Implement test code analyzer

ScriptCoreGenerator.Test/MakeConstUnitTests.cs

@@ -0,0 +1,49 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Threading.Tasks;
+using VerifyCS = MakeConst.Test.CSharpCodeFixVerifier<
+    ScriptCoreGenerator.StyleChecker,
+    ScriptCoreGenerator.MakeConstCodeFixProvider>;
+
+namespace MakeConst.Test
+{
+    [TestClass]
+    public class MakeConstUnitTest
+    {
+        //No diagnostics expected to show up
+        [TestMethod]
+        public async Task TestEmpty()
+        {
+            var test = @"";
+
+            await VerifyCS.VerifyAnalyzerAsync(test);
+        }
+
+        [TestMethod]
+        public async Task LocalIntCouldBeConstant_Diagnostic()
+        {
+            await VerifyCS.VerifyCodeFixAsync(@"
+using System;
+
+class Program
+{
+    static void Main()
+    {
+        [|int i = 0;|]
+        Console.WriteLine(i);
+    }
+}
+", @"
+using System;
+
+class Program
+{
+    static void Main()
+    {
+        const int i = 0;
+        Console.WriteLine(i);
+    }
+}
+");
+        }
+    }
+}