def test_pop(self):
buf = CharBuffer('a')
self.assertEqual('a', buf.pop())
self.assertRaises(EmptyBufferException, lambda: buf.pop())
def test_eof(self):
self.assertTrue(CharBuffer('').eof())
buf = CharBuffer('x')
self.assertFalse(buf.eof())
buf.pop()
self.assertTrue(buf.eof())
def test_peek(self):
buf = CharBuffer('a')
self.assertEqual('a', buf.peek())
buf.pop()
self.assertIsNone(buf.peek())