def com_google_fonts_check_family_underline_thickness(ttFonts):
  """Fonts have consistent underline thickness?"""
  underTs = {}
  underlineThickness = None
  failed = False
  for ttfont in ttFonts:
    fontname = ttfont.reader.file.name
    # stylename = style(fontname)
    ut = ttfont['post'].underlineThickness
    underTs[fontname] = ut
    if underlineThickness is None:
      underlineThickness = ut
    if ut != underlineThickness:
      failed = True

  if failed:
    msg = ("Thickness of the underline is not"
           " the same accross this family. In order to fix this,"
           " please make sure that the underlineThickness value"
           " is the same in the 'post' table of all of this family"
           " font files.\n"
           "Detected underlineThickness values are:\n")
    for style in underTs.keys():
      msg += "\t{}: {}\n".format(style, underTs[style])
    yield FAIL, msg
  else:
    yield PASS, "Fonts have consistent underline thickness."
Fonts have consistent underline thickness?