Add the ability to specify AnnotateImageRequest items in single-feature methods.

vision/google/cloud/vision/decorators.py

@@ -85,6 +85,8 @@ def _create_single_feature_method(feature, enum):
         image (:class:`~.{module}.types.Image`): The image to analyze.
         options (:class:`google.gax.CallOptions`): Overrides the
             default settings for this call, e.g, timeout, retries, etc.
+        kwargs (dict): Additional properties to be set on the
+            :class:`~.{module}.types.AnnotateImageRequest`.
 
     Returns:
         :class:`~.{module}.types.AnnotateImageResponse`: The API response.
@@ -94,16 +96,17 @@ def _create_single_feature_method(feature, enum):
     feature_value = {'type': enum.__dict__[feature]}
 
     # Define the function to be returned.
-    def inner(self, image, options=None):
+    def inner(self, image, options=None, **kwargs):
         """Return a single feature annotation for the given image.
 
         Intended for use with functools.partial, to create the particular
         single-feature methods.
         """
-        request = {
-            'image': image,
-            'features': [feature_value],
-        }
+        request = dict(
+            image=image,
+            features=[feature_value],
+            **kwargs
+        )
         return self.annotate_image(request, options=options)
 
     # Set the appropriate function metadata.

vision/tests/unit/test_decorators.py

@@ -55,15 +55,21 @@ class SingleFeatureMethodTests(unittest.TestCase):
     def test_runs_generic_single_image(self, ai):
         ai.return_value = vision.types.AnnotateImageResponse()
 
+        # Prove that other aspects of the AnnotateImageRequest, such as the
+        # image context, will be preserved.
+        SENTINEL = object()
+
         # Make a face detection request.
         client = vision.ImageAnnotatorClient(
             credentials=mock.Mock(spec=Credentials),
         )
         image = {'source': {'image_uri': 'gs://my-test-bucket/image.jpg'}}
-        response = client.face_detection(image)
+        response = client.face_detection(image, image_context=SENTINEL)
+        assert isinstance(response, vision.types.AnnotateImageResponse)
 
         # Assert that the single-image method was called as expected.
         ai.assert_called_once_with({
             'features': [{'type': vision.enums.Feature.Type.FACE_DETECTION}],
             'image': image,
+            'image_context': SENTINEL,
         }, options=None)