From a75c46b64613e898b3090ac2677ea4e0840842b1 Mon Sep 17 00:00:00 2001
From: Michael Tinker <michael.tinker@swirldslabs.com>
Date: Thu, 7 Dec 2023 16:40:08 -0600
Subject: [PATCH] Make transferTo() a no-op on same from/to accounts

Signed-off-by: Michael Tinker <michael.tinker@swirldslabs.com>
---
 .../token/impl/api/TokenServiceApiImpl.java        | 13 ++++++++-----
 .../impl/test/api/TokenServiceApiImplTest.java     | 14 ++++++++++++++
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/hedera-node/hedera-token-service-impl/src/main/java/com/hedera/node/app/service/token/impl/api/TokenServiceApiImpl.java b/hedera-node/hedera-token-service-impl/src/main/java/com/hedera/node/app/service/token/impl/api/TokenServiceApiImpl.java
index 9a6685fef1b0..cfd5af2d234e 100644
--- a/hedera-node/hedera-token-service-impl/src/main/java/com/hedera/node/app/service/token/impl/api/TokenServiceApiImpl.java
+++ b/hedera-node/hedera-token-service-impl/src/main/java/com/hedera/node/app/service/token/impl/api/TokenServiceApiImpl.java
@@ -274,11 +274,14 @@ public void transferFromTo(@NonNull AccountID fromId, @NonNull AccountID toId, l
             throw new IllegalArgumentException(
                     "Overflow on transfer of " + amount + " tinybars from " + fromId + " to " + toId);
         }
-        accountStore.put(from.copyBuilder()
-                .tinybarBalance(from.tinybarBalance() - amount)
-                .build());
-        accountStore.put(
-                to.copyBuilder().tinybarBalance(to.tinybarBalance() + amount).build());
+        if (!from.accountIdOrThrow().equals(to.accountIdOrThrow())) {
+            accountStore.put(from.copyBuilder()
+                    .tinybarBalance(from.tinybarBalance() - amount)
+                    .build());
+            accountStore.put(to.copyBuilder()
+                    .tinybarBalance(to.tinybarBalance() + amount)
+                    .build());
+        }
     }
 
     @Override
diff --git a/hedera-node/hedera-token-service-impl/src/test/java/com/hedera/node/app/service/token/impl/test/api/TokenServiceApiImplTest.java b/hedera-node/hedera-token-service-impl/src/test/java/com/hedera/node/app/service/token/impl/test/api/TokenServiceApiImplTest.java
index 32578353f97f..19f025a06ef0 100644
--- a/hedera-node/hedera-token-service-impl/src/test/java/com/hedera/node/app/service/token/impl/test/api/TokenServiceApiImplTest.java
+++ b/hedera-node/hedera-token-service-impl/src/test/java/com/hedera/node/app/service/token/impl/test/api/TokenServiceApiImplTest.java
@@ -322,6 +322,20 @@ void transfersRequestedValue() {
         assertEquals(23L, postTransferReceiver.tinybarBalance());
     }
 
+    @Test
+    void identicalFromToIsNoop() {
+        accountStore.put(Account.newBuilder()
+                .accountId(CONTRACT_ACCOUNT_ID)
+                .tinybarBalance(123L)
+                .smartContract(true)
+                .build());
+
+        subject.transferFromTo(CONTRACT_ACCOUNT_ID, CONTRACT_ACCOUNT_ID, 23L);
+
+        final var postTransfer = requireNonNull(accountState.get(CONTRACT_ACCOUNT_ID));
+        assertEquals(123L, postTransfer.tinybarBalance());
+    }
+
     @Test
     void refusesToTransferNegativeAmount() {
         assertThrows(