Fix tests.

Author: JohanLarsson

….Tests/Helpers/StringLiteralSpanTests.cs …CoreAnalyzers.Tests/Helpers/SpanTests.csAspNetCoreAnalyzers.Tests/Helpers/StringLiteralSpanTests.cs renamed to AspNetCoreAnalyzers.Tests/Helpers/SpanTests.cs AspNetCoreAnalyzers.Tests/Helpers/StringLiteralSpanTests.cs renamed to AspNetCoreAnalyzers.Tests/Helpers/SpanTests.cs

@@ -5,11 +5,13 @@ namespace AspNetCoreAnalyzers.Tests.Helpers
     using Microsoft.CodeAnalysis.CSharp;
     using NUnit.Framework;
 
-    public class StringLiteralSpanTests
+    public class SpanTests
     {
-        [TestCase("\"abc\"", "abc", true)]
-        [TestCase("\"abc\"", "ab", false)]
-        [TestCase("\"abc\"", "bc", false)]
+        [TestCase("\"abc\"", "abc",  true)]
+        [TestCase("\"abc\"", "ab",   false)]
+        [TestCase("\"abc\"", "bc",   false)]
+        [TestCase("\"abc\"", "a",    false)]
+        [TestCase("\"abc\"", "abcd", false)]
         public void Equals(string text, string value, bool expected)
         {
             var syntaxTree = CSharpSyntaxTree.ParseText(@"
@@ -28,10 +30,11 @@ class C
             Assert.AreEqual(expected, span.Equals(value, StringComparison.Ordinal));
         }
 
-        [TestCase("\"abc\"", "abc", true)]
-        [TestCase("\"abc\"", "ab",  true)]
-        [TestCase("\"abc\"", "a",  true)]
-        [TestCase("\"abc\"", "bc",  false)]
+        [TestCase("\"abc\"", "abc",  true)]
+        [TestCase("\"abc\"", "ab",   true)]
+        [TestCase("\"abc\"", "a",    true)]
+        [TestCase("\"abc\"", "bc",   false)]
+        [TestCase("\"abc\"", "abcd", false)]
         public void StartsWith(string text, string value, bool expected)
         {
             var syntaxTree = CSharpSyntaxTree.ParseText(@"
@@ -50,10 +53,12 @@ class C
             Assert.AreEqual(expected, span.StartsWith(value, StringComparison.Ordinal));
         }
 
-        [TestCase("\"abc\"", "abc", true)]
-        [TestCase("\"abc\"", "bc",  true)]
-        [TestCase("\"abc\"", "c",   true)]
-        [TestCase("\"abc\"", "ab",  false)]
+        [TestCase("\"abc\"", "abc",  true)]
+        [TestCase("\"abc\"", "bc",   true)]
+        [TestCase("\"abc\"", "c",    true)]
+        [TestCase("\"abc\"", "ab",   false)]
+        [TestCase("\"abc\"", "bc",   false)]
+        [TestCase("\"abc\"", "dabc", false)]
         public void EndsWith(string text, string value, bool expected)
         {
             var syntaxTree = CSharpSyntaxTree.ParseText(@"

AspNetCoreAnalyzers/Helpers/Span.cs

@@ -115,13 +115,20 @@ internal bool Equals(string value, StringComparison comparisonType)
 
         internal bool StartsWith(string value, StringComparison comparisonType)
         {
-            return this.Literal.ValueText.IndexOf(value, this.TextSpan.Start, value.Length, comparisonType) == this.TextSpan.Start;
+            return this.Length >= value.Length &&
+                   this.Literal.ValueText.IndexOf(value, this.TextSpan.Start, value.Length, comparisonType) == this.TextSpan.Start;
         }
 
         internal bool EndsWith(string value, StringComparison comparisonType)
         {
-            var start = this.TextSpan.End - value.Length;
-            return this.Literal.ValueText.IndexOf(value, start, value.Length, comparisonType) == start;
+            if (this.Length >= value.Length)
+            {
+                var start = this.TextSpan.End - value.Length;
+                return this.Literal.ValueText.IndexOf(value, start, value.Length, comparisonType) == start;
+            }
+
+
+            return false;
         }
     }
 }