def METHOD_NAME(self, arg):
    """Generate html report from .coverage and launch"""
    print('Generating HTML...')
    from coverage import coverage
    cov = coverage(auto_data=False, branch=True, data_suffix=None,
                   source=['vispy'])  # should match testing/_coverage.py
    cov.combine()
    cov.load()
    cov.html_report()
    print('Done, launching browser.')
    fname = op.join(os.getcwd(), 'htmlcov', 'index.html')
    if not op.isfile(fname):
        raise IOError('Generated file not found: %s' % fname)
    webbrowser.open_new_tab(fname)