Null pointer fixed in PathMatch

Fixes #51

Additionally removes a minor allocation source via the use of the PathComparisonUtility

Author: Turnerj

src/TurnerSoftware.RobotsExclusionTools/Helpers/PathComparisonUtility.cs

@@ -1,13 +1,11 @@
 using System;
-using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 
 namespace TurnerSoftware.RobotsExclusionTools.Helpers
 {
-	public class PathComparisonUtility
+	public static class PathComparisonUtility
 	{
-		public bool IsAllowed(SiteAccessEntry accessEntry, Uri requestUri)
+		public static bool IsAllowed(SiteAccessEntry accessEntry, Uri requestUri)
 		{
 			var requestPath = requestUri.PathAndQuery;
 
@@ -38,14 +36,14 @@ public bool IsAllowed(SiteAccessEntry accessEntry, Uri requestUri)
 			return true;
 		}
 
-		public bool PathMatch(string sourceRecord, string uriPath, StringComparison comparison)
+		public static bool PathMatch(string sourceRecord, string uriPath, StringComparison comparison)
 		{
 			var sourcePieces = sourceRecord.Split(new[] { '*' }, StringSplitOptions.RemoveEmptyEntries).ToArray();
 			var lastPiece = sourcePieces.LastOrDefault();
 			var mustMatchToEnd = false;
 			var mustMatchToStart = true;
 
-			if (lastPiece.EndsWith("$"))
+			if (lastPiece != null && lastPiece.EndsWith("$"))
 			{
 				//Remove the last dollar sign from the last piece
 				lastPiece = lastPiece.Substring(0, lastPiece.Length - 1);

src/TurnerSoftware.RobotsExclusionTools/RobotsFile.cs

@@ -53,8 +53,7 @@ public bool IsAllowedAccess(Uri uri, string userAgent)
 			}
 
 			var entry = GetEntryForUserAgent(userAgent);
-			var pathComparisonUtility = new PathComparisonUtility();
-			return pathComparisonUtility.IsAllowed(entry, uri);
+			return PathComparisonUtility.IsAllowed(entry, uri);
 		}
 
 		public SiteAccessEntry GetEntryForUserAgent(string userAgent)

tests/TurnerSoftware.RobotsExclusionTools.Tests/Resources/RobotsFile/Comprehensive-Example.txt

@@ -36,6 +36,10 @@ Disallow: /org/plan.html
 User-agent: PathMustEndWith
 Disallow: /org/plan.html$
 Disallow: /org/planb.html*$
+
+User-agent: OnlyWildcard
+Disallow: /org/plan.html
+Allow: *
 
 Sitemap: http://www.example.org/sitemap2.xml
 

tests/TurnerSoftware.RobotsExclusionTools.Tests/RobotsFile/PathWildcardTests.cs

@@ -97,5 +97,20 @@ public void PathMustEndWith()
 			Assert.IsFalse(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/planb.html"), userAgent));
 			Assert.IsFalse(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/planb.html?foo=bar"), userAgent));
 		}
+
+		[TestMethod]
+		public void OnlyWildcard()
+		{
+			var robotsFile = GetRobotsFile("Comprehensive-Example.txt");
+			var userAgent = "OnlyWildcard";
+
+			Assert.IsTrue(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/"), userAgent));
+			Assert.IsTrue(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/about.html"), userAgent));
+			Assert.IsFalse(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/plan.html?"), userAgent));
+			Assert.IsFalse(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/plan.html?foo="), userAgent));
+			Assert.IsFalse(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/plan.html"), userAgent));
+			Assert.IsTrue(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/planb.html"), userAgent));
+			Assert.IsTrue(robotsFile.IsAllowedAccess(new Uri("http://www.example.org/org/planb.html?foo=bar"), userAgent));
+		}
 	}
 }