'Test the _write_font() method. Font name.'

def test_write_font_8(self):

    properties = {'font_name': 'Arial'}
    xf_format = Format(properties)
    self.styles._write_font(xf_format)
    exp = '<font><sz    val="11"/><color    theme="1"/><name    val="Arial"/><family    val="2"/></font>'
    got = self.fh.getvalue()
    self.assertEqual(got, exp)
