Add missing changes when creating a change set (#3039)

* Display changes when creating a change set

* add change set id and description when describing stack

* fix lint with flake8 and black

tests/test_cloudformation/test_cloudformation_stack_crud_boto3.py

@@ -573,9 +573,9 @@ def test_boto3_create_stack_set_with_yaml():
 def test_create_stack_set_from_s3_url():
     s3 = boto3.client("s3")
     s3_conn = boto3.resource("s3", region_name="us-east-1")
-    bucket = s3_conn.create_bucket(Bucket="foobar")
+    s3_conn.create_bucket(Bucket="foobar")
 
-    key = s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
+    s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
     key_url = s3.generate_presigned_url(
         ClientMethod="get_object", Params={"Bucket": "foobar", "Key": "template-key"}
     )
@@ -716,9 +716,9 @@ def test_create_stack_with_role_arn():
 def test_create_stack_from_s3_url():
     s3 = boto3.client("s3")
     s3_conn = boto3.resource("s3", region_name="us-east-1")
-    bucket = s3_conn.create_bucket(Bucket="foobar")
+    s3_conn.create_bucket(Bucket="foobar")
 
-    key = s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
+    s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
     key_url = s3.generate_presigned_url(
         ClientMethod="get_object", Params={"Bucket": "foobar", "Key": "template-key"}
     )
@@ -800,9 +800,9 @@ def test_update_stack_from_s3_url():
 def test_create_change_set_from_s3_url():
     s3 = boto3.client("s3")
     s3_conn = boto3.resource("s3", region_name="us-east-1")
-    bucket = s3_conn.create_bucket(Bucket="foobar")
+    s3_conn.create_bucket(Bucket="foobar")
 
-    key = s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
+    s3_conn.Object("foobar", "template-key").put(Body=dummy_template_json)
     key_url = s3.generate_presigned_url(
         ClientMethod="get_object", Params={"Bucket": "foobar", "Key": "template-key"}
     )
@@ -844,6 +844,25 @@ def test_describe_change_set():
     assert (
         two_secs_ago < stack["CreationTime"] < datetime.now(tz=pytz.UTC)
     ), "Change set should have been created recently"
+    stack["Changes"].should.have.length_of(1)
+    stack["Changes"][0].should.equal(
+        dict(
+            {
+                "Type": "Resource",
+                "ResourceChange": {
+                    "Action": "Add",
+                    "LogicalResourceId": "EC2Instance1",
+                    "ResourceType": "AWS::EC2::Instance",
+                },
+            }
+        )
+    )
+
+    # Execute change set
+    cf_conn.execute_change_set(ChangeSetName="NewChangeSet")
+    # Verify that the changes have been applied
+    stack = cf_conn.describe_change_set(ChangeSetName="NewChangeSet")
+    stack["Changes"].should.have.length_of(1)
 
     cf_conn.create_change_set(
         StackName="NewStack",
@@ -887,7 +906,7 @@ def test_execute_change_set_w_arn():
 @mock_cloudformation
 def test_execute_change_set_w_name():
     cf_conn = boto3.client("cloudformation", region_name="us-east-1")
-    change_set = cf_conn.create_change_set(
+    cf_conn.create_change_set(
         StackName="NewStack",
         TemplateBody=dummy_template_json,
         ChangeSetName="NewChangeSet",
@@ -1221,9 +1240,7 @@ def test_delete_stack_with_export():
 @mock_cloudformation
 def test_export_names_must_be_unique():
     cf = boto3.resource("cloudformation", region_name="us-east-1")
-    first_stack = cf.create_stack(
-        StackName="test_stack", TemplateBody=dummy_output_template_json
-    )
+    cf.create_stack(StackName="test_stack", TemplateBody=dummy_output_template_json)
     with assert_raises(ClientError):
         cf.create_stack(StackName="test_stack", TemplateBody=dummy_output_template_json)
 
@@ -1237,9 +1254,7 @@ def test_stack_with_imports():
     output_stack = cf.create_stack(
         StackName="test_stack1", TemplateBody=dummy_output_template_json
     )
-    import_stack = cf.create_stack(
-        StackName="test_stack2", TemplateBody=dummy_import_template_json
-    )
+    cf.create_stack(StackName="test_stack2", TemplateBody=dummy_import_template_json)
 
     output_stack.outputs.should.have.length_of(1)
     output = output_stack.outputs[0]["OutputValue"]

tests/test_cloudformation/test_cloudformation_stack_integration.py

@@ -1,7 +1,6 @@
 from __future__ import unicode_literals
 import json
 
-import base64
 from decimal import Decimal
 
 import boto
@@ -28,7 +27,6 @@ from moto import (
     mock_dynamodb2,
     mock_ec2,
     mock_ec2_deprecated,
-    mock_elb,
     mock_elb_deprecated,
     mock_events,
     mock_iam_deprecated,
@@ -37,18 +35,14 @@ from moto import (
     mock_logs,
     mock_rds_deprecated,
     mock_rds2,
-    mock_rds2_deprecated,
-    mock_redshift,
     mock_redshift_deprecated,
     mock_route53_deprecated,
     mock_s3,
     mock_sns_deprecated,
-    mock_sqs,
     mock_sqs_deprecated,
     mock_elbv2,
 )
 from moto.core import ACCOUNT_ID
-from moto.dynamodb2.models import Table
 
 from tests.test_cloudformation.fixtures import (
     ec2_classic_eip,