Fixing bad data issue w/closing/opening untitled doc (#142)

* Adding useful unit tests for this functionality
* Adding callback functionality for when a file is closed

* Fixing bad data issue w/closing/opening untitled doc

* Adding useful unit tests for this functionality
* Adding callback functionality for when a file is closed

* Moving from public to internal

test/Microsoft.SqlTools.ServiceLayer.Test/Workspace/WorkspaceTests.cs

@@ -0,0 +1,94 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System.IO;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol;
+using Microsoft.SqlTools.ServiceLayer.SqlContext;
+using Microsoft.SqlTools.ServiceLayer.Workspace;
+using Microsoft.SqlTools.ServiceLayer.Workspace.Contracts;
+using Microsoft.SqlTools.Test.Utility;
+using Moq;
+using Xunit;
+
+namespace Microsoft.SqlTools.ServiceLayer.Test.Workspace
+{
+    public class WorkspaceTests
+    {
+        [Fact]
+        public async Task FileClosedSuccessfully()
+        {
+            // Given:
+            // ... A workspace that has a single file open
+            var workspace = new ServiceLayer.Workspace.Workspace();
+            var workspaceService = new WorkspaceService<SqlToolsSettings> {Workspace = workspace};
+            var openedFile = workspace.GetFileBuffer(TestObjects.ScriptUri, string.Empty);
+            Assert.NotNull(openedFile);
+            Assert.NotEmpty(workspace.GetOpenedFiles());
+
+            // ... And there is a callback registered for the file closed event
+            ScriptFile closedFile = null;
+            workspaceService.RegisterTextDocCloseCallback((f, c) =>
+            {
+                closedFile = f;
+                return Task.FromResult(true);
+            });
+
+            // If:
+            // ... An event to close the open file occurs
+            var eventContext = new Mock<EventContext>().Object;
+            var requestParams = new DidCloseTextDocumentParams
+            {
+                TextDocument = new TextDocumentItem {Uri = TestObjects.ScriptUri}
+            };
+            await workspaceService.HandleDidCloseTextDocumentNotification(requestParams, eventContext);
+
+            // Then:
+            // ... The file should no longer be in the open files
+            Assert.Empty(workspace.GetOpenedFiles());
+
+            // ... The callback should have been called
+            // ... The provided script file should be the one we created
+            Assert.NotNull(closedFile);
+            Assert.Equal(openedFile, closedFile);
+        }
+
+        [Fact]
+        public async Task FileClosedNotOpen()
+        {
+            // Given:
+            // ... A workspace that has no files open
+            var workspace = new ServiceLayer.Workspace.Workspace();
+            var workspaceService = new WorkspaceService<SqlToolsSettings> {Workspace = workspace};
+            Assert.Empty(workspace.GetOpenedFiles());
+
+            // ... And there is a callback registered for the file closed event
+            bool callbackCalled = false;
+            workspaceService.RegisterTextDocCloseCallback((f, c) =>
+            {
+                callbackCalled = true;
+                return Task.FromResult(true);
+            });
+
+            // If:
+            // ... An event to close the a file occurs
+            var eventContext = new Mock<EventContext>().Object;
+            var requestParams = new DidCloseTextDocumentParams
+            {
+                TextDocument = new TextDocumentItem {Uri = TestObjects.ScriptUri}
+            };
+            // Then:
+            // ... There should be a file not found exception thrown
+            // TODO: This logic should be changed to not create the ScriptFile
+            await Assert.ThrowsAsync<IOException>(
+                () => workspaceService.HandleDidCloseTextDocumentNotification(requestParams, eventContext));
+
+            // ... There should still be no open files
+            // ... The callback should not have been called
+            Assert.Empty(workspace.GetOpenedFiles());
+            Assert.False(callbackCalled);
+        }
+    }
+}