From 618605922f68073936ece934c92f1586c5a45e4d Mon Sep 17 00:00:00 2001
From: Danny Hermes <daniel.j.hermes@gmail.com>
Date: Thu, 12 Mar 2015 14:58:37 -0700
Subject: [PATCH] Using 'fields' in Bucket.exists().

This decouples Bucket.exists() from Connection.get_bucket().

Relevant to #632.
---
 gcloud/storage/bucket.py      |  6 +++++-
 gcloud/storage/test_bucket.py | 38 +++++++++++++++++++++++++----------
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/gcloud/storage/bucket.py b/gcloud/storage/bucket.py
index 210edbbbbd77..cba3b43ced62 100644
--- a/gcloud/storage/bucket.py
+++ b/gcloud/storage/bucket.py
@@ -132,7 +132,11 @@ def exists(self):
         :returns: True if the bucket exists in Cloud Storage.
         """
         try:
-            self.connection.get_bucket(self.name)
+            # We only need the status code (200 or not) so we seek to
+            # minimize the returned payload.
+            query_params = {'fields': 'name'}
+            self.connection.api_request(method='GET', path=self.path,
+                                        query_params=query_params)
             return True
         except NotFound:
             return False
diff --git a/gcloud/storage/test_bucket.py b/gcloud/storage/test_bucket.py
index fbe6b3c994fc..4bef81ad5f4d 100644
--- a/gcloud/storage/test_bucket.py
+++ b/gcloud/storage/test_bucket.py
@@ -159,14 +159,22 @@ class _FakeConnection(object):
             _called_with = []
 
             @classmethod
-            def get_bucket(cls, bucket_name):
-                cls._called_with.append(bucket_name)
-                raise NotFound(bucket_name)
+            def api_request(cls, *args, **kwargs):
+                cls._called_with.append((args, kwargs))
+                raise NotFound(args)
 
-        NAME = 'name'
-        bucket = self._makeOne(connection=_FakeConnection, name=NAME)
+        BUCKET_NAME = 'bucket-name'
+        bucket = self._makeOne(connection=_FakeConnection, name=BUCKET_NAME)
         self.assertFalse(bucket.exists())
-        self.assertEqual(_FakeConnection._called_with, [NAME])
+        expected_called_kwargs = {
+            'method': 'GET',
+            'path': bucket.path,
+            'query_params': {
+                'fields': 'name',
+            },
+        }
+        expected_cw = [((), expected_called_kwargs)]
+        self.assertEqual(_FakeConnection._called_with, expected_cw)
 
     def test_exists_hit(self):
         class _FakeConnection(object):
@@ -174,15 +182,23 @@ class _FakeConnection(object):
             _called_with = []
 
             @classmethod
-            def get_bucket(cls, bucket_name):
-                cls._called_with.append(bucket_name)
+            def api_request(cls, *args, **kwargs):
+                cls._called_with.append((args, kwargs))
                 # exists() does not use the return value
                 return object()
 
-        NAME = 'name'
-        bucket = self._makeOne(connection=_FakeConnection, name=NAME)
+        BUCKET_NAME = 'bucket-name'
+        bucket = self._makeOne(connection=_FakeConnection, name=BUCKET_NAME)
         self.assertTrue(bucket.exists())
-        self.assertEqual(_FakeConnection._called_with, [NAME])
+        expected_called_kwargs = {
+            'method': 'GET',
+            'path': bucket.path,
+            'query_params': {
+                'fields': 'name',
+            },
+        }
+        expected_cw = [((), expected_called_kwargs)]
+        self.assertEqual(_FakeConnection._called_with, expected_cw)
 
     def test_acl_property(self):
         from gcloud.storage.acl import BucketACL