I have actually got it to work using PowerShell and the Navigate
method in the VS core automation wrapper, EnvDTE.
I replaced the last call
command with the following:
powershell
-ExecutionPolicy Unrestricted
-Command "& { $dte = [System.Runtime.InteropServices.Marshal]::
GetActiveObject(\"VisualStudio.DTE.11.0\");
$dte.ItemOperations.Navigate(
\"$(SolutionDir)TestResults\Coverage\index.htm\"); }"
And that opens the report in a new browser tab inside the VS project.