chore(tests): system tests support emulator

tests/system/data/setup_fixtures.py

@@ -35,17 +35,31 @@ def event_loop():
 def instance_admin_client():
     """Client for interacting with the Instance Admin API."""
     from google.cloud.bigtable_admin_v2 import BigtableInstanceAdminClient
+    from google.cloud.environment_vars import BIGTABLE_EMULATOR  # type: ignore
+    import google.auth.credentials
 
-    with BigtableInstanceAdminClient() as client:
+    # check for emulator mode
+    credentials = None
+    if os.getenv(BIGTABLE_EMULATOR) is not None:
+        credentials = google.auth.credentials.AnonymousCredentials()
+
+    with BigtableInstanceAdminClient(credentials=credentials) as client:
         yield client
 
 
 @pytest.fixture(scope="session")
 def table_admin_client():
     """Client for interacting with the Table Admin API."""
     from google.cloud.bigtable_admin_v2 import BigtableTableAdminClient
+    from google.cloud.environment_vars import BIGTABLE_EMULATOR
+    import google.auth.credentials
+
+    # check for emulator mode
+    credentials = None
+    if os.getenv(BIGTABLE_EMULATOR) is not None:
+        credentials = google.auth.credentials.AnonymousCredentials()
 
-    with BigtableTableAdminClient() as client:
+    with BigtableTableAdminClient(credentials=credentials) as client:
         yield client