jj: test if path is directory

Filesystem/File.vb

@@ -39,13 +39,16 @@ Public Class File
     ''' <param name="ContinueOnError">Should the function continue with deleting when a file could not be deleted?</param>
     ''' <returns>True if all files were deleted or if no files were deleted, otherwise false</returns>
     Public Function RemoveFiles(Path As String, FileKeepTime As Integer, FileBaseName As String, Optional FileExtension As String = "log", Optional ContinueOnError As Boolean = True) As Boolean
+        If Not TestPathIsDirectory(Path) Then
+            Throw New ArgumentException($"Path {Path} is not a directory!")
+        End If
+
         If Not Directory.Exists(Path) Then
-            _logger.Warn("Directory {0} does not exist")
-            Return False
+            Throw New DirectoryNotFoundException($"Path {Path} does not exist!")
         End If
 
         If FileKeepTime < 0 Or FileKeepTime > 1000 Then
-            Throw New ArgumentOutOfRangeException("FileKeepTime must be an integer between 0 and 1000")
+            Throw New ArgumentOutOfRangeException("FileKeepTime must be an integer between 0 and 1000!")
         End If
 
         Dim oUnableToDeleteCounter = 0
@@ -85,4 +88,10 @@ Public Class File
 
         Return True
     End Function
+
+    Private Function TestPathIsDirectory(Path As String) As Boolean
+        Dim oIsDirectory As Boolean = (System.IO.File.GetAttributes(Path) And FileAttributes.Directory) = FileAttributes.Directory
+        Return oIsDirectory
+    End Function
+
 End Class