Support solution path which is simply a filename.

src/Giles.Core/Watchers/SourceWatcher.cs

@@ -62,16 +62,25 @@ void buildTimer_Elapsed(object sender, ElapsedEventArgs e)
 
         public void Watch(string solutionPath, string filter)
         {
-            var solutionFolder = fileSystem.GetDirectoryName(solutionPath);
-            var fileSystemWatcher = fileWatcherFactory.Build(solutionFolder, filter, ChangeAction, null,
-                                                                           ErrorAction);
+            string solutionFolder = GetSolutionFolder(solutionPath);
+            var fileSystemWatcher = fileWatcherFactory.Build(solutionFolder,
+                filter, ChangeAction, null, ErrorAction);
             fileSystemWatcher.EnableRaisingEvents = true;
             fileSystemWatcher.NotifyFilter = NotifyFilters.LastWrite;
             fileSystemWatcher.IncludeSubdirectories = true;
 
             FileWatchers.Add(fileSystemWatcher);
         }
 
+        private string GetSolutionFolder(string solutionPath)
+        {
+            var solutionFolder = fileSystem.GetDirectoryName(solutionPath);
+            // handle relative solution path that was only a filename
+            if (solutionFolder == string.Empty)
+                solutionFolder = "." + Path.DirectorySeparatorChar;
+            return solutionFolder;
+        }
+
         public void ErrorAction(object sender, ErrorEventArgs e)
         {
             throw new NotImplementedException();

src/Giles.Specs/Core/Watchers/SourceWatcherSpecs.cs

@@ -67,6 +67,20 @@ public class when_starting_to_watch_files : with_a_source_watcher
             fileSystem.Received().GetDirectoryName(path);
     }
 
+    public class when_the_solution_path_is_a_relative_filename : with_a_source_watcher
+    {
+        Establish context = () => {
+            path = "mySolution.sln";
+            fileSystem.GetDirectoryName(path).ReturnsForAnyArgs(info => Path.GetDirectoryName(info.Arg<string>()));
+        };
+
+        Because of = () =>
+            watcher.Watch(path, filter);
+
+        It watch_files_in_the_current_directory = () =>
+            fileWatcherFactory.Received().Build(@".\", filter, Arg.Any<FileSystemEventHandler>(), Arg.Any<FileSystemEventHandler>(), Arg.Any<ErrorEventHandler>());
+    }
+
 
     public class when_a_file_has_changed : with_a_source_watcher
     {
@@ -98,4 +112,4 @@ public class when_disposing : with_a_source_watcher
         It should_call_dispose_on_each_file_watcher = () =>
             watcher.FileWatchers.All(x => x == null);
     }
-}
+}