Add integration AssignPatternTest

Lox.Compiler.Tests/Integration/Lexing/Patterns/AssignPatternTest.cs

@@ -0,0 +1,54 @@
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Lox.Compiler.Lexing;
+using Lox.Compiler.Tests.Common;
+
+namespace Lox.Compiler.Tests.Integration.Lexing.Patterns
+{
+    [TestClass]
+    public sealed class AssignPatternTest
+    {
+        [TestMethod]
+        public void TestSingle()
+        {
+            var file = string.Empty;
+            var source = "=";
+
+            var truthTokens = new Token[]
+            {
+                new Token(file, 0, TokenType.ASSIGN, string.Empty),
+                new Token(file, 1, TokenType.END_OF_FILE, string.Empty)
+            };
+            var truthSourcemap = new SourcePosition[]
+            {
+                new SourcePosition(file, 0, 1, 1),
+                new SourcePosition(file, 1, 1, 2)
+            };
+
+            LexingTestHelper.AssertScanner(source, truthTokens, truthSourcemap);
+        }
+
+        [TestMethod]
+        public void TestSurrounded()
+        {
+            var file = string.Empty;
+            var source = " = ";
+
+            var truthTokens = new Token[]
+            {
+                new Token(file, 0, TokenType.WHITESPACE, string.Empty),
+                new Token(file, 1, TokenType.ASSIGN, string.Empty),
+                new Token(file, 2, TokenType.WHITESPACE, string.Empty),
+                new Token(file, 3, TokenType.END_OF_FILE, string.Empty)
+            };
+            var truthSourcemap = new SourcePosition[]
+            {
+                new SourcePosition(file, 0, 1, 1),
+                new SourcePosition(file, 1, 1, 2),
+                new SourcePosition(file, 2, 1, 3),
+                new SourcePosition(file, 3, 1, 4)
+            };
+
+            LexingTestHelper.AssertScanner(source, truthTokens, truthSourcemap);
+        }
+    }
+}

Lox.Compiler/Lexing/TextHelper.cs

@@ -35,6 +35,11 @@ public bool IsAtEnd(string source, int index)
 
         public bool IsMatchChar(string source, int index, char target)
         {
+            if (this.IsAtEnd(source, index))
+            {
+                return false;
+            }
+
             return source[index] == target;
         }