Add LoadState method to Program and write some unit tests in ProgramT…

…ests.

csharp/BrainmessShort/BrainmessShort.csproj

@@ -65,6 +65,7 @@
     <Compile Include="StringExtensions.cs" />
     <Compile Include="StringExtensionsTests.cs" />
     <Compile Include="Program.cs" />
+    <Compile Include="ProgramTests.cs" />
   </ItemGroup>
   <ItemGroup>
     <BootstrapperPackage Include="Microsoft.Net.Client.3.5">

csharp/BrainmessShort/Program.cs

@@ -13,6 +13,13 @@ public Program(string program)
             pc = 0;
         }
 
+        public static Program LoadState(string programString, int pc)
+        {
+            Program program = new Program(programString);
+            program.pc = pc;
+            return program;
+        }
+
         public bool EndOfProgram
         {
             get

csharp/BrainmessShort/ProgramTests.cs

@@ -0,0 +1,60 @@
+using System;
+using NUnit.Framework;
+namespace BrainmessShort
+{
+    [TestFixture]
+    public class ProgramStreamTests
+    {
+        // White box testing. Each method only needs one test because there are no alternative paths.
+        // The "hard" testing is done for StringExtensions.FindMatch
+
+
+        [Test]
+        public void JumpForward()
+        {
+            // Arrange
+            //                                   0123456789
+            Program program = Program.LoadState("++[     ]   ", 3);
+
+            // Act
+            program.JumpForward();
+
+            // Assert
+            Assert.AreEqual(9, program.ProgramCounter);
+
+        }
+
+        [Test]
+        public void JumpBackward()
+        {
+            // Arrange
+            //                                   0123456789
+            Program program = Program.LoadState("++[     ]   ", 9);
+
+            // Act
+            program.JumpBackward();
+
+            // Assert
+            Assert.AreEqual(2, program.ProgramCounter);
+        }
+
+        [Test]
+        public void Fetch__ShouldReturnNextInstruction()
+        {
+            // Arrange
+            //                                   0123456789
+            Program program = Program.LoadState("++[>>.>>>abc]   ", 4);
+
+            // Act
+            var instruction = program.Fetch();
+
+            // Assert
+            Assert.AreEqual('>', instruction);
+        }
+
+    }
+
+}
+
+
+