Add set_delete_after_tag as a parameter on ResourceGroupPreparer (#11749

)

* Add set_delete_after_tag as a parameter on ResourceGroupPreparer so that test-prepared RGs can be automatically cleaned up by engsys.
* Populate this into the two "default helper RG preparers" (randomized/cached) to implicitly opt-in the tests consuming those into the best practice. (Currently this is a very limited set of SDKs)
* Make delete_after_tag take a timespan and be enabled by default.

tools/azure-sdk-tools/devtools_testutils/resource_testcase.py

@@ -6,6 +6,7 @@
 from collections import namedtuple
 import functools
 import os
+import datetime
 from functools import partial
 
 from azure_devtools.scenario_tests import AzureTestError, ReservedResourceNameError
@@ -33,7 +34,8 @@ def __init__(self, name_prefix='',
                  parameter_name_for_location='location', location='westus',
                  disable_recording=True, playback_fake_resource=None,
                  client_kwargs=None,
-                 random_name_enabled=False):
+                 random_name_enabled=False,
+                 delete_after_tag_timedelta=datetime.timedelta(days=1)):
         super(ResourceGroupPreparer, self).__init__(name_prefix, random_name_length,
                                                     disable_recording=disable_recording,
                                                     playback_fake_resource=playback_fake_resource,
@@ -50,13 +52,18 @@ def __init__(self, name_prefix='',
         if self.random_name_enabled:
             self.resource_moniker = self.name_prefix + "rgname"
         self.set_cache(use_cache, parameter_name)
+        self.delete_after_tag_timedelta = delete_after_tag_timedelta
 
     def create_resource(self, name, **kwargs):
         if self.is_live and self._need_creation:
             self.client = self.create_mgmt_client(ResourceManagementClient)
+            parameters = {'location': self.location}
+            if self.delete_after_tag_timedelta:
+                expiry = datetime.datetime.utcnow() + self.delete_after_tag_timedelta
+                parameters['tags'] = {'DeleteAfter': expiry.isoformat()}
             try:
                 self.resource = self.client.resource_groups.create_or_update(
-                    name, {'location': self.location}
+                    name, parameters
                 )
             except Exception as ex:
                 if "ReservedResourceName" in str(ex):
@@ -92,4 +99,4 @@ def remove_resource(self, name, **kwargs):
                 pass
 
 RandomNameResourceGroupPreparer = partial(ResourceGroupPreparer, random_name_enabled=True)
-CachedResourceGroupPreparer = functools.partial(ResourceGroupPreparer, use_cache=True, random_name_enabled=True)
+CachedResourceGroupPreparer = partial(ResourceGroupPreparer, use_cache=True, random_name_enabled=True)