Rule.add_factor returns None if contradiction is caused

authorityspoke/holdings.py

@@ -224,7 +224,7 @@ def add_holding(self, other: Holding) -> Optional[Holding]:
                     return added
         return None
 
-    def __add__(self, other: Factor) -> Optional[Union[Rule, Holding]]:
+    def __add__(self, other: Comparable) -> Optional[Union[Rule, Holding]]:
         """
         Create new Holding combining self and other into a single step, if possible.
 

authorityspoke/procedures.py

@@ -293,7 +293,7 @@ def generic_terms_by_str(self) -> Dict[str, Term]:
         }
         return generic_dict
 
-    def add_factor(self, incoming: Factor) -> Procedure:
+    def add_factor(self, incoming: Factor) -> Optional[Procedure]:
         """
         Add an input :class:`.Factor`.
 
@@ -303,7 +303,9 @@ def add_factor(self, incoming: Factor) -> Procedure:
         :returns:
             a new version of ``self`` with the specified change
         """
-        new_factors = list(self.inputs) + [incoming]
+        new_factors = self.inputs + incoming
+        if new_factors is None:
+            return None
         result = deepcopy(self)
         result.set_inputs(new_factors)
         return result

authorityspoke/rules.py

@@ -273,7 +273,7 @@ def add_enactment_despite(self, incoming: Enactment) -> Rule:
         result.set_enactments_despite(new_enactments)
         return result
 
-    def add_factor(self, incoming: Factor) -> Rule:
+    def add_factor(self, incoming: Factor) -> Optional[Rule]:
         """
         Make new version of ``self`` with an added input, output, or despite :class:`.Factor`.
 
@@ -287,6 +287,8 @@ def add_factor(self, incoming: Factor) -> Rule:
             a new version of ``self`` with the specified change
         """
         new_procedure = self.procedure.add_factor(incoming)
+        if new_procedure is None:
+            return None
         result = deepcopy(self)
         result.procedure = new_procedure
         return result

requirements.txt

@@ -2,7 +2,7 @@ anchorpoint>=0.4.4
 apispec[validation]~=4.3.0
 marshmallow>=3.10
 legislice>=0.5.0
-git+git://github.com/mscarey/nettlesome.git@c1c680b542ce74edc39747d32ea024ff24363ae6#egg=nettlesome
+git+git://github.com/mscarey/nettlesome.git@beb4d3f6eb2c731d47afcdcec4d422745400a3d0#egg=nettlesome
 pint>=0.15
 python-dotenv
 python-slugify

tests/test_holdings.py

@@ -39,6 +39,9 @@ def test_string_indentation(self, make_opinion_with_holding):
         lotus = make_opinion_with_holding["lotus_majority"]
         assert "    OF:\n" in str(lotus.holdings[2])
 
+    def test_repr(self, make_holding):
+        assert "rule=Rule(" in repr(make_holding["h1"])
+
     def test_line_break_in_fact_within_holding(self, make_opinion_with_holding):
         """
         Test that holding uses the Fact string method with line breaks.
@@ -600,6 +603,11 @@ def test_universal_holding_that_cannot_be_added(self, make_rule):
         right = make_rule["h3_ALL"]
         assert left + right is None
 
+    def test_add_contradictory_factor(self, make_holding):
+        holding = make_holding["h1"]
+        factor = holding.inputs[0].negated()
+        assert holding + factor is None
+
 
 class TestUnion:
     def test_union_neither_universal(self, make_opinion_with_holding):

tests/test_notebooks.py

@@ -101,7 +101,7 @@ def test_opinion_explain_contradiction(self, make_opinion_with_holding):
         assert "<the Lotus menu command hierarchy> is like <the Java API>" in str(
             explanation
         )
-        assert 'Entity(name="the Java API"' in repr(explanation)
+        assert "Entity(name='the Java API'" in repr(explanation)
 
     def test_decision_explain_contradiction(self, make_decision_with_holding):
         oracle = make_decision_with_holding["oracle"]

tests/test_procedures.py

@@ -69,9 +69,8 @@ def test_type_of_terms(self, make_procedure):
         assert isinstance(make_procedure["c3"].terms, TermSequence)
 
     def test_repr(self, make_procedure):
-        assert 'to_effect=Fact(Predicate(template="$person committed a crime"' in repr(
-            make_procedure["c3"]
-        )
+        rep = repr(make_procedure["c3"])
+        assert "to_effect=Fact(predicate=Predicate(template='$person committed" in rep
 
     def test_entities_of_inputs_for_identical_procedure(
         self, watt_factor, make_procedure, watt_mentioned