def METHOD_NAME(user_name="test-user"):
    """
    Should create a user with attached policy allowing read/write operations on S3.
    """
    policy_document = {
        "Version": "2012-10-17",
        "Statement": [{"Effect": "Allow", "Action": "s3:*", "Resource": "*"}],
    }
    # Create client and user
    client = boto3.client("iam", region_name="us-east-1")
    client.create_user(UserName=user_name)
    # Create and attach the policy
    policy_arn = client.create_policy(
        PolicyName="policy1", PolicyDocument=json.dumps(policy_document)
    )["Policy"]["Arn"]
    client.attach_user_policy(UserName=user_name, PolicyArn=policy_arn)
    # Return the access keys
    return client.create_access_key(UserName=user_name)["AccessKey"]