def test_shouldNotSetStartSymbol(self):
g = Grammar(nonterminals=[A, B])
self.assertFalse(g.start_isSet())
with self.assertRaises(NotNonterminalException):
g.start_set('asdf')
self.assertFalse(g.start_isSet())
self.assertFalse(g.start_is('asdf'))
def test_shouldNotSetStartSymbol(self):
g = Grammar(nonterminals=[A])
self.assertFalse(g.start_isSet())
with self.assertRaises(NonterminalDoesNotExistsException):
g.start_set(B)
self.assertFalse(g.start_isSet())
self.assertFalse(g.start_is(B))
def test_oldStartSymbolShouldStaySame(self):
g = Grammar(nonterminals=[A, B], start_symbol=A)
self.assertTrue(g.start_isSet())
with self.assertRaises(NotNonterminalException):
g.start_set('asdf')
self.assertTrue(g.start_isSet())
self.assertTrue(g.start_is(A))
self.assertEqual(g.start_get(), A)
