, __main__.A]'
+
+[builtins fixtures/isinstancelist.pyi]
+