Better reliability for flaky tests [(#1960)](GoogleCloudPlatform/pyth…

…on-docs-samples#1960)

* Increases reliability for flaky tests
* Replaces checks where device or gateway ID could affect test outcome.

samples/api-client/manager/manager_test.py

@@ -18,6 +18,7 @@
 
 # Add command receiver for bootstrapping device registry / device for testing
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'mqtt_example'))  # noqa
+from gcp_devrel.testing.flaky import flaky
 from google.cloud import pubsub
 import pytest
 
@@ -278,14 +279,24 @@ def test_add_patch_delete_es256(test_topic, capsys):
             service_account_json, project_id, cloud_region, registry_id)
 
 
+@flaky
 def test_send_command(test_topic, capsys):
     device_id = device_id_template.format('RSA256')
     manager.create_registry(
             service_account_json, project_id, cloud_region, pubsub_topic,
             registry_id)
-    manager.create_rs256_device(
-            service_account_json, project_id, cloud_region, registry_id,
-            device_id, rsa_cert_path)
+
+    exists = False
+    devices = manager.list_devices(
+            service_account_json, project_id, cloud_region, registry_id)
+    for device in devices:
+        if device.get('id') == device_id:
+            exists = True
+
+    if not exists:
+        manager.create_rs256_device(
+                service_account_json, project_id, cloud_region, registry_id,
+                device_id, rsa_cert_path)
 
     # Exercize the functionality
     client = cloudiot_mqtt_example.get_client(

samples/api-client/manager/requirements.txt

@@ -1,4 +1,6 @@
 cryptography==2.4.2
+flaky==3.4.0
+gcp-devrel-py-tools==0.0.15
 google-api-python-client==1.7.5
 google-auth-httplib2==0.0.3
 google-auth==1.6.1