clarify branching timeout behaviour

Author: W-A-James

Diff for: src/cmap/connection_pool.ts

@@ -28,7 +28,7 @@ import {
 import { CancellationToken, TypedEventEmitter } from '../mongo_types';
 import type { Server } from '../sdam/server';
 import { Timeout, TimeoutError } from '../timeout';
-import { type Callback, List, makeCounter, promiseWithResolvers } from '../utils';
+import { type Callback, csotMin, List, makeCounter, promiseWithResolvers } from '../utils';
 import { connect } from './connect';
 import { Connection, type ConnectionEvents, type ConnectionOptions } from './connection';
 import {
@@ -370,7 +370,9 @@ export class ConnectionPool extends TypedEventEmitter<ConnectionPoolEvents> {
     if (options?.timeout) {
       // CSOT enabled
       // Determine if we're using the timeout passed in or a new timeout
-      if (options.timeout.duration === 0 || serverSelectionTimeoutMS < options.timeout.duration) {
+      if (
+        csotMin(options.timeout.duration, serverSelectionTimeoutMS) === serverSelectionTimeoutMS
+      ) {
         timeout = Timeout.expires(serverSelectionTimeoutMS - options.timeout.timeElapsed);
       } else {
         timeout = options.timeout;

Diff for: src/sdam/topology.ts

@@ -38,7 +38,6 @@ import { Timeout, TimeoutError } from '../timeout';
 import type { Transaction } from '../transactions';
 import {
   type Callback,
-  csotMin,
   type EventEmitterWithState,
   HostAddress,
   List,
@@ -569,7 +568,7 @@ export class Topology extends TypedEventEmitter<TopologyEvents> {
     if (options.timeout) {
       // CSOT Enabled
       timeout =
-        csotMin(options.timeout.remainingTime, serverSelectionTimeoutMS) ===
+        Math.min(options.timeout.remainingTime, serverSelectionTimeoutMS) ===
         serverSelectionTimeoutMS
           ? Timeout.expires(serverSelectionTimeoutMS)
           : options.timeout;