Add union destructuring test

Author: pkch

test-data/unit/check-isinstance.test

@@ -1443,6 +1443,28 @@ else:
 [builtins fixtures/isinstancelist.pyi]
 
 
+[case testIssubclasDestructuringUnions]
+from typing import Union, List, Tuple, Dict, Type
+def f(x: Union[Type[int], Type[str], Type[List]]) -> None:
+    if issubclass(x, (str, (int,))):
+        reveal_type(x)  # E: Revealed type is 'Union[Type[builtins.int], Type[builtins.str]]'
+        reveal_type(x())  # E: Revealed type is 'Union[builtins.int, builtins.str]'
+        x()[1]  # E: Value of type "Union[int, str]" is not indexable
+    else:
+        reveal_type(x)  # E: Revealed type is 'Type[builtins.list]'
+        reveal_type(x())  # E: Revealed type is 'builtins.list[<uninhabited>]'
+        x()[1]
+    reveal_type(x)  # E: Revealed type is 'Union[Type[builtins.int], Type[builtins.str], Type[builtins.list]]'
+    reveal_type(x())  # E: Revealed type is 'Union[builtins.int, builtins.str, builtins.list[<uninhabited>]]'
+    if issubclass(x, (str, (list,))):
+        reveal_type(x)  # E: Revealed type is 'Union[Type[builtins.str], Type[builtins.list[Any]]]'
+        reveal_type(x())  # E: Revealed type is 'Union[builtins.str, builtins.list[<uninhabited>]]'
+        x()[1]
+    reveal_type(x)  # E: Revealed type is 'Union[Type[builtins.int], Type[builtins.str], Type[builtins.list[Any]]]'
+    reveal_type(x())  # E: Revealed type is 'Union[builtins.int, builtins.str, builtins.list[<uninhabited>]]'
+[builtins fixtures/isinstancelist.pyi]
+
+
 [case testIssubclass]
 from typing import Type, ClassVar