feat: support driver info for drivers wrapping the node driver

This allows drivers that wrap the node driver (e.g. Mongoose) report
information about themselves in the client metadata generated by
the driver.

lib/core/topologies/shared.js

@@ -56,6 +56,21 @@ function createClientInfo(options) {
     clientInfo.application = { name: appname };
   }
 
+  // support optionally provided wrapping driver info
+  if (options.driverInfo) {
+    if (options.driverInfo.name) {
+      clientInfo.driver.name = `${clientInfo.driver.name}|${options.driverInfo.name}`;
+    }
+
+    if (options.driverInfo.version) {
+      clientInfo.driver.version = `${clientInfo.driver.version}|${options.driverInfo.version}`;
+    }
+
+    if (options.driverInfo.platform) {
+      clientInfo.platform = `${clientInfo.platform}|${options.driverInfo.platform}`;
+    }
+  }
+
   return clientInfo;
 }
 

lib/mongo_client.js

@@ -77,6 +77,15 @@ const CloseOperation = require('./operations/close');
  * @property {string[]} [extraOptions.mongocryptdSpawnArgs] Command line arguments to use when auto-spawning a mongocryptd
  */
 
+/**
+ * Configuration options for drivers wrapping the node driver.
+ *
+ * @typedef {Object} DriverInfoOptions
+ * @property {string} [name] The name of the driver
+ * @property {string} [version] The version of the driver
+ * @property {string} [platform] Optional platform information
+ */
+
 /**
  * Creates a new MongoClient instance
  * @class
@@ -143,6 +152,7 @@ const CloseOperation = require('./operations/close');
  * @param {boolean} [options.useNewUrlParser=true] Determines whether or not to use the new url parser. Enables the new, spec-compliant, url parser shipped in the core driver. This url parser fixes a number of problems with the original parser, and aims to outright replace that parser in the near future. Defaults to true, and must be explicitly set to false to use the legacy url parser.
  * @param {boolean} [options.useUnifiedTopology] Enables the new unified topology layer
  * @param {AutoEncryptionOptions} [options.autoEncryption] Optionally enable client side auto encryption
+ * @param {DriverInfoOptions} [options.driverInfo] Allows a wrapping driver to amend the client metadata generated by the driver to include information about the wrapping driver
  * @param {MongoClient~connectCallback} [callback] The command result callback
  * @return {MongoClient} a MongoClient instance
  */

lib/operations/connect.js

@@ -137,7 +137,8 @@ const validOptionNames = [
   'useUnifiedTopology',
   'serverSelectionTimeoutMS',
   'useRecoveryToken',
-  'autoEncryption'
+  'autoEncryption',
+  'driverInfo'
 ];
 
 const ignoreOptionNames = ['native_parser'];

test/unit/client_tests.js

@@ -0,0 +1,50 @@
+'use strict';
+
+const expect = require('chai').expect;
+const mock = require('mongodb-mock-server');
+
+describe('Client (unit)', function() {
+  let server;
+
+  afterEach(() => mock.cleanup());
+  beforeEach(() => {
+    return mock.createServer().then(_server => (server = _server));
+  });
+
+  it('should let wrapping libraries amend the client metadata', function() {
+    let handshake;
+    server.setMessageHandler(request => {
+      const doc = request.document;
+      if (doc.ismaster) {
+        handshake = doc;
+        request.reply(Object.assign({}, mock.DEFAULT_ISMASTER));
+      } else if (doc.endSessions) {
+        request.reply({ ok: 1 });
+      }
+    });
+
+    const client = this.configuration.newClient(`mongodb://${server.uri()}/`, {
+      useUnifiedTopology: true,
+      driverInfo: {
+        name: 'mongoose',
+        version: '5.7.10',
+        platform: 'llama edition'
+      }
+    });
+
+    return client.connect().then(() => {
+      this.defer(() => client.close());
+
+      expect(handshake)
+        .nested.property('client.driver')
+        .to.deep.equal({
+          name: 'nodejs|mongoose',
+          version: '3.3.4|5.7.10'
+        });
+
+      expect(handshake)
+        .nested.property('client.platform')
+        .to.match(/llama edition/);
+    });
+  });
+});