Merge pull request #14661 from Automattic/vkarpov15/gh-14656

types(connection): make transaction() return type match the executor function

Author: vkarpov15

test/docs/transactions.test.js

@@ -479,7 +479,7 @@ describe('transactions', function() {
     const doc = await Test.findById(_id).orFail();
     let attempt = 0;
 
-    await db.transaction(async(session) => {
+    const res = await db.transaction(async(session) => {
       await doc.save({ session });
 
       if (attempt === 0) {
@@ -489,7 +489,10 @@ describe('transactions', function() {
           errorLabels: [mongoose.mongo.MongoErrorLabel.TransientTransactionError]
         });
       }
+
+      return { answer: 42 };
     });
+    assert.deepStrictEqual(res, { answer: 42 });
 
     const { items } = await Test.findById(_id).orFail();
     assert.ok(Array.isArray(items));

test/types/connection.test.ts

@@ -45,11 +45,11 @@ expectType<mongodb.Db>(conn.db);
 expectType<mongodb.MongoClient>(conn.getClient());
 expectType<Connection>(conn.setClient(new mongodb.MongoClient('mongodb://127.0.0.1:27017/test')));
 
-expectType<Promise<void>>(conn.transaction(async(res) => {
+expectType<Promise<string>>(conn.transaction(async(res) => {
   expectType<mongodb.ClientSession>(res);
   return 'a';
 }));
-expectType<Promise<void>>(conn.transaction(async(res) => {
+expectType<Promise<string>>(conn.transaction(async(res) => {
   expectType<mongodb.ClientSession>(res);
   return 'a';
 }, { readConcern: 'majority' }));

types/connection.d.ts

@@ -236,7 +236,7 @@ declare module 'mongoose' {
      * async function executes successfully and attempt to retry if
      * there was a retryable error.
      */
-    transaction(fn: (session: mongodb.ClientSession) => Promise<any>, options?: mongodb.TransactionOptions): Promise<void>;
+    transaction<ReturnType = unknown>(fn: (session: mongodb.ClientSession) => Promise<ReturnType>, options?: mongodb.TransactionOptions): Promise<ReturnType>;
 
     /** Switches to a different database using the same connection pool. */
     useDb(name: string, options?: { useCache?: boolean, noListener?: boolean }): Connection;