diff --git a/src/Microsoft.SqlTools.ServiceLayer/LanguageServices/AutoCompleteService.cs b/src/Microsoft.SqlTools.ServiceLayer/LanguageServices/AutoCompleteService.cs
index 616fc2c6..a390eae2 100644
--- a/src/Microsoft.SqlTools.ServiceLayer/LanguageServices/AutoCompleteService.cs
+++ b/src/Microsoft.SqlTools.ServiceLayer/LanguageServices/AutoCompleteService.cs
@@ -80,13 +80,36 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
                 }
             }
         }
+
+        private ConnectionService connectionService = null;
+
+        /// <summary>
+        /// Internal for testing purposes only
+        /// </summary>
+        internal ConnectionService ConnectionServiceInstance
+        {
+            get
+            {
+                if(connectionService == null)
+                {
+                    connectionService = ConnectionService.Instance;
+                }
+                return connectionService;
+            }
+
+            set
+            {
+                connectionService = value;
+            }
+        }
+
         public void InitializeService(ServiceHost serviceHost)
         {
             // Register a callback for when a connection is created
-            ConnectionService.Instance.RegisterOnConnectionTask(UpdateAutoCompleteCache);
+            ConnectionServiceInstance.RegisterOnConnectionTask(UpdateAutoCompleteCache);
 
             // Register a callback for when a connection is closed
-            ConnectionService.Instance.RegisterOnDisconnectTask(RemoveAutoCompleteCacheUriReference);
+            ConnectionServiceInstance.RegisterOnDisconnectTask(RemoveAutoCompleteCacheUriReference);
         }
 
         private async Task UpdateAutoCompleteCache(ConnectionInfo connectionInfo)
@@ -97,6 +120,14 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             }
         }
 
+        /// <summary>
+        /// Intellisense cache count access for testing.
+        /// </summary>
+        internal int GetCacheCount()
+        {
+            return caches.Count;
+        }
+
         /// <summary>
         /// Remove a reference to an autocomplete cache from a URI. If
         /// it is the last URI connected to a particular connection,
@@ -157,7 +188,7 @@ namespace Microsoft.SqlTools.ServiceLayer.LanguageServices
             // that are not backed by a SQL connection
             ConnectionInfo info;
             IntellisenseCache cache;
-            if (ConnectionService.Instance.TryFindConnection(textDocumentPosition.Uri, out info)
+            if (ConnectionServiceInstance.TryFindConnection(textDocumentPosition.Uri, out info)
                 && caches.TryGetValue((ConnectionSummary)info.ConnectionDetails, out cache))
             {
                 return cache.GetAutoCompleteItems(textDocumentPosition).ToArray();
diff --git a/test/Microsoft.SqlTools.ServiceLayer.Test/LanguageServer/LanguageServiceTests.cs b/test/Microsoft.SqlTools.ServiceLayer.Test/LanguageServer/LanguageServiceTests.cs
index 80ea3ec9..ddf82059 100644
--- a/test/Microsoft.SqlTools.ServiceLayer.Test/LanguageServer/LanguageServiceTests.cs
+++ b/test/Microsoft.SqlTools.ServiceLayer.Test/LanguageServer/LanguageServiceTests.cs
@@ -3,11 +3,18 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 //
 
+using System.Collections.Generic;
+using System.Data;
+using System.Data.Common;
 using System.Threading.Tasks;
 using Microsoft.SqlTools.ServiceLayer.Connection;
+using Microsoft.SqlTools.ServiceLayer.Connection.Contracts;
 using Microsoft.SqlTools.ServiceLayer.LanguageServices;
+using Microsoft.SqlTools.ServiceLayer.Test.Utility;
 using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;
 using Microsoft.SqlTools.Test.Utility;
+using Moq;
+using Moq.Protected;
 using Xunit;
 
 namespace Microsoft.SqlTools.ServiceLayer.Test.LanguageServices
@@ -19,6 +26,29 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.LanguageServices
     {
         #region "Diagnostics tests"
 
+        /// <summary>
+        /// Verify that the latest SqlParser (2016 as of this writing) is used by default
+        /// </summary>
+        [Fact]
+        public void LatestSqlParserIsUsedByDefault()
+        {
+            // This should only parse correctly on SQL server 2016 or newer
+            const string sql2016Text = 
+                @"CREATE SECURITY POLICY [FederatedSecurityPolicy]" + "\r\n" +
+                @"ADD FILTER PREDICATE [rls].[fn_securitypredicate]([CustomerId])" + "\r\n" +   
+                @"ON [dbo].[Customer];";
+            
+            LanguageService service = TestObjects.GetTestLanguageService();
+
+            // parse
+            var scriptFile = new ScriptFile();
+            scriptFile.SetFileContents(sql2016Text);
+            ScriptFileMarker[] fileMarkers = service.GetSemanticMarkers(scriptFile);
+
+            // verify that no errors are detected
+            Assert.Equal(0, fileMarkers.Length);
+        }
+
         /// <summary>
         /// Verify that the SQL parser correctly detects errors in text
         /// </summary>
@@ -108,24 +138,179 @@ namespace Microsoft.SqlTools.ServiceLayer.Test.LanguageServices
         #region "Autocomplete Tests"
 
