Resharper Live macro mask that changes the variable name on exit

Question

I would like to create a Resharper Live Template that changes all spaces to emphasize my “actual” Live $ testname $ template variable:

<Fact()> _
Public Sub $testnames$()
    ' Arrange
    $END$

    ' Act

    ' Assert

End Sub

I have it:

    [Macro("applyRegex", ShortDescription = "Run on {#0:variable}", LongDescription = "")]
    class ApplyRegexMacro : IMacro
    {
        public string EvaluateQuickResult(IHotspotContext context, IList<string> arguments)
        {
            return Regex.Replace(arguments[0], " ", "_", RegexOptions.IgnoreCase);
        }

        public HotspotItems GetLookupItems(IHotspotContext context, IList<string> arguments)
        {
            return null;
        }

        public string GetPlaceholder()
        {
            return "placeholder";
        }

        public bool HandleExpansion(IHotspotContext context, IList<string> arguments)
        {
            return false;
        }

        public ParameterInfo[] Parameters
        {
            get
            {
                return new[] { new ParameterInfo(ParameterType.String), new ParameterInfo(ParameterType.String), new ParameterInfo(ParameterType.VariableReference) };           
            }
        }
    }

But this only works when you click a tab. I want the macro to run after I exit $ testname $.

I want to be able to simply write a test name in one line of text with spaces, and then the macro will turn all spaces into underscores.

Is it possible?