def test_multiple_conflicting_constraints(self):
"""Test multiple conflicting constraint in nested constrain()'s."""
b = BooleanExpression('A xor B xor C')
with self.assertRaises(AlreadyConstrainedSymbolError) as cm:
with b.constrain(A=1, B=0, C=1):
with b.constrain(B=0, A=1):
pass
self.assertIn('Symbols "A", "B"', str(cm.exception))
def test_single_conflicting_nested_constraint(self):
"""Test single conflicting constraint in nested constrain()'s."""
b = BooleanExpression('A or B')
with self.assertRaises(AlreadyConstrainedSymbolError) as cm:
with b.constrain(A=1):
with b.constrain(A=1):
pass
self.assertIn('Symbol "A"', str(cm.exception))
def test_deep_conflicting_nested_constraint(self):
"""Test a conflict that occurs in a deeply nested context manager."""
b = BooleanExpression('A and B and C and D and E')
with self.assertRaises(AlreadyConstrainedSymbolError) as cm:
with b.constrain(A=0):
with b.constrain(B=0):
with b.constrain(C=0):
with b.constrain(D=0):
with b.constrain(E=0):
with b.constrain(B=0, D=0, E=1):
pass
self.assertIn('Symbols "B", "D", "E"', str(cm.exception))
def test_invalid_boolean_value(self):
"""Test passing an invalid Boolean value for a constraint."""
b = BooleanExpression('A or B')
with self.assertRaises(InvalidBooleanValueError):
with b.constrain(B='a string'):
pass
def test_invalid_symbol(self):
"""Test passing a symbol not present in the expression."""
b = BooleanExpression('A or B')
with self.assertRaises(ExtraSymbolError):
with b.constrain(C=0):
pass
def test_empty_constraints(self):
"""Test passing no constraints through kwargs."""
b = BooleanExpression('A or B')
with self.assertRaises(InvalidArgumentValueError):
with b.constrain():
pass