Add opcode support for itxnas and gitxnas

pyteal/ast/gitxn.py

@@ -59,6 +59,15 @@ def __str__(self):
     def __teal__(self, options: "CompileOptions"):
         verifyFieldVersion(self.field.arg_name, self.field.min_version, options.version)
 
+        if type(self.txnIndex) is not int or not (
+            type(self.index) is int or isinstance(self.index, Expr)
+        ):
+            raise TealInputError(
+                "Invalid gitxna syntax with immediate transaction index {}, transaction field {}, array index {}".format(
+                    self.txnIndex, self.field, self.index
+                )
+            )
+
         if type(self.index) is int:
             opToUse = Op.gitxna
         else:
@@ -98,7 +107,7 @@ def __getitem__(self, txnIndex: int) -> TxnObject:
 
         return TxnObject(
             lambda field: GitxnExpr(txnIndex, field),
-            lambda field, index: GitxnaExpr(txnIndex, field, cast(int, index)),
+            lambda field, index: GitxnaExpr(txnIndex, field, index),
         )
 
 

pyteal/ast/gitxn_test.py

@@ -21,10 +21,21 @@ def test_gitxn_invalid():
 
 
 def test_gitxn_valid():
-    GitxnaExpr(0, TxnField.application_args, 1).__teal__(teal6Options)
-
     for i in range(MAX_GROUP_SIZE):
         Gitxn[i].sender()
 
 
+def test_gitxna_invalid():
+    with pytest.raises(TealInputError):
+        GitxnaExpr("Invalid_type", TxnField.application_args, 1).__teal__(teal6Options)
+
+    with pytest.raises(TealInputError):
+        GitxnaExpr(0, TxnField.application_args, "Invalid_type").__teal__(teal6Options)
+
+
+def test_gitxna_valid():
+    GitxnaExpr(0, TxnField.application_args, 1).__teal__(teal6Options)
+    GitxnaExpr(0, TxnField.application_args, Assert(Int(1))).__teal__(teal6Options)
+
+
 # txn_test.py performs additional testing