1

  Sub associerExtension()

        Dim extension As String = ".test1"
        Dim nomSansPoint As String = extension.Substring(1, extension.Length - 1) 'on aura uniquement test1
        Dim cheminFinalProgramme As String = "<VOTRE CHEMIN ICI>"

        My.Computer.Registry.ClassesRoot.CreateSubKey(extension).SetValue("", nomSansPoint, Microsoft.Win32.RegistryValueKind.String)
        My.Computer.Registry.ClassesRoot.CreateSubKey(nomSansPoint & "\shell\open\command").SetValue _
            ("", cheminFinalProgramme  & " ""%l"" ", Microsoft.Win32.RegistryValueKind.String)

    End Sub