A patch that updates ScrubPath to handle when the "text" parameter is null.

Examples.txt

// I expected scrub path to handle null input.  There is no reason to let the
// NullReferenceException to propogate, since Verify can handle nulls.

// This test will pass or fail based on the contents of approved.txt
[TestMethod]
public void MyTestMethod()
{
    string file = null;
    ApprovalTests.Approvals.Verify(file);
}

// This test always fails with a NullReferenceException.
[TestMethod]
public void MyTestMethod1()
{
    var dir = PathUtilities.GetDirectoryForCaller();
    string file = null;
    ApprovalTests.Approvals.Verify(file.ScrubPath(dir));
}

// This test will pass or fail based on the contents of approved.txt
[TestMethod]
public void MyTestMethod3()
{
    var dir = PathUtilities.GetDirectoryForCaller();
    string file = string.Empty;
    ApprovalTests.Approvals.Verify(file.ScrubPath(dir));
}

ScrubPath.patch

Index: ApprovalUtilities.Tests/Utilities/PathUtilitiesTest.cs
===================================================================
--- ApprovalUtilities.Tests/Utilities/PathUtilitiesTest.cs	(revision 411)
+++ ApprovalUtilities.Tests/Utilities/PathUtilitiesTest.cs	(working copy)
@@ -17,5 +17,13 @@
             var file = dir + "PathUtilitiesTest.cs";
             Assert.AreEqual(@"...\PathUtilitiesTest.cs", PathUtilities.ScrubPath(file, dir));
         }
+
+        [TestMethod]
+        public void ReturnNullForNullTest()
+        {
+            var dir = PathUtilities.GetDirectoryForCaller();
+            string file = null;
+            Assert.IsNull(file.ScrubPath(dir));
+        }
     }
 }
Index: ApprovalUtilities/Utilities/PathUtilities.cs
===================================================================
--- ApprovalUtilities/Utilities/PathUtilities.cs	(revision 411)
+++ ApprovalUtilities/Utilities/PathUtilities.cs	(working copy)
@@ -23,6 +23,11 @@
 
         public static string ScrubPath(this string text, string path)
         {
+            if (text == null)
+            {
+                return null;
+            }
+
             return text.Replace(path, @"...\");
         }
     }