refactor: improve error handling for Tuple.set (#655)

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Unreleased
 
 ## Added
+* Improved error handling for tuple type mismatch: added information on position and expected type. ([#655](https://github.com/algorand/pyteal/pull/655))
 
 ## Fixed
 

pyteal/ast/abi/tuple.py

@@ -341,17 +341,18 @@ def set(self, *values):
         if len(values) == 1 and isinstance(values[0], ComputedValue):
             return self._set_with_computed_type(values[0])
 
-        for value in values:
-            if not isinstance(value, BaseType):
-                raise TealInputError(f"Expected BaseType, got {value}")
-
         myTypes = self.type_spec().value_type_specs()
         if len(myTypes) != len(values):
             raise TealInputError(
                 f"Incorrect length for values. Expected {len(myTypes)}, got {len(values)}"
             )
-        if not all(myTypes[i] == values[i].type_spec() for i in range(len(myTypes))):
-            raise TealInputError("Input values do not match type")
+        for index, (value, myType) in enumerate(zip(values, myTypes)):
+            if not isinstance(value, BaseType):
+                raise TealInputError(f"Expected BaseType, got {value}")
+            if myType != value.type_spec():
+                raise TealInputError(
+                    f"Input values do not match type at {index=}: {value.type_spec()} != {myType}"
+                )
         return self._stored_value.store(_encode_tuple(values))
 
     def encode(self) -> Expr:

pyteal/ast/abi/tuple_test.py

@@ -662,7 +662,7 @@ def test_Tuple_set():
     with pytest.raises(pt.TealInputError):
         tupleValue.set(uint8, uint16, uint32, uint32)
 
-    with pytest.raises(pt.TealInputError):
+    with pytest.raises(pt.TealInputError, match="at index=1: uint32 != uint16"):
         tupleValue.set(uint8, uint32, uint16)
 
     with pytest.raises(pt.TealInputError):