feat: add support for using the emulator programatically

google/cloud/spanner_v1/client.py

@@ -28,6 +28,7 @@
 import warnings
 
 from google.api_core.gapic_v1 import client_info
+from google.auth.credentials import AnonymousCredentials
 import google.api_core.client_options
 
 from google.cloud.spanner_admin_instance_v1.gapic.transports import (
@@ -173,19 +174,27 @@ def __init__(
         client_options=None,
         query_options=None,
     ):
+        self._emulator_host = _get_spanner_emulator_host()
+
+        if client_options and type(client_options) == dict:
+            self._client_options = google.api_core.client_options.from_dict(
+                client_options
+            )
+        else:
+            self._client_options = client_options
+
+        if self._emulator_host:
+            credentials = AnonymousCredentials()
+        elif isinstance(credentials, AnonymousCredentials):
+            self._emulator_host = self._client_options.api_endpoint
+
         # NOTE: This API has no use for the _http argument, but sending it
         #       will have no impact since the _http() @property only lazily
         #       creates a working HTTP object.
         super(Client, self).__init__(
             project=project, credentials=credentials, _http=None
         )
         self._client_info = client_info
-        if client_options and type(client_options) == dict:
-            self._client_options = google.api_core.client_options.from_dict(
-                client_options
-            )
-        else:
-            self._client_options = client_options
 
         env_query_options = ExecuteSqlRequest.QueryOptions(
             optimizer_version=_get_spanner_optimizer_version()
@@ -198,9 +207,8 @@ def __init__(
             warnings.warn(_USER_AGENT_DEPRECATED, DeprecationWarning, stacklevel=2)
             self.user_agent = user_agent
 
-        if _get_spanner_emulator_host() is not None and (
-            "http://" in _get_spanner_emulator_host()
-            or "https://" in _get_spanner_emulator_host()
+        if self._emulator_host is not None and (
+            "http://" in self._emulator_host or "https://" in self._emulator_host
         ):
             warnings.warn(_EMULATOR_HOST_HTTP_SCHEME)
 
@@ -237,9 +245,9 @@ def project_name(self):
     def instance_admin_api(self):
         """Helper for session-related API calls."""
         if self._instance_admin_api is None:
-            if _get_spanner_emulator_host() is not None:
+            if self._emulator_host is not None:
                 transport = instance_admin_grpc_transport.InstanceAdminGrpcTransport(
-                    channel=grpc.insecure_channel(_get_spanner_emulator_host())
+                    channel=grpc.insecure_channel(target=self._emulator_host)
                 )
                 self._instance_admin_api = InstanceAdminClient(
                     client_info=self._client_info,
@@ -258,9 +266,9 @@ def instance_admin_api(self):
     def database_admin_api(self):
         """Helper for session-related API calls."""
         if self._database_admin_api is None:
-            if _get_spanner_emulator_host() is not None:
+            if self._emulator_host is not None:
                 transport = database_admin_grpc_transport.DatabaseAdminGrpcTransport(
-                    channel=grpc.insecure_channel(_get_spanner_emulator_host())
+                    channel=grpc.insecure_channel(target=self._emulator_host)
                 )
                 self._database_admin_api = DatabaseAdminClient(
                     client_info=self._client_info,
@@ -363,7 +371,7 @@ def instance(
             configuration_name,
             node_count,
             display_name,
-            _get_spanner_emulator_host(),
+            self._emulator_host,
         )
 
     def list_instances(self, filter_="", page_size=None, page_token=None):

google/cloud/spanner_v1/database.py

@@ -223,9 +223,7 @@ def spanner_api(self):
                     channel=grpc.insecure_channel(self._instance.emulator_host)
                 )
                 self._spanner_api = SpannerClient(
-                    client_info=client_info,
-                    client_options=client_options,
-                    transport=transport,
+                    client_info=client_info, transport=transport
                 )
                 return self._spanner_api
             credentials = self._instance._client.credentials

tests/unit/test_client.py

@@ -110,11 +110,14 @@ def _constructor_test_helper(
     @mock.patch("warnings.warn")
     def test_constructor_emulator_host_warning(self, mock_warn, mock_em):
         from google.cloud.spanner_v1 import client as MUT
+        from google.auth.credentials import AnonymousCredentials
 
-        expected_scopes = (MUT.SPANNER_ADMIN_SCOPE,)
+        expected_scopes = None
         creds = _make_credentials()
         mock_em.return_value = "http://emulator.host.com"
-        self._constructor_test_helper(expected_scopes, creds)
+        with mock.patch("google.cloud.spanner_v1.client.AnonymousCredentials") as patch:
+            expected_creds = patch.return_value = AnonymousCredentials()
+            self._constructor_test_helper(expected_scopes, creds, expected_creds)
         mock_warn.assert_called_once_with(MUT._EMULATOR_HOST_HTTP_SCHEME)
 
     def test_constructor_default_scopes(self):
@@ -219,6 +222,8 @@ def test_constructor_custom_query_options_env_config(self, mock_ver):
     def test_instance_admin_api(self, mock_em):
         from google.cloud.spanner_v1.client import SPANNER_ADMIN_SCOPE
 
