test cases for the new handling of iterators by the is operator

tests/types/tisopr.nim

@@ -1,5 +1,8 @@
 discard """
-  output: "true true false yes"
+  output: '''true
+true
+false
+yes'''
 """
 
 proc IsVoid[T](): string = 
@@ -11,3 +14,26 @@ proc IsVoid[T](): string =
 const x = int is int
 echo x, " ", float is float, " ", float is string, " ", IsVoid[void]()
 
+template yes(e: expr): stmt =
+  static: assert e
+
+template no(e: expr): stmt =
+  static: assert(not e)
+
+var s = @[1, 2, 3]
+
+yes s.items is iterator
+no  s.items is proc
+
+yes s.items is iterator: int
+no  s.items is iterator: float
+
+yes s.items is iterator: TNumber
+no  s.items is iterator: object
+
+type 
+  Iter[T] = iterator: T
+
+yes s.items is Iter[TNumber]
+no  s.items is Iter[float]
+