def pytest_funcarg__index_html_file(request):
    """
    Return the path of the ``index.html`` created by building.

    This file contains the ``content`` rendered as HTML.  The ``app`` is build
    by this funcarg to generate the ``index.html`` file.
    """
    app = request.getfuncargvalue('app')
    app.build()
    outdir = request.getfuncargvalue('outdir')
    return outdir.join('index.html')