         /// <summary>
-        /// Verify that the SQL parser correctly detects errors in text
+        /// Creates a mock db command that returns a predefined result set
+        /// </summary>
+        public static DbCommand CreateTestCommand(Dictionary<string, string>[][] data)
+        {
+            var commandMock = new Mock<DbCommand> { CallBase = true };
+            var commandMockSetup = commandMock.Protected()
+                .Setup<DbDataReader>("ExecuteDbDataReader", It.IsAny<CommandBehavior>());
+
+            commandMockSetup.Returns(new TestDbDataReader(data));
+
+            return commandMock.Object;
+        }
+
+        /// <summary>
+        /// Creates a mock db connection that returns predefined data when queried for a result set
+        /// </summary>
+        public DbConnection CreateMockDbConnection(Dictionary<string, string>[][] data)
+        {
+            var connectionMock = new Mock<DbConnection> { CallBase = true };
+            connectionMock.Protected()
+                .Setup<DbCommand>("CreateDbCommand")
+                .Returns(CreateTestCommand(data));
+
+            return connectionMock.Object;
+        }
+
+        /// <summary>
+        /// Verify that the autocomplete service returns tables for the current connection as suggestions
         /// </summary>
         [Fact]
-        public async Task AutocompleteTest()
+        public void TablesAreReturnedAsAutocompleteSuggestions()
         {
-            // TODO Re-enable this test once we have a way to hook up the right auto-complete and connection services.
-            // Probably need a service provider channel so that we can mock service access. Otherwise everything accesses
-            // static instances and cannot be properly tested.
-             
-            //var autocompleteService = TestObjects.GetAutoCompleteService();
-            //var connectionService = TestObjects.GetTestConnectionService();
+            // Result set for the query of database tables
+            Dictionary<string, string>[] data =
+            {
+                new Dictionary<string, string> { {"name", "master" } },
+                new Dictionary<string, string> { {"name", "model" } }
+            };
 
-            //ConnectParams connectionRequest = TestObjects.GetTestConnectionParams();
-            //var connectionResult = connectionService.Connect(connectionRequest);
+            var mockFactory = new Mock<ISqlConnectionFactory>();
+            mockFactory.Setup(factory => factory.CreateSqlConnection(It.IsAny<string>()))
+                .Returns(CreateMockDbConnection(new[] {data}));
+
+            var connectionService = TestObjects.GetTestConnectionService();
+            var autocompleteService = new AutoCompleteService();
+            autocompleteService.ConnectionServiceInstance = connectionService;
+            autocompleteService.InitializeService(Microsoft.SqlTools.ServiceLayer.Hosting.ServiceHost.Instance);
+
+            autocompleteService.ConnectionFactory = mockFactory.Object;
             
