It is my understanding that setting an environment varialbe `TEST_AWS_ACCOUNT_ID` for localstack sets that as the AWS account for the user in localstack.

However, setting it does not actually change any ARNs. For example:

1. Start localstack using `TEST_AWS_ACCOUNT_ID="111111111111" DEBUG=1 localstack start`
2. Deploy anything with an ARN (in this example I deployed a lambda)
3. Check the ARN. Example output for lambda:
```json
$ awslocal lambda list-functions
{
    "Functions": [
        {
            "FunctionName": "localtest-local-hello",
            "FunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:localtest-local-hello",
            "Runtime": "nodejs10.x",
            "Role": "test_role",
            "Handler": "handler.hello",
            "CodeSize": 3077,
            "Description": "",
            "Timeout": 6,
            "MemorySize": 1024,
            "LastModified": "2019-11-06T06:43:53.451+0000",
            "CodeSha256": "V77gR13o90ET7+XquXBBc3Rxr1qDu1bE7S+A0Wbx5ys=",
            "Version": "$LATEST",
            "TracingConfig": {
                "Mode": "PassThrough"
            },
            "RevisionId": "3d4ed679-c1a9-4b7e-ad9e-f27e8543c5e9"
        }
    ]
}
```

ARN is still 000000000000
for resource_id, resource in iteritems(resources):
        if is_deployable_resource(resource):
            if not is_deployed(resource_id, all_resources, stack_name):
                return False
    return True
def resources_to_deploy_next(resources, stack_name):
    result = {}
    for resource_id, resource in iteritems(resources):
        if should_be_deployed(resource_id, resources, stack_name):
            result[resource_id] = resource
    return result
def get_resource_dependencies(resource_id, resource, resources):
    result = {}
    dumped = json.dumps(common.json_safe(resource))
    for other_id, other in iteritems(resources):
        if resource != other:
            
            search1 = '{"Ref": "%s"}' % other_id
            search2 = '{"Fn::GetAtt": ["%s", ' % other_id
            if search1 in dumped or search2 in dumped:
                result[other_id] = other
            if other_id in resource.get('DependsOn', []):
                result[other_id] = other
    return result