+        mock_em.return_value = None
+
         credentials = _make_credentials()
         client_info = mock.Mock()
         client_options = mock.Mock()
@@ -230,7 +235,6 @@ def test_instance_admin_api(self, mock_em):
         )
         expected_scopes = (SPANNER_ADMIN_SCOPE,)
 
-        mock_em.return_value = None
         inst_module = "google.cloud.spanner_v1.client.InstanceAdminClient"
         with mock.patch(inst_module) as instance_admin_client:
             api = client.instance_admin_api
@@ -250,7 +254,8 @@ def test_instance_admin_api(self, mock_em):
         credentials.with_scopes.assert_called_once_with(expected_scopes)
 
     @mock.patch("google.cloud.spanner_v1.client._get_spanner_emulator_host")
-    def test_instance_admin_api_emulator(self, mock_em):
+    def test_instance_admin_api_emulator_env(self, mock_em):
+        mock_em.return_value = "emulator.host"
         credentials = _make_credentials()
         client_info = mock.Mock()
         client_options = mock.Mock()
@@ -261,7 +266,38 @@ def test_instance_admin_api_emulator(self, mock_em):
             client_options=client_options,
         )
 
-        mock_em.return_value = "true"
+        inst_module = "google.cloud.spanner_v1.client.InstanceAdminClient"
+        with mock.patch(inst_module) as instance_admin_client:
+            api = client.instance_admin_api
+
+        self.assertIs(api, instance_admin_client.return_value)
+
+        # API instance is cached
+        again = client.instance_admin_api
+        self.assertIs(again, api)
+
+        self.assertEqual(len(instance_admin_client.call_args_list), 1)
+        called_args, called_kw = instance_admin_client.call_args
+        self.assertEqual(called_args, ())
+        self.assertEqual(called_kw["client_info"], client_info)
+        self.assertEqual(called_kw["client_options"], client_options)
+        self.assertIn("transport", called_kw)
+        self.assertNotIn("credentials", called_kw)
+
+    def test_instance_admin_api_emulator_code(self):
+        from google.auth.credentials import AnonymousCredentials
+        from google.api_core.client_options import ClientOptions
+
+        credentials = AnonymousCredentials()
+        client_info = mock.Mock()
+        client_options = ClientOptions(api_endpoint="emulator.host")
+        client = self._make_one(
+            project=self.PROJECT,
+            credentials=credentials,
+            client_info=client_info,
+            client_options=client_options,
+        )
+
         inst_module = "google.cloud.spanner_v1.client.InstanceAdminClient"
         with mock.patch(inst_module) as instance_admin_client:
             api = client.instance_admin_api
@@ -284,6 +320,7 @@ def test_instance_admin_api_emulator(self, mock_em):
     def test_database_admin_api(self, mock_em):
         from google.cloud.spanner_v1.client import SPANNER_ADMIN_SCOPE
 
+        mock_em.return_value = None
         credentials = _make_credentials()
         client_info = mock.Mock()
         client_options = mock.Mock()
@@ -295,7 +332,6 @@ def test_database_admin_api(self, mock_em):
         )
         expected_scopes = (SPANNER_ADMIN_SCOPE,)
 
-        mock_em.return_value = None
         db_module = "google.cloud.spanner_v1.client.DatabaseAdminClient"
         with mock.patch(db_module) as database_admin_client:
             api = client.database_admin_api
@@ -315,7 +351,8 @@ def test_database_admin_api(self, mock_em):
         credentials.with_scopes.assert_called_once_with(expected_scopes)
 
     @mock.patch("google.cloud.spanner_v1.client._get_spanner_emulator_host")
-    def test_database_admin_api_emulator(self, mock_em):
+    def test_database_admin_api_emulator_env(self, mock_em):
+        mock_em.return_value = "host:port"
         credentials = _make_credentials()
         client_info = mock.Mock()
         client_options = mock.Mock()
@@ -326,7 +363,38 @@ def test_database_admin_api_emulator(self, mock_em):
             client_options=client_options,
         )
 
-        mock_em.return_value = "host:port"
+        db_module = "google.cloud.spanner_v1.client.DatabaseAdminClient"
+        with mock.patch(db_module) as database_admin_client:
+            api = client.database_admin_api
+
+        self.assertIs(api, database_admin_client.return_value)
+
+        # API instance is cached
+        again = client.database_admin_api
+        self.assertIs(again, api)
+
+        self.assertEqual(len(database_admin_client.call_args_list), 1)
+        called_args, called_kw = database_admin_client.call_args
+        self.assertEqual(called_args, ())
+        self.assertEqual(called_kw["client_info"], client_info)
+        self.assertEqual(called_kw["client_options"], client_options)
+        self.assertIn("transport", called_kw)
+        self.assertNotIn("credentials", called_kw)
+
+    def test_database_admin_api_emulator_code(self):
+        from google.auth.credentials import AnonymousCredentials
+        from google.api_core.client_options import ClientOptions
+
+        credentials = AnonymousCredentials()
+        client_info = mock.Mock()
+        client_options = ClientOptions(api_endpoint="emulator.host")
+        client = self._make_one(
+            project=self.PROJECT,
+            credentials=credentials,
+            client_info=client_info,
+            client_options=client_options,
+        )
+
         db_module = "google.cloud.spanner_v1.client.DatabaseAdminClient"
         with mock.patch(db_module) as database_admin_client:
             api = client.database_admin_api