def test_forward_chaining():
def condition1(subject):
return subject['animal'] == 'dog'
def condition2(subject):
return subject['legsQuantity'] == '4'
def consequence1(subject):
subject['legsQuantity'] = '4'
def consequence2(subject):
subject['locomotion'] = 'quadruped'
rule1 = Rule('all dogs have 4 legs', condition1, consequence1, {'animal': 'dog'}, ('animal',))
rule2 = Rule('Anything with 4 legs is a quadruped', condition2, consequence2, {'legsQuantity': '4'},
('legsQuantity',))
rs = RuleSet()
rs.add_rule(rule1)
rs.add_rule(rule2)
kb = KnowledgeBase()
kb.add_knowledge({'animal': 'dog'})
ie = ForwardChainingInferenceEngine(kb, rs)
ie.run_engine()
assert ie.knowledge_base.knowledge == {'animal': 'dog', 'legsQuantity': '4', 'locomotion': 'quadruped'}
def test_backward_chaining_missing_rule_when_false():
def condition1(subject):
return subject['animal'] == 'dog'
def condition2(subject):
return subject['legsQuantity'] == '4'
def consequence1(subject):
subject['legsQuantity'] = '4'
def consequence2(subject):
subject['locomotion'] = 'quadruped'
rule2 = Rule('Anything with 4 legs is a quadruped', condition2, consequence2, {'legsQuantity': '4'},
('legsQuantity',))
rs = RuleSet()
rs.add_rule(rule2)
kb = KnowledgeBase()
kb.add_knowledge({'animal': 'dog'})
ie = BackwardChainingInferenceEngine(kb, rs)
ie.set_hypothesis({'locomotion': 'quadruped'})
assert ie.run_engine() is False
def test_knowledge_base_add_rule_twice_should_raise_an_exception():
def condition(subject):
return subject['fruit'] == 'strawberry'
def consequence(subject):
subject['color'] = 'red'
rule = Rule('all strawberries are red', condition, consequence, {'fruit': 'strawberry'}, ('fruit',))
rs = RuleSet()
rs.add_rule(rule)
with pytest.raises(RuleSet.DuplicatedRuleException):
rs.add_rule(rule)
def test_knowledge_base_add_rule_adds_new_rule():
def condition(subject):
return subject['fruit'] == 'strawberry'
def consequence(subject):
subject['color'] = 'red'
rule = Rule('all strawberries are red', condition, consequence, {'fruit': 'strawberry'}, ('fruit',))
rs = RuleSet()
rs.add_rule(rule)
assert len(rs.rules) == 1
assert len(rs.rules_tree) == 1
def test_knowledge_base_add_rule_and_then_retrieve_it_returns_the_correct_one():
def condition(subject):
return subject['fruit'] == 'strawberry'
def consequence(subject):
subject['color'] = 'red'
rule = Rule('all strawberries are red', condition, consequence, {'fruit': 'strawberry'}, ('fruit',))
rs = RuleSet()
rs.add_rule(rule)
assert rs.rules.get(rule.name) == rule
assert rs.rules_tree.get(rule.fields)[0] == rule
def test_knowledge_base_add_two_rules_with_same_fields():
def condition1(subject):
return subject['fruit'] == 'strawberry'
def condition2(subject):
return subject['fruit'] == 'kiwi'
def consequence1(subject):
subject['color'] = 'red'
def consequence2(subject):
subject['color'] = 'brown'
rule1 = Rule('all strawberries are red', condition1, consequence1, {'fruit': 'strawberry'}, ('fruit',))
rule2 = Rule('all kiwis are brown', condition2, consequence2, {'fruit': 'kiwi'}, ('fruit',))
rs = RuleSet()
rs.add_rule(rule1)
rs.add_rule(rule2)
assert len(rs.rules) == 2
assert len(rs.rules_tree) == 1
assert len(rs.rules_tree.get(('fruit',))) == 2