Change checks for handling same layer name un different stack

moto/opsworks/models.py

@@ -422,11 +422,11 @@ class OpsWorksBackend(BaseBackend):
         stackid = kwargs['stack_id']
         if stackid not in self.stacks:
             raise ResourceNotFoundException(stackid)
-        if name in [l.name for l in self.layers.values()]:
+        if name in [l.name for l in self.stacks[stackid].layers]:
             raise ValidationException(
                 'There is already a layer named "{0}" '
                 'for this stack'.format(name))
-        if shortname in [l.shortname for l in self.layers.values()]:
+        if shortname in [l.shortname for l in self.stacks[stackid].layers]:
             raise ValidationException(
                 'There is already a layer with shortname "{0}" '
                 'for this stack'.format(shortname))

tests/test_opsworks/test_layers.py

@@ -24,16 +24,16 @@ def test_create_layer_response():
         Name="TestLayer",
         Shortname="TestLayerShortName"
     )
-    
+
     response.should.contain("LayerId")
-    
+
     second_stack_id = client.create_stack(
         Name="test_stack_2",
         Region="us-east-1",
         ServiceRoleArn="service_arn",
         DefaultInstanceProfileArn="profile_arn"
     )['StackId']
-    
+
     response = client.create_layer(
         StackId=second_stack_id,
         Type="custom",