Check response invalid content type

openapi_core/responses.py

@@ -3,6 +3,7 @@ from functools import lru_cache
 
 from six import iteritems
 
+from openapi_core.exceptions import InvalidContentType
 from openapi_core.media_types import MediaTypeGenerator
 from openapi_core.parameters import ParametersGenerator
 
@@ -18,6 +19,13 @@ class Response(object):
         self.content = content and dict(content) or {}
         self.links = links and dict(links) or {}
 
+    def __getitem__(self, mimetype):
+        try:
+            return self.content[mimetype]
+        except KeyError:
+            raise InvalidContentType(
+                "Invalid mime type `{0}`".format(mimetype))
+
 
 class ResponsesGenerator(object):
 

openapi_core/validators.py

@@ -167,7 +167,7 @@ class ResponseValidator(object):
 
         if operation_response.content:
             try:
-                media_type = operation_response.content[response.mimetype]
+                media_type = operation_response[response.mimetype]
             except OpenAPIMappingError as exc:
                 errors.append(exc)
             else:

tests/integration/test_validators.py

@@ -206,6 +206,17 @@ class TestResponseValidator(object):
         assert result.body is None
         assert result.headers == {}
 
+    def test_invalid_content_type(self, validator):
+        request = MockRequest(self.host_url, 'get', '/v1/pets')
+        response = MockResponse('Not Found', mimetype='text/csv')
+
+        result = validator.validate(request, response)
+
+        assert len(result.errors) == 1
+        assert type(result.errors[0]) == InvalidContentType
+        assert result.body is None
+        assert result.headers == {}
+
     def test_missing_body(self, validator):
         request = MockRequest(self.host_url, 'get', '/v1/pets')
         response = MockResponse(None)