fix: leak checker needs callback support for legacy tests

Author: nbbeeken

.mocharc.json

@@ -3,7 +3,7 @@
   "require": [
     "source-map-support/register",
     "ts-node/register",
-    "test/tools/runner/chai-addons.js",
+    "test/tools/runner/chai_addons.ts",
     "test/tools/runner/hooks/unhandled_checker.ts"
   ],
   "extension": [

test/mocha_mongodb.json

@@ -3,7 +3,7 @@
   "require": [
     "source-map-support/register",
     "ts-node/register",
-    "test/tools/runner/chai-addons.js",
+    "test/tools/runner/chai_addons.ts",
     "test/tools/runner/hooks/configuration.ts",
     "test/tools/runner/hooks/unhandled_checker.ts",
     "test/tools/runner/hooks/leak_checker.ts",

test/tools/runner/chai-addons.js renamed to test/tools/runner/chai_addons.ts

@@ -1,7 +1,7 @@
-'use strict';
+/* eslint-disable @typescript-eslint/no-var-requires */
+
+import chai = require('chai');
 
-// configure chai
-const chai = require('chai');
 chai.use(require('sinon-chai'));
 chai.use(require('chai-subset'));
 chai.use(require('../spec-runner/matcher').default);

test/tools/runner/hooks/leak_checker.ts

@@ -55,12 +55,26 @@ class LeakChecker {
 
   setupClientLeakChecker() {
     const leakChecker = this;
-    MongoClient.prototype.connect = async function () {
+    MongoClient.prototype.connect = function (...args) {
       leakChecker.clients.add(this);
       this[LeakChecker.kConnectCount] ??= 0;
-      await LeakChecker.originalConnect.call(this);
-      this[LeakChecker.kConnectCount] += 1; // only increment on successful connects
-      return this;
+
+      const lastArg = args[args.length - 1];
+      const lastArgIsCallback = typeof lastArg === 'function';
+      if (lastArgIsCallback) {
+        const argsWithoutCallback = args.slice(0, args.length - 1);
+        return LeakChecker.originalConnect.call(this, ...argsWithoutCallback, (error, client) => {
+          if (error == null) {
+            this[LeakChecker.kConnectCount] += 1; // only increment on successful connects
+          }
+          return lastArg(error, client);
+        });
+      } else {
+        return LeakChecker.originalConnect.call(this, ...args).then(client => {
+          this[LeakChecker.kConnectCount] += 1; // only increment on successful connects
+          return client;
+        });
+      }
     };
 
     MongoClient.prototype.close = function (...args) {