Fix handling of nonexistent MLTools in API

arkindex/project/serializer_fields.py

@@ -34,4 +34,7 @@ class MLToolField(serializers.CharField):
         return obj.slug
 
     def to_internal_value(self, data):
-        return MLTool.get(settings.ML_CLASSIFIERS_DIR, self.tool_type, data)
+        try:
+            return MLTool.get(settings.ML_CLASSIFIERS_DIR, self.tool_type, data)
+        except ValueError as e:
+            raise serializers.ValidationError(str(e))

arkindex/project/tests/test_mltoolfield.py

+from unittest.mock import patch, call, MagicMock
+from rest_framework.serializers import ValidationError
+from arkindex_common.ml_tool import MLTool, MLToolType
+from arkindex.project.tests import FixtureTestCase
+from arkindex.project.serializer_fields import MLToolField
+
+
+@patch('arkindex.project.serializer_fields.MLTool.get')
+class TestMLToolField(FixtureTestCase):
+
+    def test_to_representation(self, get_mock):
+        tool = MagicMock(spec=MLTool)
+        tool.slug = 'something'
+        field = MLToolField(MLToolType.Classifier)
+        self.assertEqual(field.to_representation(tool), 'something')
+
+    def test_to_internal_value(self, get_mock):
+        field = MLToolField(MLToolType.Classifier)
+        with self.settings(ML_CLASSIFIERS_DIR='/somewhere'):
+            self.assertEqual(
+                field.to_internal_value('something'),
+                get_mock.return_value,
+            )
+        self.assertEqual(get_mock.call_count, 1)
+        self.assertEqual(get_mock.call_args, call('/somewhere', MLToolType.Classifier, 'something'))
+
+    def test_not_type(self, get_mock):
+        with self.assertRaises(AssertionError):
+            MLToolField('Potato')
+
+    def test_missing(self, get_mock):
+        get_mock.side_effect = ValueError('Not found!')
+        field = MLToolField(MLToolType.Recognizer)
+        with self.assertRaisesMessage(ValidationError, 'Not found!'):
+            field.to_internal_value('something')