[mongoose] Added connection options related to auto encryption using CSFLE (#43723)

* added new connection options related to the new feature csfle

* added basic test case for auto-encryption in mongoose client connection

types/mongoose/index.d.ts

@@ -37,6 +37,7 @@
 //                 Dongjun Lee <https://github.com/ChazEpps>
 //                 Valentin Agachi <https://github.com/avaly>
 //		           Jan Nemcik <https://github.com/JanNemcik>
+//                 Cl3dson <https://github.com/cl3dson> 
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
 // TypeScript Version: 3.0
 
@@ -395,6 +396,15 @@ declare module "mongoose" {
      * is set to true.(default: false) */
     autoCreate?: boolean;
 
+
+    /** Configure csfle as especified in MongoDB official guide */
+    autoEncryption?: {
+      keyVaultNamespace: string,
+      kmsProviders: any,
+      schemaMap: any,
+      extraOptions?: any
+    }
+
     /** Specify a journal write concern (default: false). */
     journal?: boolean;
 

types/mongoose/mongoose-tests.ts

@@ -37,6 +37,22 @@ const connection3 = mongoose.connect(connectUri, function (error) {
   error.stack;
 });
 
+/**
+ * Test taken from MongoDB CSFLE guide 
+ * https://docs.mongodb.com/drivers/use-cases/client-side-field-level-encryption-guide
+ */
+
+const connection4:Promise<mongoose.Mongoose> = mongoose.connect(connectUri,{
+  useNewUrlParser: true,
+  useUnifiedTopology: true,
+  autoEncryption: {
+    keyVaultNamespace: 'encryption.__keyVault',
+    kmsProviders: {},
+    schemaMap: {},
+    extraOptions: {}
+  }
+})
+
 var mongooseConnection: mongoose.Connection = mongoose.createConnection();
 mongooseConnection.dropDatabase().then(()=>{});
 mongooseConnection.dropCollection('foo').then(()=>{});