add snapshot test for topic delete tx

.snapshots/TestSerializeConsensusTopicDeleteTransaction

@@ -0,0 +1,28 @@
+bodyBytes: "\n\014\n\006\010\316\247\212\345\005\022\002\030\002\022\002\030\003\030\300\204=\"\004\010\200\243\005\322\001\004\n\002\030c"
+sigMap: <
+  sigPair: <
+    pubKeyPrefix: "\344\361\300\353L}\315\303\347\353\021p\263\010\212=\022\242\227\364\243\353\342\362\205\003\375g5F\355\216"
+    ed25519: "\340\240!e\360j(\230Y\352q\213\334,\335`\236v\247\326T\026c-\373&\024\004~\036P\304\024u\211\220\370\306R\267\024<\372\3220\272\205?\335J^:=\232\021NU2\207\315r\024\317\013"
+  >
+>
+transactionID: <
+  transactionValidStart: <
+    seconds: 1554158542
+  >
+  accountID: <
+    accountNum: 2
+  >
+>
+nodeAccountID: <
+  accountNum: 3
+>
+transactionFee: 1000000
+transactionValidDuration: <
+  seconds: 86400
+>
+consensusDeleteTopic: <
+  topicID: <
+    topicNum: 99
+  >
+>
+

consensus_topic_delete_transaction_test.go

@@ -0,0 +1,35 @@
+package hedera
+
+import (
+	"testing"
+	"time"
+
+	"github.com/bradleyjkemp/cupaloy"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSerializeConsensusTopicDeleteTransaction(t *testing.T) {
+	date := time.Unix(1554158542, 0)
+
+	testTopicID := ConsensusTopicID{Topic: 99}
+
+	key, err := Ed25519PrivateKeyFromString("302e020100300506032b6570042204203b054fade7a2b0869c6bd4a63b7017cbae7855d12acc357bea718e2c3e805962")
+	assert.NoError(t, err)
+
+	tx, err := NewConsensusTopicDeleteTransaction().
+		SetTopicID(testTopicID).
+		SetTransactionValidDuration(24 * time.Hour).
+		SetNodeAccountID(AccountID{Account: 3}).
+		SetTransactionID(TransactionID{
+			AccountID:  AccountID{Account: 2},
+			ValidStart: date,
+		}).
+		SetMaxTransactionFee(HbarFromTinybar(1e6)).
+		Build(nil)
+
+	assert.NoError(t, err)
+
+	tx.Sign(key)
+
+	cupaloy.SnapshotT(t, tx.String())
+}