diff --git a/.eslintrc b/.eslintrc
index d8301ce2..3ecca9d1 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -4,6 +4,10 @@
     "node": true,
     "es6": true
   },
+  "parserOptions": {
+    "ecmaVersion": 2018,
+    "sourceType": "module"
+  },
   "rules": {
     "strict": "off",
     "no-undef": "error",
diff --git a/lib/data-service.js b/lib/data-service.js
index d01481eb..c8321e38 100644
--- a/lib/data-service.js
+++ b/lib/data-service.js
@@ -1,4 +1,5 @@
 const EventEmitter = require('events');
+const debug = require('debug')('mongodb-data-service:data-service');
 
 /**
  * Instantiate a new DataService object.
@@ -31,6 +32,7 @@ class DataService extends EventEmitter {
       .on('topologyOpening', (evt) => this.emit('topologyOpening', evt))
       .on('topologyClosed', (evt) => this.emit('topologyClosed', evt))
       .on('topologyDescriptionChanged', (evt) => {
+        debug('got new topologyDescriptionChanged', evt.newDescription);
         this.lastSeenTopology = evt.newDescription;
         this.emit('topologyDescriptionChanged', evt);
       });
@@ -151,17 +153,13 @@ class DataService extends EventEmitter {
 
   /**
    * Connect to the server.
-   *
-   * @param {function} done - The callback function.
    */
-  connect(done) {
-    this.client.connect((err) => {
-      if (err) {
-        return done(err);
-      }
-      done(null, this);
-      this.emit('readable');
-    });
+  async connect() {
+    await this.client.connect();
+
+    this.emit('readable');
+
+    return this;
   }
 
   /**
@@ -180,6 +178,7 @@ class DataService extends EventEmitter {
    * and options.
    *
    * @param {string} ns - The namespace to search on.
+   * @param {object} filter - The filter for the count.
    * @param {object} options - The query options.
    * @param {function} callback - The callback function.
    */
diff --git a/lib/native-client.js b/lib/native-client.js
index 22af5bd0..aabce242 100644
--- a/lib/native-client.js
+++ b/lib/native-client.js
@@ -98,39 +98,37 @@ class NativeClient extends EventEmitter {
   /**
    * Connect to the server.
    *
-   * @param {function} done - The callback function.
    * @return {NativeClient}
    */
-  connect(done) {
+  async connect() {
     debug('connecting...');
 
     this.connectionOptions = null;
     this.isWritable = false;
     this.isMongos = false;
 
-    connect(
+    const [
+      // eslint-disable-next-line no-unused-vars
+      _, // The client is set in the `setupListeners` method.
+      connectionOptions
+    ] = await connect(
       this.model,
-      this.setupListeners.bind(this),
-      (err, _client, connectionOptions) => {
-        if (err) {
-          return done(this._translateMessage(err));
-        }
+      this.setupListeners.bind(this)
+    );
 
-        this.connectionOptions = connectionOptions;
+    this.connectionOptions = connectionOptions;
 
-        this.isWritable = this.client.isWritable;
-        this.isMongos = this.client.isMongos;
+    this.isWritable = this.client.isWritable;
+    this.isMongos = this.client.isMongos;
 
-        debug('connected!', {
-          isWritable: this.isWritable,
-          isMongos: this.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);
 
-        this.client.on('status', (evt) => this.emit('status', evt));
-        this.database = this.client.db(this.model.ns || ADMIN);
-        done(null, this);
-      }
-    );
     return this;
   }
 
@@ -301,7 +299,8 @@ class NativeClient extends EventEmitter {
    */
   collections(databaseName, callback) {
     if (databaseName === SYSTEM) {
-      return callback(null, []);
+      callback(null, []);
+      return;
     }
     this.collectionNames(databaseName, (error, names) => {
       if (error) {
@@ -521,6 +520,7 @@ class NativeClient extends EventEmitter {
 
   /**
    * Disconnect the client.
+   * @param {Function} callback - Callback called after connection closed.
    */
   disconnect(callback) {
     this.client.close(true, callback);
diff --git a/test/data-service.test.js b/test/data-service.test.js
index 4031009b..f792ed96 100644
--- a/test/data-service.test.js
+++ b/test/data-service.test.js
@@ -10,8 +10,8 @@ describe('DataService', function() {
   this.timeout(20000);
   const service = new DataService(helper.connection);
 
