Partial behavior change and corresponding tests

Author: eliotwrobson

automata/fa/dfa.py

@@ -278,9 +278,8 @@ def to_partial(self, *, retain_names: bool = False, minify: bool = True) -> Self
         Self
             An equivalent partial DFA.
         """
-        if self.allow_partial:
-            return self.copy()
 
+        # Still want to try and remove dead states in the case of a partial DFA
         graph = self._get_digraph()
         live_states = get_reachable_nodes(graph, [self.initial_state])
         non_trap_states = get_reachable_nodes(graph, self.final_states, reversed=True)
@@ -338,8 +337,12 @@ def to_complete(self, trap_state: Optional[DFAStateT] = None) -> Self:
             An equivalent complete DFA.
 
         """
+        is_partial = any(
+            len(lookup) != len(self.input_symbols)
+            for lookup in self.transitions.values()
+        )
 
-        if not self.allow_partial:
+        if not is_partial:
             return self.copy()
 
         if trap_state is None:

tests/test_dfa.py

@@ -310,6 +310,21 @@ def test_equivalence_partials(self) -> None:
         self.assertEqual(self.partial_dfa, complete_dfa)
         self.assertEqual(self.partial_dfa, complete_dfa.to_partial(minify=False))
 
+        # Checking for equivalent number of states
+        self.assertEqual(complete_dfa.states, complete_dfa.to_complete().states)
+
+        # Make a fake partial DFA and check that the number of states is
+        # still reduced
+        test_dfa = DFA(
+            states=complete_dfa.states,
+            input_symbols=complete_dfa.input_symbols,
+            transitions=complete_dfa.transitions,
+            initial_state=complete_dfa.initial_state,
+            final_states=complete_dfa.final_states,
+            allow_partial=True,
+        )
+        self.assertTrue(test_dfa.to_partial(minify=False).states.issubset(complete_dfa.states))
+
     def test_equivalence_minify(self) -> None:
         """Should be equivalent after minify."""
         minimal_dfa = self.no_consecutive_11_dfa.minify()