-            //var sqlConnection = connectionService.ActiveConnections[connectionResult.ConnectionId];
-            //await autocompleteService.UpdateAutoCompleteCache(sqlConnection);
-            await Task.Run(() => { return; });
+            // Open a connection
+            // The cache should get updated as part of this
+            ConnectParams connectionRequest = TestObjects.GetTestConnectionParams();
+            var connectionResult = connectionService.Connect(connectionRequest);
+            Assert.NotEmpty(connectionResult.ConnectionId);
+
+            // Check that there is one cache created in the auto complete service
+            Assert.Equal(1, autocompleteService.GetCacheCount());
+
+            // Check that we get table suggestions for an autocomplete request
+            TextDocumentPosition position = new TextDocumentPosition();
+            position.Uri = connectionRequest.OwnerUri;
+            position.Position = new Position();
+            position.Position.Line = 1;
+            position.Position.Character = 1;
+            var items = autocompleteService.GetCompletionItems(position);
+            Assert.Equal(2, items.Length);
+            Assert.Equal("master", items[0].Label);
+            Assert.Equal("model", items[1].Label);
+        }
+
+        /// <summary>
+        /// Verify that only one intellisense cache is created for two documents using
+        /// the autocomplete service when they share a common connection.
+        /// </summary>
+        [Fact]
+        public void OnlyOneCacheIsCreatedForTwoDocumentsWithSameConnection()
+        {
+            var connectionService = TestObjects.GetTestConnectionService();
+            var autocompleteService = new AutoCompleteService();
+            autocompleteService.ConnectionServiceInstance = connectionService;
+            autocompleteService.InitializeService(Microsoft.SqlTools.ServiceLayer.Hosting.ServiceHost.Instance);
+
+            // Open two connections
+            ConnectParams connectionRequest1 = TestObjects.GetTestConnectionParams();
+            connectionRequest1.OwnerUri = "file:///my/first/file.sql";
+            ConnectParams connectionRequest2 = TestObjects.GetTestConnectionParams();
+            connectionRequest2.OwnerUri = "file:///my/second/file.sql";
+            var connectionResult1 = connectionService.Connect(connectionRequest1);
+            Assert.NotEmpty(connectionResult1.ConnectionId);
+            var connectionResult2 = connectionService.Connect(connectionRequest2);
+            Assert.NotEmpty(connectionResult2.ConnectionId);
+
+            // Verify that only one intellisense cache is created to service both URI's
+            Assert.Equal(1, autocompleteService.GetCacheCount());
+        }
+
+        /// <summary>
+        /// Verify that two different intellisense caches and corresponding autocomplete
+        /// suggestions are provided for two documents with different connections.
+        /// </summary>
+        [Fact]
+        public void TwoCachesAreCreatedForTwoDocumentsWithDifferentConnections()
+        {
+            // Result set for the query of database tables
+            Dictionary<string, string>[] data1 =
+            {
+                new Dictionary<string, string> { {"name", "master" } },
+                new Dictionary<string, string> { {"name", "model" } }
+            };
+
+            Dictionary<string, string>[] data2 =
+            {
+                new Dictionary<string, string> { {"name", "master" } },
+                new Dictionary<string, string> { {"name", "my_table" } },
+                new Dictionary<string, string> { {"name", "my_other_table" } }
+            };
+
+            var mockFactory = new Mock<ISqlConnectionFactory>();
+            mockFactory.SetupSequence(factory => factory.CreateSqlConnection(It.IsAny<string>()))
+                .Returns(CreateMockDbConnection(new[] {data1}))
+                .Returns(CreateMockDbConnection(new[] {data2}));
+
+            var connectionService = TestObjects.GetTestConnectionService();
+            var autocompleteService = new AutoCompleteService();
+            autocompleteService.ConnectionServiceInstance = connectionService;
+            autocompleteService.InitializeService(Microsoft.SqlTools.ServiceLayer.Hosting.ServiceHost.Instance);
+
+            autocompleteService.ConnectionFactory = mockFactory.Object;
+            
+            // Open connections
+            // The cache should get updated as part of this
+            ConnectParams connectionRequest = TestObjects.GetTestConnectionParams();
+            connectionRequest.OwnerUri = "file:///my/first/sql/file.sql";
+            var connectionResult = connectionService.Connect(connectionRequest);
+            Assert.NotEmpty(connectionResult.ConnectionId);
+
+            // Check that there is one cache created in the auto complete service
+            Assert.Equal(1, autocompleteService.GetCacheCount());
+
+            // Open second connection
+            ConnectParams connectionRequest2 = TestObjects.GetTestConnectionParams();
+            connectionRequest2.OwnerUri = "file:///my/second/sql/file.sql";
+            connectionRequest2.Connection.DatabaseName = "my_other_db";
+            var connectionResult2 = connectionService.Connect(connectionRequest2);
+            Assert.NotEmpty(connectionResult2.ConnectionId);
+
+            // Check that there are now two caches in the auto complete service
+            Assert.Equal(2, autocompleteService.GetCacheCount());
+
+            // Check that we get 2 different table suggestions for autocomplete requests
+            TextDocumentPosition position = new TextDocumentPosition();
+            position.Uri = connectionRequest.OwnerUri;
+            position.Position = new Position();
+            position.Position.Line = 1;
+            position.Position.Character = 1;
+
+            var items = autocompleteService.GetCompletionItems(position);
+            Assert.Equal(2, items.Length);
+            Assert.Equal("master", items[0].Label);
+            Assert.Equal("model", items[1].Label);
+
+            TextDocumentPosition position2 = new TextDocumentPosition();
+            position2.Uri = connectionRequest2.OwnerUri;
+            position2.Position = new Position();
+            position2.Position.Line = 1;
+            position2.Position.Character = 1;
+            
+            var items2 = autocompleteService.GetCompletionItems(position2);
+            Assert.Equal(3, items2.Length);
+            Assert.Equal("master", items2[0].Label);
+            Assert.Equal("my_table", items2[1].Label);
+            Assert.Equal("my_other_table", items2[2].Label);
         }
 
         #endregion