def test_oldStartSymbolShouldStaySame(self):
g = Grammar(nonterminals=[A], start_symbol=A)
self.assertIsNotNone(g.start)
with self.assertRaises(NonterminalDoesNotExistsException):
g.start = B
self.assertIsNotNone(g.start)
self.assertIs(g.start, A)
def test_shouldNotSetStartSymbol(self):
g = Grammar(nonterminals=[A, B])
self.assertIsNone(g.start)
with self.assertRaises(NotNonterminalException):
g.start = 'asdf'
self.assertIsNone(g.start)
self.assertFalse(g.start == 'asdf')
def test_oldStartSymbolShouldStaySame(self):
g = Grammar(nonterminals=[A, B], start_symbol=A)
self.assertIsNotNone(g.start)
self.assertIs(g.start, A)
with self.assertRaises(NotNonterminalException):
g.start = 'asdf'
self.assertIsNotNone(g.start)
self.assertIs(g.start, A)
def test_shouldNotSetStartSymbol(self):
g = Grammar(nonterminals=[A])
self.assertIsNone(g.start)
with self.assertRaises(NonterminalDoesNotExistsException):
g.start = B
self.assertIsNone(g.start)
