feat: Expose connection params of the native client through the data service COMPASS-4517 (#277)

* feat(COMPASS-4517): Expose connection params of the native client through the data service

* refactor: Change the name from connectionParams to connectionOptions for consistency

Author: gribnoysup

lib/data-service.js

@@ -27,6 +27,10 @@ class DataService extends EventEmitter {
       .on('topologyDescriptionChanged', (evt) => this.emit('topologyDescriptionChanged', evt));
   }
 
+  getConnectionOptions() {
+    return this.client.connectionOptions;
+  }
+
   /**
    * Get the kitchen sink information about a collection.
    *

lib/native-client.js

@@ -88,6 +88,7 @@ class NativeClient extends EventEmitter {
   constructor(model) {
     super();
     this.model = model;
+    this.connectionOptions = null;
   }
 
   /**
@@ -98,25 +99,34 @@ class NativeClient extends EventEmitter {
    */
   connect(done) {
     debug('connecting...');
+
+    this.connectionOptions = null;
     this.isWritable = false;
     this.isMongos = false;
-    connect(this.model, this.setupListeners.bind(this), err => {
-      if (err) {
-        return done(this._translateMessage(err));
-      }
 
-      this.isWritable = this.client.isWritable;
-      this.isMongos = this.client.isMongos;
+    connect(
+      this.model,
+      this.setupListeners.bind(this),
+      (err, _client, connectionOptions) => {
+        if (err) {
+          return done(this._translateMessage(err));
+        }
 
-      debug('connected!', {
-        isWritable: this.isWritable,
-        isMongos: this.isMongos
-      });
+        this.connectionOptions = connectionOptions;
 
-      this.client.on('status', evt => this.emit('status', evt));
-      this.database = this.client.db(this.model.ns || ADMIN);
-      done(null, this);
-    });
+        this.isWritable = this.client.isWritable;
+        this.isMongos = this.client.isMongos;
+
+        debug('connected!', {
+          isWritable: this.isWritable,
+          isMongos: this.isMongos
+        });
+
+        this.client.on('status', (evt) => this.emit('status', evt));
+        this.database = this.client.db(this.model.ns || ADMIN);
+        done(null, this);
+      }
+    );
     return this;
   }
 

test/native-client.test.js

@@ -40,12 +40,23 @@ describe('NativeClient', function() {
 
       /*
        * pretends to be a connection-model providing every function call
-       * required in NativeClient#connect, but returns topology of our choice
+       * required in NativeClient#connect, but returns topology and connection
+       * params of our choice
        */
-      function mockedConnectionModel(topologyDescription) {
+      function mockedConnectionModel(topologyDescription, connectionOptions) {
         const _topologyDescription =
           topologyDescription || mockedTopologyDescription();
 
+        const _connectionOptions = connectionOptions || {
+          url: 'mongodb://127.0.0.1:27018/data-service?readPreference=primary&ssl=false',
+          options: {
+            connectWithNoPrimary: true,
+            readPreference: 'primary',
+            useNewUrlParser: true,
+            useUnifiedTopology: true
+          }
+        };
+
         return {
           connect(_model, setupListeners, cb) {
             const mockedClient = new EventEmitter();
@@ -54,7 +65,7 @@ describe('NativeClient', function() {
             mockedClient.emit('topologyDescriptionChanged', {
               newDescription: _topologyDescription
             });
-            cb(null, mockedClient);
+            cb(null, mockedClient, _connectionOptions);
           }
         };
       }
@@ -63,6 +74,31 @@ describe('NativeClient', function() {
         mock.stop('mongodb-connection-model');
       });
 
+      it('sets .connectionOptions after successful connection', function(done) {
+        mock(
+          'mongodb-connection-model',
+          mockedConnectionModel()
+        );
+
+        var MockedNativeClient = mock.reRequire('../lib/native-client');
+        var mockedClient = new MockedNativeClient(helper.connection);
+
+        expect(mockedClient.connectionOptions).to.be.null;
+
+        mockedClient.connect(function() {
+          expect(mockedClient.connectionOptions).to.deep.equal({
+            url: 'mongodb://127.0.0.1:27018/data-service?readPreference=primary&ssl=false',
+            options: {
+              connectWithNoPrimary: true,
+              readPreference: 'primary',
+              useNewUrlParser: true,
+              useUnifiedTopology: true
+            }
+          });
+          done();
+        });
+      });
+
       it('sets .isMongos to true when topology is sharded', function(done) {
         mock(
           'mongodb-connection-model',