update IsSponsorTx

tm2/pkg/std/tx.go

@@ -60,22 +60,25 @@ func (tx Tx) ValidateBasic() error {
 	return nil
 }
 
-// IsSponsorTx checks if the transaction is a sponsor transaction.
-// A sponsor transaction is defined as having:
-// - At least one message in the transaction.
-// - The first message type is "no_op".
-// - More than one signer.
-// - The first signer is different from all other signers.
+// IsSponsorTx checks if the transaction is a valid sponsor transaction
 func (tx Tx) IsSponsorTx() bool {
-	if len(tx.Msgs) == 0 || tx.Msgs[0].Type() != "no_op" {
+	// At least one message in the transaction
+	if len(tx.Msgs) < 1 {
 		return false
 	}
 
+	// The first message type is "no_op"
+	if tx.Msgs[0].Type() != "no_op" {
+		return false
+	}
+
+	// More than one signer
 	signers := tx.GetSigners()
 	if len(signers) <= 1 {
 		return false
 	}
 
+	// The first signer is different from all other signers
 	for i := 1; i < len(signers); i++ {
 		if signers[0] == signers[i] {
 			return false

tm2/pkg/std/tx_test.go

@@ -213,6 +213,16 @@ func TestIsSponsorTx(t *testing.T) {
 			},
 			expected: true,
 		},
+		{
+			name: "only have no_op message",
+			msgs: []Msg{
+				mockMsg{
+					caller:  addr1,
+					msgType: "no_op",
+				},
+			},
+			expected: false,
+		},
 		{
 			name: "no_op message with same signers",
 			msgs: []Msg{