fix(NODE-5296): construct error messages for AggregateErrors in Node16+

global.d.ts

@@ -12,6 +12,7 @@ declare global {
       serverless?: 'forbid' | 'allow' | 'require';
       auth?: 'enabled' | 'disabled';
       idmsMockServer?: true;
+      nodejs?: string;
     };
 
     sessions?: {

src/error.ts

@@ -108,6 +108,16 @@ export interface ErrorDescription extends Document {
   errInfo?: Document;
 }
 
+function isAggregateError(e: unknown): e is Error & { errors: Error[] } {
+  return (
+    typeof e === 'object' &&
+    e != null &&
+    e instanceof Error &&
+    'errors' in e &&
+    Array.isArray(e.errors)
+  );
+}
+
 /**
  * @public
  * @category Error
@@ -132,7 +142,13 @@ export class MongoError extends Error {
 
   constructor(message: string | Error) {
     if (message instanceof Error) {
-      super(message.message);
+      if (isAggregateError(message)) {
+        const combinedMessage = 'Aggregate Error: ' + message.errors.map(e => e.message).join(', ');
+        super(combinedMessage);
+      } else {
+        super(message.message);
+      }
+
       this.cause = message;
     } else {
       super(message);

test/integration/node-specific/errors.ts

@@ -0,0 +1,40 @@
+import { expect } from 'chai';
+
+import { MongoClient, MongoError } from '../../mongodb';
+
+describe('Error (Integration)', function () {
+  describe('AggregateErrors', function () {
+    it('constructs the message properly', { requires: { nodejs: '>=16' } }, () => {
+      for (const { errors, message } of [
+        { errors: [], message: 'Aggregate Error: ' },
+        { errors: [new Error('message 1')], message: 'Aggregate Error: message 1' },
+        {
+          errors: [new Error('message 1'), new Error('message 2')],
+          message: 'Aggregate Error: message 1, message 2'
+        }
+      ]) {
+        const error = new AggregateError(errors);
+        const mongoError = new MongoError(error);
+
+        expect(
+          mongoError.message,
+          `built the message properly with an array of ${errors.length} errors`
+        ).to.equal(message);
+      }
+    });
+
+    it('sets the aggregate error to the cause property', { requires: { nodejs: '>=16' } }, () => {
+      const error = new AggregateError([new Error('error 1')]);
+      const mongoError = new MongoError(error);
+      expect(mongoError.cause).to.equal(error);
+    });
+  });
+
+  it('NODE-5296: handles aggregate errors from dns lookup', async function () {
+    const error = await MongoClient.connect('mongodb://localhost:27222', {
+      serverSelectionTimeoutMS: 1000
+    }).catch(e => e);
+    expect(error).to.be.instanceOf(Error);
+    expect(error.message).to.match(/ECONNREFUSED/);
+  });
+});

test/tools/runner/filters/node_version_filter.js

@@ -0,0 +1,26 @@
+'use strict';
+
+const { satisfies } = require('semver');
+
+/**
+ * Filter for specific nodejs versions
+ *
+ * example:
+ * metadata: {
+ *    requires: {
+ *      nodejs: '>=14'
+ *    }
+ * }
+ */
+class NodeVersionFilter {
+  filter(test) {
+    const nodeVersionRange = test?.metadata?.requires?.nodejs;
+    if (!nodeVersionRange) {
+      return true;
+    }
+
+    return satisfies(process.version, nodeVersionRange);
+  }
+}
+
+module.exports = NodeVersionFilter;