bigquery: remove dataset.exists (#3996)

* bigquery: remove dataset.exists

Dataset won't be able to support this method when we remove its client.

Don't add client.dataset_exists; the user can use client.get_dataset and
catch NotFound.

* fix lint

* fix lint agian

* fix more lint

bigquery/google/cloud/bigquery/dataset.py

@@ -17,7 +17,6 @@
 
 from google.api.core import page_iterator
 from google.cloud._helpers import _datetime_from_microseconds
-from google.cloud.exceptions import NotFound
 from google.cloud.bigquery.table import Table
 from google.cloud.bigquery.table import TableReference
 
@@ -486,30 +485,6 @@ def _build_resource(self):
 
         return resource
 
-    def exists(self, client=None):
-        """API call:  test for the existence of the dataset via a GET request
-
-        See
-        https://cloud.google.com/bigquery/docs/reference/rest/v2/datasets/get
-
-        :type client: :class:`~google.cloud.bigquery.client.Client` or
-                      ``NoneType``
-        :param client: the client to use.  If not passed, falls back to the
-                       ``client`` stored on the current dataset.
-
-        :rtype: bool
-        :returns: Boolean indicating existence of the dataset.
-        """
-        client = self._require_client(client)
-
-        try:
-            client._connection.api_request(method='GET', path=self.path,
-                                           query_params={'fields': 'id'})
-        except NotFound:
-            return False
-        else:
-            return True
-
     def patch(self, client=None, **kw):
         """API call:  update individual dataset properties via a PATCH request.
 

bigquery/tests/system.py

@@ -25,10 +25,10 @@
 import six
 
 from google.cloud import bigquery
-from google.cloud.bigquery.dataset import Dataset
+from google.cloud.bigquery.dataset import Dataset, DatasetReference
 from google.cloud._helpers import UTC
 from google.cloud.bigquery import dbapi
-from google.cloud.exceptions import Forbidden
+from google.cloud.exceptions import Forbidden, NotFound
 
 from test_utils.retry import RetryErrors
 from test_utils.retry import RetryInstanceState
@@ -91,7 +91,6 @@ def setUp(self):
         self.to_delete = []
 
     def tearDown(self):
-        from google.cloud.bigquery.dataset import Dataset
         from google.cloud.storage import Bucket
         from google.cloud.exceptions import BadRequest
         from google.cloud.exceptions import Conflict
@@ -115,7 +114,7 @@ def test_create_dataset(self):
         dataset = retry_403(Config.CLIENT.create_dataset)(Dataset(DATASET_ID))
         self.to_delete.append(dataset)
 
-        self.assertTrue(dataset.exists())
+        self.assertTrue(_dataset_exists(dataset))
         self.assertEqual(dataset.dataset_id, DATASET_ID)
 
     def test_get_dataset(self):
@@ -138,7 +137,7 @@ def test_patch_dataset(self):
             Dataset(_make_dataset_id('patch_dataset')))
         self.to_delete.append(dataset)
 
-        self.assertTrue(dataset.exists())
+        self.assertTrue(_dataset_exists(dataset))
         self.assertIsNone(dataset.friendly_name)
         self.assertIsNone(dataset.description)
         dataset.patch(friendly_name='Friendly', description='Description')
@@ -150,7 +149,7 @@ def test_update_dataset(self):
             Dataset(_make_dataset_id('update_dataset')))
         self.to_delete.append(dataset)
 
-        self.assertTrue(dataset.exists())
+        self.assertTrue(_dataset_exists(dataset))
         after = [entry for entry in dataset.access_entries
                  if entry.entity_id != 'projectWriters']
         dataset.access_entries = after
@@ -1196,3 +1195,11 @@ def test_create_table_insert_fetch_nested_schema(self):
 
 def _job_done(instance):
     return instance.state.lower() == 'done'
+
+
+def _dataset_exists(ds):
+    try:
+        Config.CLIENT.get_dataset(DatasetReference(ds.project, ds.dataset_id))
+        return True
+    except NotFound:
+        return False

bigquery/tests/unit/test_dataset.py

@@ -386,37 +386,6 @@ def test__parse_access_entries_w_extra_keys(self):
         with self.assertRaises(ValueError):
             dataset._parse_access_entries(ACCESS)
 
-    def test_exists_miss_w_bound_client(self):
-        PATH = 'projects/%s/datasets/%s' % (self.PROJECT, self.DS_ID)
-        conn = _Connection()
-        client = _Client(project=self.PROJECT, connection=conn)
-        dataset = self._make_one(self.DS_ID, client=client)
-
-        self.assertFalse(dataset.exists())
-
-        self.assertEqual(len(conn._requested), 1)
-        req = conn._requested[0]
-        self.assertEqual(req['method'], 'GET')
-        self.assertEqual(req['path'], '/%s' % PATH)
-        self.assertEqual(req['query_params'], {'fields': 'id'})
-
-    def test_exists_hit_w_alternate_client(self):
-        PATH = 'projects/%s/datasets/%s' % (self.PROJECT, self.DS_ID)
-        conn1 = _Connection()
-        CLIENT1 = _Client(project=self.PROJECT, connection=conn1)
-        conn2 = _Connection({})
-        CLIENT2 = _Client(project=self.PROJECT, connection=conn2)
-        dataset = self._make_one(self.DS_ID, client=CLIENT1)
-
-        self.assertTrue(dataset.exists(client=CLIENT2))
-
-        self.assertEqual(len(conn1._requested), 0)
-        self.assertEqual(len(conn2._requested), 1)
-        req = conn2._requested[0]
-        self.assertEqual(req['method'], 'GET')
-        self.assertEqual(req['path'], '/%s' % PATH)
-        self.assertEqual(req['query_params'], {'fields': 'id'})
-
     def test_patch_w_invalid_expiration(self):
         RESOURCE = self._makeResource()
         conn = _Connection(RESOURCE)
@@ -727,13 +696,6 @@ def __init__(self, *responses):
         self._requested = []
 
     def api_request(self, **kw):
-        from google.cloud.exceptions import NotFound
-
         self._requested.append(kw)
-
-        try:
-            response, self._responses = self._responses[0], self._responses[1:]
-        except IndexError:
-            raise NotFound('miss')
-        else:
-            return response
+        response, self._responses = self._responses[0], self._responses[1:]
+        return response