-  before(function(done) {
-    service.connect(done);
+  before(async() => {
+    await service.connect();
   });
   after(function(done) {
     service.disconnect(done);
diff --git a/test/instance-detail-helper.test.js b/test/instance-detail-helper.test.js
index 3094e8e6..485a862e 100644
--- a/test/instance-detail-helper.test.js
+++ b/test/instance-detail-helper.test.js
@@ -4,60 +4,72 @@ const connect = Connection.connect;
 const { getInstance } = require('../lib/instance-detail-helper');
 const helper = require('./helper');
 const DataService = require('../lib/data-service');
+const { promisify } = require('util');
 const _ = require('lodash');
 
 describe('mongodb-data-service#instance', function() {
   describe('local', function() {
     let client;
-    let db;
-    after(function(done) {
-      client.close(true, done);
-    });
-    it('should connect to `localhost:27018`', function(done) {
-      Connection.from(
-        'mongodb://localhost:27018/data-service',
-        function(error, model) {
-          assert.equal(error, null);
-          connect(
-            model,
-            null,
-            function(err, _client) {
-              if (err) {
-                return done(err);
-              }
-              client = _client;
-              db = client.db('data-service');
-              done();
-            }
-          );
-        }
+    let model;
+
+    before(async() => {
+      model = await Connection.from(
+        'mongodb://localhost:27018/data-service'
       );
     });
-    it('should not close the db after getting instance details', function(done) {
-      assert(db);
-      getInstance(client, db, function(err) {
-        if (err) {
-          return done(err);
-        }
-        db.admin().ping(function(_err, pingResult) {
-          if (_err) {
-            done(_err);
+
+    describe('connecting', () => {
+      after(function(done) {
+        client.close(true, done);
+      });
+      it('should connect to `localhost:27018`', async() => {
+        const [ _client ] = await connect(
+          model,
+          null
+        );
+        client = _client;
+      });
+    });
+
+    describe('after connecting', () => {
+      before(async() => {
+        const [ _client ] = await connect(
+          model,
+          null
+        );
+        client = _client;
+      });
+      after(function(done) {
+        client.close(true, done);
+      });
+
+      it('should not close the db after getting instance details', (done) => {
+        const db = client.db('data-service');
+
+        assert(db);
+        getInstance(client, db, function(err) {
+          if (err) {
+            return done(err);
           }
-          done(null, pingResult);
+          db.admin().ping(function(_err, pingResult) {
+            if (_err) {
+              done(_err);
+            }
+            done(null, pingResult);
+          });
         });
       });
     });
+
     if (process.env.MONGODB_TOPOLOGY !== 'cluster') {
       describe('views', function() {
-        var service = new DataService(helper.connection);
-        var instanceDetails = null;
-        before(function(done) {
-          service.connect(function(err) {
-            if (err) return done(err);
-            helper.insertTestDocuments(service.client, function() {
-              done();
-            });
-          });
+        const service = new DataService(helper.connection);
+        let instanceDetails;
+        before(async() => {
+          await service.connect();
+
+          const runInsertDocuments = promisify(helper.insertTestDocuments);
+          await runInsertDocuments(service.client);
         });
 
         after(function(done) {
diff --git a/test/native-client.test.js b/test/native-client.test.js
index e98e0f1e..ed909b61 100644
--- a/test/native-client.test.js
+++ b/test/native-client.test.js
@@ -1,25 +1,23 @@
-var sinon = require('sinon');
-var helper = require('./helper');
-var assert = helper.assert;
-var expect = helper.expect;
-var ObjectId = require('bson').ObjectId;
-var mock = require('mock-require');
+const sinon = require('sinon');
+const helper = require('./helper');
+const assert = helper.assert;
+const expect = helper.expect;
+const ObjectId = require('bson').ObjectId;
+const mock = require('mock-require');
 const EventEmitter = require('events');
 
-var NativeClient = require('../lib/native-client');
+const NativeClient = require('../lib/native-client');
 
 describe('NativeClient', function() {
   this.slow(10000);
   this.timeout(20000);
-  var client = new NativeClient(helper.connection);
-
-  before(function(done) {
-    const callback = (err, result) => {
-      const adminDb = client.database.admin();
-      adminDb.addUser('dba-admin', 'password', { roles: ['root'] });
-      done(err, result);
-    };
-    client.connect(callback);
+  const client = new NativeClient(helper.connection);
+
+  before(async() => {
+    await client.connect();
+
+    const adminDb = client.database.admin();
+    adminDb.addUser('dba-admin', 'password', { roles: ['root'] });
   });
 
   after(function(done) {
@@ -64,14 +62,18 @@ describe('NativeClient', function() {
         };
 
         return {
-          connect(_model, setupListeners, cb) {
+          async connect(_model, setupListeners) {
             const mockedClient = new EventEmitter();
             mockedClient.db = () => {};
             setupListeners(mockedClient);
             mockedClient.emit('topologyDescriptionChanged', {
               newDescription: _topologyDescription
             });
-            cb(null, mockedClient, _connectionOptions);
+
+            return [
+              mockedClient,
+              _connectionOptions
+            ];
           }
         };
       }
@@ -80,59 +82,54 @@ describe('NativeClient', function() {
         mock.stop('mongodb-connection-model');
       });
 
