From 728ab9ef1be3d5ba406916a569a158eacb70b7cc Mon Sep 17 00:00:00 2001
From: Neal Beeken <neal.beeken@mongodb.com>
Date: Fri, 9 Aug 2024 14:31:43 -0400
Subject: [PATCH] chore: add looping for writeErrors

---
 src/cmap/connection.ts                        |  5 ++-
 src/cmap/wire_protocol/responses.ts           | 37 +++++++++++++------
 .../node_csot.test.ts                         | 14 ++++---
 3 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/src/cmap/connection.ts b/src/cmap/connection.ts
index 68608d45b0..d70c86be70 100644
--- a/src/cmap/connection.ts
+++ b/src/cmap/connection.ts
@@ -621,7 +621,10 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
           }
         } else {
           if (
-            document?.writeErrors?.[0]?.code === MONGODB_ERROR_CODES.MaxTimeMSExpired ||
+            (Array.isArray(document?.writeErrors) &&
+              document.writeErrors.some(
+                error => error?.code === MONGODB_ERROR_CODES.MaxTimeMSExpired
+              )) ||
             document?.writeConcernError?.code === MONGODB_ERROR_CODES.MaxTimeMSExpired
           ) {
             throw new MongoOperationTimeoutError('Server reported a timeout error', {
diff --git a/src/cmap/wire_protocol/responses.ts b/src/cmap/wire_protocol/responses.ts
index a7d520eb38..347e84f9c1 100644
--- a/src/cmap/wire_protocol/responses.ts
+++ b/src/cmap/wire_protocol/responses.ts
@@ -111,18 +111,31 @@ export class MongoDBResponse extends OnDemandDocument {
    * - ok is 1 and the writeConcern object contains a code === 50
    */
   get isMaxTimeExpiredError() {
-    return (
-      // {ok: 0, code: 50 ... }
-      (this.ok === 0 && this.code === MONGODB_ERROR_CODES.MaxTimeMSExpired) ||
-      // {ok: 1, writeErrors: [{code: 50 ... }]}
-      (this.ok === 1 &&
-        this.get('writeErrors', BSONType.array)?.get(0, BSONType.object)?.getNumber('code') ===
-          MONGODB_ERROR_CODES.MaxTimeMSExpired) ||
-      // {ok: 1, writeConcernError: {code: 50 ... }}
-      (this.ok === 1 &&
-        this.get('writeConcernError', BSONType.object)?.getNumber('code') ===
-          MONGODB_ERROR_CODES.MaxTimeMSExpired)
-    );
+    // {ok: 0, code: 50 ... }
+    const isTopLevel = this.ok === 0 && this.code === MONGODB_ERROR_CODES.MaxTimeMSExpired;
+    if (isTopLevel) return true;
+
+    if (this.ok === 0) return false;
+
+    // {ok: 1, writeConcernError: {code: 50 ... }}
+    const isWriteConcern =
+      this.get('writeConcernError', BSONType.object)?.getNumber('code') ===
+      MONGODB_ERROR_CODES.MaxTimeMSExpired;
+    if (isWriteConcern) return true;
+
+    const writeErrors = this.get('writeErrors', BSONType.array);
+    if (writeErrors?.size()) {
+      for (let i = 0; i < writeErrors.size(); i++) {
+        const isWriteError =
+          writeErrors.get(i, BSONType.object)?.getNumber('code') ===
+          MONGODB_ERROR_CODES.MaxTimeMSExpired;
+
+        // {ok: 1, writeErrors: [{code: 50 ... }]}
+        if (isWriteError) return true;
+      }
+    }
+
+    return false;
   }
 
   /**
diff --git a/test/integration/client-side-operations-timeout/node_csot.test.ts b/test/integration/client-side-operations-timeout/node_csot.test.ts
index 1fccd505de..53975bbc12 100644
--- a/test/integration/client-side-operations-timeout/node_csot.test.ts
+++ b/test/integration/client-side-operations-timeout/node_csot.test.ts
@@ -1,11 +1,11 @@
 /* Anything javascript specific relating to timeouts */
 import { expect } from 'chai';
-import * as semver from 'semver';
 import * as sinon from 'sinon';
 
 import {
   BSON,
   type ClientSession,
+  Code,
   type Collection,
   Connection,
   type Db,
@@ -232,14 +232,16 @@ describe('CSOT driver tests', () => {
       });
 
       describe('when a maxTimeExpired error is returned inside a writeErrors array', () => {
-        // Okay so allegedly this can never happen.
-        // But the spec says it can, so let's be defensive and support it.
-        // {ok: 1, writeErrors: [{code: 50, codeName: "MaxTimeMSExpired", errmsg: "operation time limit exceeded"}]}
+        // The server should always return one maxTimeExpiredError at the front of the writeErrors array
+        // But for the sake of defensive programming we will find any maxTime error in the array.
 
         beforeEach(async () => {
           const writeErrorsReply = BSON.serialize({
             ok: 1,
             writeErrors: [
+              { code: 2, codeName: 'MaxTimeMSExpired', errmsg: 'operation time limit exceeded' },
+              { code: 3, codeName: 'MaxTimeMSExpired', errmsg: 'operation time limit exceeded' },
+              { code: 4, codeName: 'MaxTimeMSExpired', errmsg: 'operation time limit exceeded' },
               { code: 50, codeName: 'MaxTimeMSExpired', errmsg: 'operation time limit exceeded' }
             ]
           });
@@ -268,10 +270,10 @@ describe('CSOT driver tests', () => {
             .catch(error => error);
           expect(error).to.be.instanceOf(MongoOperationTimeoutError);
           expect(error.cause).to.be.instanceOf(MongoServerError);
-          expect(error.cause).to.have.nested.property('writeErrors[0].code', 50);
+          expect(error.cause).to.have.nested.property('writeErrors[3].code', 50);
 
           expect(commandsSucceeded).to.have.lengthOf(1);
-          expect(commandsSucceeded).to.have.nested.property('[0].reply.writeErrors[0].code', 50);
+          expect(commandsSucceeded).to.have.nested.property('[0].reply.writeErrors[3].code', 50);
         });
       });