Unit tests for the message reader

test/Microsoft.SqlTools.ServiceLayer.Test/Messaging/MessageWriterTests.cs

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+//
+// 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.Text;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol;
+using Microsoft.SqlTools.ServiceLayer.Hosting.Protocol.Serializers;
+using Xunit;
+
+namespace Microsoft.SqlTools.ServiceLayer.Test.Messaging
+{
+    public class MessageWriterTests
+    {
+        private readonly IMessageSerializer messageSerializer;
+
+        public MessageWriterTests()
+        {
+            this.messageSerializer = new V8MessageSerializer();
+        }
+
+        [Fact]
+        public async Task WritesMessage()
+        {
+            MemoryStream outputStream = new MemoryStream();
+            MessageWriter messageWriter = new MessageWriter(outputStream, this.messageSerializer);
+
+            // Write the message and then roll back the stream to be read
+            // TODO: This will need to be redone!
+            await messageWriter.WriteMessage(Hosting.Protocol.Contracts.Message.Event("testEvent", null));
+            outputStream.Seek(0, SeekOrigin.Begin);
+
+            string expectedHeaderString = string.Format(Constants.ContentLengthFormatString,
+                Common.ExpectedMessageByteCount);
+
+            byte[] buffer = new byte[128];
+            await outputStream.ReadAsync(buffer, 0, expectedHeaderString.Length);
+
+            Assert.Equal(
+                expectedHeaderString,
+                Encoding.ASCII.GetString(buffer, 0, expectedHeaderString.Length));
+
+            // Read the message
+            await outputStream.ReadAsync(buffer, 0, Common.ExpectedMessageByteCount);
+
+            Assert.Equal(Common.TestEventString, 
+                Encoding.UTF8.GetString(buffer, 0, Common.ExpectedMessageByteCount));
+
+            outputStream.Dispose();
+        }
+
+    }
+}