Autoscaling: update_group() now validates that the Group exists (#7983)

moto/autoscaling/models.py

@@ -1171,6 +1171,8 @@ def update_auto_scaling_group(
                 "Valid requests must contain either LaunchTemplate, LaunchConfigurationName "
                 "or MixedInstancesPolicy parameter."
             )
+        if name not in self.autoscaling_groups:
+            raise ValidationError("AutoScalingGroup name not found - null")
 
         group = self.autoscaling_groups[name]
         group.update(

tests/test_autoscaling/test_autoscaling.py

@@ -7,7 +7,7 @@
 
 from moto import mock_aws
 from moto.core import DEFAULT_ACCOUNT_ID as ACCOUNT_ID
-from tests import EXAMPLE_AMI_ID
+from tests import EXAMPLE_AMI_ID, aws_verified
 
 from .utils import setup_instance_with_networking, setup_networking
 
@@ -651,6 +651,22 @@ def test_update_autoscaling_group_max_size_desired_capacity_change():
     assert len(group["Instances"]) == 5
 
 
+@aws_verified
+@pytest.mark.aws_verified
+def test_update_unknown_group():
+    client = boto3.client("autoscaling", region_name="us-east-1")
+    with pytest.raises(ClientError) as exc:
+        client.update_auto_scaling_group(
+            AutoScalingGroupName="fake-asg",
+            MinSize=2,
+            MaxSize=2,
+            DesiredCapacity=2,
+        )
+    err = exc.value.response["Error"]
+    assert err["Code"] == "ValidationError"
+    assert err["Message"] == "AutoScalingGroup name not found - null"
+
+
 @mock_aws
 def test_autoscaling_describe_policies():
     mocked_networking = setup_networking()