Modifying AWS resource for testing

 If you are writing unit tests using boto3 and moto, you might want to modify a value in a resource. I had this case, for instance, where I wanted to set the state of an AMI to pending for a test. Using moto, AMIs are always created in the available state. However, if you try to do it this way, it will fail:

ec2 = boto3.resource("ec2")

image = ec2.Image(AMI_ID)

image.state = "pending"

You will end up with this message:

AttributeError: can't set attribute 'state'

It is possible to modify the resource object. However, it will just modify this object instance, the model itself will not be updated. So if you use the resource as a parameter to a function, it will work. But if the function retrieves its data with boto3, it will get the original value.

Here is my solution:

image.meta.data.update({"State": "pending"})

That helped in my case.