Fitnesse - Getting the absolute path for a fitnesse url

I am busy learning fitnesse at the moment and have not been able to figure out how to work 开发者_JS百科out how to get an absolute path from a relative url. I want to be able to upload test files to the files directory on a fitnesse server and then read those files in my test fixture. e.g.

public void ReadTextFileContent(string fileName)
{
   Text = File.ReadAllText(fileName);
}

Note: The fileName would be the fully qualified path to the file. I want to be able to define this path in terms of the relative path to the fitnesse server so that in a multi user setup, users will not need to have their fitnesse server running on the same drive or path.

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The current directory (System.Environment.CurrentDirectory) will be the path in your FitNesee server -d parameter (e.g. java -jar \apps\fitnesse\fitnesse.jar -d path\to\my\fitnesse\wiki). From there you can look in FitNesseRoot\files.