diff --git a/back/test/mail/saveMessage-test.ts b/back/test/mail/saveMessage-test.ts
index b2e5c5c..88328e5 100644
--- a/back/test/mail/saveMessage-test.ts
+++ b/back/test/mail/saveMessage-test.ts
@@ -54,6 +54,7 @@ import {
     incrementNotSeenRoom,
 } from "../../db/saveMessage-db";
 import { AttrsWithEnvelope } from "../../interfaces/mail/attrs.interface";
+import { AttrsWithEnvelopeTest, createReplyWithSameMembers } from "../test-utils/test-messageUtils";
 // todo esbuild
 // new message from us
 //     to multiple people -> room
@@ -88,10 +89,9 @@ beforeAll(async () => {
     mocked(incrementNotSeenRoom).mockImplementation(db.incrementNotSeenRoom);
 });
 
-let msgFromUs_1: { attrs: AttrsWithEnvelope; message_id: number };
-let replyTo1_2: { attrs: AttrsWithEnvelope; message_id: number };
-
-let replyTo2_3: { attrs: AttrsWithEnvelope; message_id: number };
+let msgFromUs_1: AttrsWithEnvelopeTest;
+let replyTo1_2: AttrsWithEnvelopeTest;
+let replyTo2_3: AttrsWithEnvelopeTest;
 
 beforeEach(async () => {
     msgFromUs_1 = {
@@ -221,13 +221,8 @@ describe("saveMessage", () => {
             await register.save();
             register = new registerMessageInApp(replyTo1_2.message_id, replyTo1_2.attrs, boxId);
             await register.save();
-            // set same members to not create a new thread
-            let newReplyInThread = JSON.parse(JSON.stringify(replyTo1_2));
-            newReplyInThread.attrs.envelope.inReplyTo = replyTo1_2.attrs.envelope.messageId;
-            newReplyInThread.message_id = randomInt(5);
-            newReplyInThread.attrs.envelope.messageId = newReplyInThread.message_id.toString();
-            db.messages.push(newReplyInThread);
 
+            let newReplyInThread = createReplyWithSameMembers(replyTo1_2, db);
             register = new registerMessageInApp(newReplyInThread.message_id, newReplyInThread.attrs, boxId);
             await register.save();
 
@@ -270,13 +265,7 @@ describe("saveMessage", () => {
             register = new registerMessageInApp(replyTo1_2.message_id, replyTo1_2.attrs, boxId);
             await register.save();
 
-            // set same members to not create a new thread
-            let newReplyInThread = JSON.parse(JSON.stringify(replyTo1_2));
-            newReplyInThread.attrs.envelope.inReplyTo = replyTo1_2.attrs.envelope.messageId;
-            newReplyInThread.message_id = randomInt(5);
-            newReplyInThread.attrs.envelope.messageId = newReplyInThread.message_id.toString();
-            db.messages.push(newReplyInThread);
-
+            let newReplyInThread = createReplyWithSameMembers(replyTo1_2, db);
             register = new registerMessageInApp(newReplyInThread.message_id, newReplyInThread.attrs, boxId);
             await register.save();
 
diff --git a/back/test/test-utils/test-messageUtils.ts b/back/test/test-utils/test-messageUtils.ts
new file mode 100644
index 0000000..32ca3d6
--- /dev/null
+++ b/back/test/test-utils/test-messageUtils.ts
@@ -0,0 +1,17 @@
+import { randomInt } from "crypto";
+import { AttrsWithEnvelope } from "../../interfaces/mail/attrs.interface";
+import saveMessageDatabase from "./db/test-saveMessage";
+
+export interface AttrsWithEnvelopeTest {
+    attrs: AttrsWithEnvelope;
+    message_id: number;
+}
+
+export function createReplyWithSameMembers(origin: AttrsWithEnvelopeTest, db?: saveMessageDatabase): AttrsWithEnvelopeTest {
+    const reply = JSON.parse(JSON.stringify(origin));
+    reply.attrs.envelope.inReplyTo = origin.attrs.envelope.messageId;
+    reply.message_id = randomInt(5);
+    reply.attrs.envelope.messageId = reply.message_id.toString();
+    db.messages.push(reply);
+    return reply;
+}
\ No newline at end of file