code: def test_families(self):
      self.assertRaises(RuntimeError, font.families)
      root = tkinter.Tk()
      families = font.families()
      self.assertIsInstance(families, tuple)
      self.assertTrue(families)
      for family in families:
          self.assertIsInstance(family, str)
          self.assertTrue(family)
      root.destroy()
      tkinter.NoDefaultRoot()
      self.assertRaises(RuntimeError, font.families)
  
imports: import unittest
  import tkinter
  from tkinter import font
  from test.support import requires, gc_collect, ALWAYS_EQ
  from test.test_tkinter.support import AbstractTkTest, AbstractDefaultRootTest
label_desc: Use image node_id 1 for calling the DefaultRootTest obj's underlying member method code with example usage: obj.test_families() without return types