Adding un-implemented ConnectionPool.connection.

Simply added to match interface, implementation will be forthcoming.

gcloud_bigtable/happybase/pool.py

@@ -69,3 +69,18 @@ def __init__(self, size, **kwargs):
         for _ in xrange(size):
             connection = Connection(**connection_kwargs)
             self._queue.put(connection)
+
+    def connection(self, timeout=None):
+        """Obtain a connection from the pool.
+
+        Intended to be used as a context manager, but not implemented with
+        that functionality yet.
+
+        :type timeout: int
+        :param timeout: (Optional) Time (in seconds) to wait for a connection
+                        to open.
+
+        :raises: :class:`NotImplementedError <exceptions.NotImplementedError>`
+                 temporarily until the method is implemented.
+        """
+        raise NotImplementedError('Temporarily not implemented.')

gcloud_bigtable/happybase/test_pool.py

@@ -98,3 +98,10 @@ def test_constructor_non_positive_size(self):
         size = 0
         with self.assertRaises(ValueError):
             self._makeOne(size)
+
+    def test_connection(self):
+        size = 1
+        timeout = 10
+        pool = self._makeOne(size)
+        with self.assertRaises(NotImplementedError):
+            pool.connection(timeout=timeout)