def test_spaced_words(self):
     self.assertEqual(first_word(" a word "), "a", "Case 2")
 def test_int(self):
     self.assertEqual(first_word(1), "invalid value", "Case 8")
 def test_two_words(self):
     self.assertEqual(first_word("Hello world"), "Hello", "Case 1")
 def test_empty_text(self):
     self.assertEqual(first_word(""), "invalid value", "Case 7")
 def test_one_word(self):
     self.assertEqual(first_word("hi"), "hi", "Case 6")
 def test_dot(self):
     self.assertEqual(first_word("Hello.World"), "Hello", "Case 5")
 def test_comma(self):
     self.assertEqual(first_word("greetings, friends"), "greetings", "Case 4")
 def test_apostrophe(self):
     self.assertEqual(first_word("don't touch it"), "don't", "Case 3")