-      it('sets .connectionOptions after successful connection', function(done) {
+      it('sets .connectionOptions after successful connection', async() => {
         mock(
           'mongodb-connection-model',
           mockedConnectionModel()
         );
 
-        var MockedNativeClient = mock.reRequire('../lib/native-client');
-        var mockedClient = new MockedNativeClient(helper.connection);
+        const MockedNativeClient = mock.reRequire('../lib/native-client');
+        const 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();
+        await mockedClient.connect();
+
+        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
+          }
         });
       });
 
-      it('sets .isMongos to true when topology is sharded', function(done) {
+      it('sets .isMongos to true when topology is sharded', async() => {
         mock(
           'mongodb-connection-model',
           mockedConnectionModel(mockedTopologyDescription('Sharded'))
         );
 
-        var MockedNativeClient = mock.reRequire('../lib/native-client');
-        var mockedClient = new MockedNativeClient(helper.connection);
+        const MockedNativeClient = mock.reRequire('../lib/native-client');
+        const mockedClient = new MockedNativeClient(helper.connection);
 
-        mockedClient.connect(function() {
-          expect(mockedClient.isMongos).to.be.true;
-          done();
-        });
+        await mockedClient.connect();
+        expect(mockedClient.isMongos).to.be.true;
       });
 
-      it('sets .isMongos to false when topology is not sharded', function(done) {
+      it('sets .isMongos to false when topology is not sharded', async() => {
         mock('mongodb-connection-model', mockedConnectionModel());
 
-        var MockedNativeClient = mock.reRequire('../lib/native-client');
-        var mockedClient = new MockedNativeClient(helper.connection);
+        const MockedNativeClient = mock.reRequire('../lib/native-client');
+        const mockedClient = new MockedNativeClient(helper.connection);
 
-        mockedClient.connect(function() {
-          expect(mockedClient.isMongos).to.be.false;
-          done();
-        });
+        await mockedClient.connect();
+        expect(mockedClient.isMongos).to.be.false;
       });
 
-      it('sets .isWritable to true when the node is a primary replset member', function(done) {
+      it('sets .isWritable to true when the node is a primary replset member', async() => {
         mock(
           'mongodb-connection-model',
           mockedConnectionModel(
@@ -143,13 +140,11 @@ describe('NativeClient', function() {
         var MockedNativeClient = mock.reRequire('../lib/native-client');
         var mockedClient = new MockedNativeClient(helper.connection);
 
-        mockedClient.connect(function() {
-          expect(mockedClient.isWritable).to.be.true;
-          done();
-        });
+        await mockedClient.connect();
+        expect(mockedClient.isWritable).to.be.true;
       });
 
-      it('sets .isWritable to false when the node is a secondary replset member', function(done) {
+      it('sets .isWritable to false when the node is a secondary replset member', async() => {
         mock(
           'mongodb-connection-model',
           mockedConnectionModel(
@@ -160,13 +155,11 @@ describe('NativeClient', function() {
         var MockedNativeClient = mock.reRequire('../lib/native-client');
         var mockedClient = new MockedNativeClient(helper.connection);
 
-        mockedClient.connect(function() {
-          expect(mockedClient.isWritable).to.be.false;
-          done();
-        });
+        await mockedClient.connect();
+        expect(mockedClient.isWritable).to.be.false;
       });
 
-      it('sets .isWritable to true when the node is a mongos', function(done) {
+      it('sets .isWritable to true when the node is a mongos', async() => {
         mock(
           'mongodb-connection-model',
           mockedConnectionModel(mockedTopologyDescription('Single', 'Mongos'))
@@ -175,10 +168,8 @@ describe('NativeClient', function() {
         var MockedNativeClient = mock.reRequire('../lib/native-client');
         var mockedClient = new MockedNativeClient(helper.connection);
 
-        mockedClient.connect(function() {
-          expect(mockedClient.isWritable).to.be.true;
-          done();
-        });
+        await mockedClient.connect();
+        expect(mockedClient.isWritable).to.be.true;
       });
     });
   });
@@ -555,10 +546,6 @@ describe('NativeClient', function() {
         });
       });
     });
-
-    context('when the user is not authorized', function() {
-      it('passes an error to the callback');
-    });
   });
 
   describe('#estimatedCount', function() {