Fixed flaky metamorphic relations tests.

Re-defined equality for the metamorphic relation class and this ensures the order of the adjustment set doesn't matter.

Author: AndrewC19

causal_testing/specification/metamorphic_relation.py

@@ -107,6 +107,13 @@ def test_oracle(self, test_results):
         This method must raise an assertion, not return a bool."""
         ...
 
+    def __eq__(self, other):
+        same_type = self.__class__ == other.__class__
+        same_treatment = self.treatment_var == other.treatment_var
+        same_output = self.output_var == other.output_var
+        same_adjustment_set = set(self.adjustment_vars) == set(other.adjustment_vars)
+        return same_type and same_treatment and same_output and same_adjustment_set
+
 
 class ShouldCause(MetamorphicRelation):
     """Class representing a should cause metamorphic relation."""

tests/specification_tests/test_metamorphic_relations.py

@@ -164,3 +164,45 @@ def test_all_metamorphic_relations_implied_by_dag(self):
 
         self.assertEqual(extra_snc_relations, [])
         self.assertEqual(missing_snc_relations, [])
+
+    def test_equivalent_metamorphic_relations(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", ["A", "B", "C"], dag)
+        sc_mr_b = ShouldCause("X", "Y", ["A", "B", "C"], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, True)
+
+    def test_equivalent_metamorphic_relations_empty_adjustment_set(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", [], dag)
+        sc_mr_b = ShouldCause("X", "Y", [], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, True)
+
+    def test_equivalent_metamorphic_relations_different_order_adjustment_set(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", ["A", "B", "C"], dag)
+        sc_mr_b = ShouldCause("X", "Y", ["C", "A", "B"], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, True)
+
+    def test_different_metamorphic_relations_empty_adjustment_set_different_outcome(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Z", [], dag)
+        sc_mr_b = ShouldCause("X", "Y", [], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, False)
+
+    def test_different_metamorphic_relations_empty_adjustment_set_different_treatment(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", [], dag)
+        sc_mr_b = ShouldCause("Z", "Y", [], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, False)
+
+    def test_different_metamorphic_relations_empty_adjustment_set_adjustment_set(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", ["A"], dag)
+        sc_mr_b = ShouldCause("X", "Y", [], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, False)
+
+    def test_different_metamorphic_relations_different_type(self):
+        dag = CausalDAG(self.dag_dot_path)
+        sc_mr_a = ShouldCause("X", "Y", [], dag)
+        sc_mr_b = ShouldNotCause("X", "Y", [], dag)
+        self.assertEqual(sc_mr_a == sc_mr_b, False)