test that type errors inside the default are caught

Author: JelleZijlstra

test-data/unit/check-class-namedtuple.test

@@ -411,7 +411,7 @@ reveal_type(HasNone(1))  # E: Revealed type is 'Tuple[builtins.int, builtins.int
 
 class Parameterized(NamedTuple):
     x: int
-    y: List[int] = []
+    y: List[int] = [1] + [2]
 
 reveal_type(Parameterized(1))  # E: Revealed type is 'Tuple[builtins.int, builtins.list[builtins.int], fallback=__main__.Parameterized]'
 Parameterized(1, ['not an int'])  # E: List item 0 has incompatible type "str"
@@ -435,6 +435,13 @@ class X(NamedTuple):
     x: int
     y: int = 'not an int'  # E: Incompatible types in assignment (expression has type "str", variable has type "int")
 
+[case testNewNamedTupleErrorInDefault]
+# flags: --fast-parser --python-version 3.6
+from typing import NamedTuple
+
+class X(NamedTuple):
+    x: int = 1 + '1'  # E: Unsupported operand types for + ("int" and "str")
+
 [case testNewNamedTupleInheritance]
 # flags: --fast-parser --python-version 3.6
 from typing import cast, NamedTuple