Add support for IoT detach_policy

IMPLEMENTATION_COVERAGE.md

@@ -2376,7 +2376,7 @@
 - [ ] unsubscribe_from_event
 - [ ] update_assessment_target
 
-## iot - 31% implemented
+## iot - 32% implemented
 - [ ] accept_certificate_transfer
 - [X] add_thing_to_thing_group
 - [ ] associate_targets_with_job
@@ -2429,7 +2429,7 @@
 - [X] describe_thing_group
 - [ ] describe_thing_registration_task
 - [X] describe_thing_type
-- [ ] detach_policy
+- [X] detach_policy
 - [X] detach_principal_policy
 - [X] detach_thing_principal
 - [ ] disable_topic_rule

moto/iot/models.py

@@ -445,6 +445,15 @@ class IoTBackend(BaseBackend):
             return
         self.principal_policies[k] = (principal, policy)
 
+    def detach_policy(self, policy_name, target):
+        # this may raises ResourceNotFoundException
+        self._get_principal(target)
+        self.get_policy(policy_name)
+        k = (target, policy_name)
+        if k not in self.principal_policies:
+            raise ResourceNotFoundException()
+        del self.principal_policies[k]
+
     def detach_principal_policy(self, policy_name, principal_arn):
         # this may raises ResourceNotFoundException
         self._get_principal(principal_arn)

moto/iot/responses.py

@@ -242,6 +242,15 @@ class IoTResponse(BaseResponse):
         )
         return json.dumps(dict())
 
+    def detach_policy(self):
+        policy_name = self._get_param("policyName")
+        target = self._get_param('target')
+        self.iot_backend.detach_policy(
+            policy_name=policy_name,
+            target=target,
+        )
+        return json.dumps(dict())
+
     def detach_principal_policy(self):
         policy_name = self._get_param("policyName")
         principal = self.headers.get('x-amzn-iot-principal')

tests/test_iot/test_iot.py

@@ -5,6 +5,8 @@ import sure  # noqa
 import boto3
 
 from moto import mock_iot
+from botocore.exceptions import ClientError
+from nose.tools import assert_raises
 
 
 @mock_iot
@@ -338,11 +340,14 @@ def test_principal_policy():
     for principal in res['principals']:
         principal.should_not.be.none
 
-    client.detach_principal_policy(policyName=policy_name, principal=cert_arn)
+    client.detach_policy(policyName=policy_name, target=cert_arn)
     res = client.list_principal_policies(principal=cert_arn)
     res.should.have.key('policies').which.should.have.length_of(0)
     res = client.list_policy_principals(policyName=policy_name)
     res.should.have.key('principals').which.should.have.length_of(0)
+    with assert_raises(ClientError) as e:
+        client.detach_policy(policyName=policy_name, target=cert_arn)
+    e.exception.response['Error']['Code'].should.equal('ResourceNotFoundException')
 
 
 @mock_iot