Fix the checking of solutions containing MiniZinc defined enums

Author: Dekker1

CHANGELOG.rst

@@ -22,13 +22,17 @@ Changed
 ^^^^^^^
 - The MiniZinc Python repository moved from GitLab to GitHub, replacing GitLab
   CI for GitHub Actions for the continuous testing.
+- Values of an enumerated type defined in MiniZinc will now appear in solutions
+  as a member of a singular anonymous ``enum.Enum`` class.
 
 Fixed
 ^^^^^
 - Handle the cancellation of asynchronous solving and correctly dispose of the
   process
 - Correct the JSON representation of sets of with ``IntEnum`` members. (Lists
   are still not correctly represented).
+- ``check_solution`` will now correctly handle solution values of an enumerated
+  type defined in MiniZinc.
 
 0.4.0_ - 2020-10-06
 ------------

src/minizinc/json.py

@@ -24,6 +24,16 @@ def __init__(self, enum_map=None, *args, **kwargs):
             self.enum_map = enum_map
         JSONDecoder.__init__(self, object_hook=self.object_hook, *args, **kwargs)
 
+    def _lookup_enum(self, name: str):
+        if name in self.enum_map:
+            return self.enum_map[name]
+        else:
+            # TODO: mypy seems to believe name the elements should be literals,
+            # but I cannot find this anywhere in the documentation
+            anon_enum = Enum("AnonymousEnum", name)  # type: ignore
+            self.enum_map[name] = anon_enum(1)
+            return anon_enum(1)
+
     def object_hook(self, obj):
         if len(obj) == 1 and "set" in obj:
             if len(obj["set"]) == 1 and isinstance(obj["set"][0], list):
@@ -36,11 +46,11 @@ def object_hook(self, obj):
                     assert len(item) == 2
                     li.extend([i for i in range(item[0], item[1] + 1)])
                 elif len(obj) == 1 and "e" in obj:
-                    li.append(self.enum_map.get(obj["e"], obj["e"]))
+                    li.append(self._lookup_enum(obj["e"]))
                 else:
                     li.append(item)
             return set(li)
         elif len(obj) == 1 and "e" in obj:
-            return self.enum_map.get(obj["e"], obj["e"])
+            return self._lookup_enum(obj["e"])
         else:
             return obj

tests/test_helpers.py

@@ -42,3 +42,8 @@ def test_dict(self):
         assert check_solution(
             self.instance, {"x": [5, 6]}, Status.SATISFIED, self.other_solver
         )
+
+    def test_enum(self):
+        self.instance.add_string("""enum Foo = {A, B};var Foo: f;""")
+        result = self.instance.solve()
+        assert check_result(self.instance, result, self.other_solver)

tests/test_types.py

@@ -17,15 +17,15 @@ class TestEnum(InstanceTestCase):
     def test_value(self):
         self.instance.add_string("constraint d == Mo;")
         result = self.instance.solve()
-        assert isinstance(result["d"], str)
-        assert result["d"] == "Mo"
+        assert isinstance(result["d"], enum.Enum)
+        assert result["d"].name == "Mo"
 
     def test_cmp_in_instance(self):
         self.instance.add_string("var DAY: d2;")
         self.instance.add_string("constraint d < d2;")
         result = self.instance.solve()
-        assert isinstance(result["d"], str)
-        assert isinstance(result["d2"], str)
+        assert isinstance(result["d"], enum.Enum)
+        assert isinstance(result["d2"], enum.Enum)
         # TODO: assert result["d"] < result["d2"]
 
     def test_cmp_between_instances(self):
@@ -36,9 +36,9 @@ def test_cmp_between_instances(self):
         inst = Instance(self.solver)
         inst.add_string(self.code + append)
         result2 = inst.solve()
-        assert isinstance(result["d"], str)
-        assert isinstance(result2["d"], str)
-        assert result["d"] == result2["d"]
+        assert isinstance(result["d"], enum.Enum)
+        assert isinstance(result2["d"], enum.Enum)
+        assert result["d"].name == result2["d"].name
 
         inst = Instance(self.solver)
         inst.add_string(
@@ -49,8 +49,7 @@ def test_cmp_between_instances(self):
             + append
         )
         result2 = inst.solve()
-        # TODO: assert type(result["d"]) != type(result2["d"])
-        # TODO: assert result["d"] == result2["d"]
+        assert result["d"].name == result2["d"].name
 
     def test_assign(self):
         self.instance = Instance(self.solver)