Merge branch 'NODE-6090' into NODE-6120

Author: W-A-James

src/sessions.ts

@@ -369,6 +369,11 @@ export class ClientSession extends TypedEventEmitter<ClientSessionEvents> {
   /**
    * Starts a new transaction with the given options.
    *
+   * @remarks
+   * **IMPORTANT**: Running operations in parallel is not supported during a transaction. The use of `Promise.all`,
+   * `Promise.allSettled`, `Promise.race`, etc to parallelize operations inside a transaction is
+   * undefined behaviour.
+   *
    * @param options - Options for the transaction
    */
   startTransaction(options?: TransactionOptions): void {
@@ -443,6 +448,11 @@ export class ClientSession extends TypedEventEmitter<ClientSessionEvents> {
    *
    * **IMPORTANT:** This method requires the function passed in to return a Promise. That promise must be made by `await`-ing all operations in such a way that rejections are propagated to the returned promise.
    *
+   * **IMPORTANT:** Running operations in parallel is not supported during a transaction. The use of `Promise.all`,
+   * `Promise.allSettled`, `Promise.race`, etc to parallelize operations inside a transaction is
+   * undefined behaviour.
+   *
+   *
    * @remarks
    * - If all operations successfully complete and the `commitTransaction` operation is successful, then the provided function will return the result of the provided function.
    * - If the transaction is unable to complete or an error is thrown from within the provided function, then the provided function will throw an error.

test/integration/client-side-operations-timeout/node_csot.test.ts

@@ -7,6 +7,7 @@ import {
   type Collection,
   type Db,
   type FindCursor,
+  LEGACY_HELLO_COMMAND,
   type MongoClient,
   MongoOperationTimeoutError
 } from '../../mongodb';
@@ -109,38 +110,40 @@ describe('CSOT driver tests', () => {
 
       beforeEach(async function () {
         configClient = this.configuration.newClient();
-        await configClient
+        const result = await configClient
           .db()
           .admin()
           .command({
             configureFailPoint: 'failCommand',
             mode: 'alwaysOn',
             data: {
-              failCommands: ['ping'],
+              failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
               blockConnection: true,
               blockTimeMS: 10
             }
           });
+        expect(result).to.have.property('ok', 1);
       });
 
       afterEach(async function () {
-        await configClient
+        const result = await configClient
           .db()
           .admin()
           .command({
             configureFailPoint: 'failCommand',
             mode: 'off',
             data: {
-              failCommands: ['ping'],
+              failCommands: ['ping', 'hello', LEGACY_HELLO_COMMAND],
               blockConnection: true,
               blockTimeMS: 10
             }
           });
+        expect(result).to.have.property('ok', 1);
         await configClient.close();
       });
 
       it('throws a MongoOperationTimeoutError', {
-        metadata: { requires: { mongodb: '>=4.2' } },
+        metadata: { requires: { mongodb: '>=4.4' } },
         test: async function () {
           const commandsStarted = [];
           client = this.configuration.newClient(undefined, { timeoutMS: 1, monitorCommands: true });
@@ -156,10 +159,10 @@ describe('CSOT driver tests', () => {
               e => e
             );
 
-          expect(commandsStarted).to.have.length(0); // Ensure that we fail before we start the insertOne
-
           expect(maybeError).to.exist;
           expect(maybeError).to.be.instanceof(MongoOperationTimeoutError);
+
+          expect(commandsStarted).to.have.length(0); // Ensure that we fail before we start the insertOne
         }
       });
     });