Do not reject enum values that are not listed in the proto file

According to the language guide [1]:

    During deserialization, unrecognized enum values will be preserved
    in the message, though how this is represented when the message is
    deserialized is language-dependent.

We can store any integer in the underlying field, because in Cython,
enum and int are the same.

Fixes appnexus#149.

pyrobuf/protobuf/templates/proto_pyx.tmpl

@@ -198,16 +198,7 @@ cdef class {{ message.full_name }}:
             {%- endif %}
         for val in value:
             {%- if field.type == 'enum' and field.enum_def != None %}
-                {%- for value, enum_field in field.enum_def.fields.items() %}
-                    {%- if loop.index == 1 %}
-            if val == {{ value }}:
-                    {%- else %}
-            elif val == {{ value }}:
-                    {%- endif %}
-                self._{{ field.name }}.append(_{{ enum_field.full_name }})
-                {% endfor %}
-            else:
-                raise ValueError("{} not a valid value for enum {{ field.enum_name }}".format(val))
+            self._{{ field.name }}.append(val)
             {%- elif field.type == 'string' and version_major == 2 %}
             if isinstance(val, unicode):
                 list.append(self._{{ field.name }}, val)
@@ -234,16 +225,7 @@ cdef class {{ message.full_name }}:
             {%- endif %}
         {%- else %}
             {%- if field.type == 'enum' and field.enum_def != None %}
-                {%- for value, enum_field in field.enum_def.fields.items() %}
-                    {%- if loop.index == 1 %}
-        if value == {{ value }}:
-                    {%- else %}
-        elif value == {{ value }}:
-                    {%- endif %}
-            self._{{ field.name }} = _{{ enum_field.full_name }}
-                {% endfor %}
-        else:
-            raise ValueError("{} not a valid value for enum {{ field.enum_name }}".format(value))
+        self._{{ field.name }} = value
             {%- elif field.type == 'string' and version_major == 2 %}
         if isinstance(value, unicode):
             self._{{ field.name }} = value

tests/proto/test_repeated_enum.proto

@@ -5,4 +5,5 @@ message TestRepeatedEnum {
         TEST_ENUM_FIELD_2 = 2;
     }
     repeated EnumField list_enum = 1;
+    optional EnumField single_enum = 2;
 }

tests/test_repeated_enum.py

@@ -17,12 +17,33 @@ def test_repeated_enum_serde(self):
         message1.list_enum.append(2)
         message1.list_enum.append(0)
         message1.list_enum.append(1)
+        # Must be able to handle arbitrary integers in enums:
+        message1.list_enum.append(42)
+        # ... but not arbitrary values:
+        with self.assertRaises(TypeError):
+            message1.list_enum.append('not an int')
 
         buf = message1.SerializeToString()
         message2.ParseFromString(buf)
 
         for i in range(len(message1.list_enum)):
             self.assertEqual(message1.list_enum[i], message2.list_enum[i])
 
+    def test_single_enum_serde(self):
+        message1 = TestRepeatedEnum()
+        message2 = TestRepeatedEnum()
+
+        message1.single_enum = 1
+        # Must be able to handle arbitrary integers in enums:
+        message1.single_enum = 42
+        # ... but not arbitrary values:
+        with self.assertRaises(TypeError):
+            message1.single_enum = 'not an int'
+
+        buf = message1.SerializeToString()
+        message2.ParseFromString(buf)
+
+        self.assertEqual(message1.single_enum, message2.single_enum)
+
 if __name__ == "__main__":
     unittest.main()