#[test]
fn csv_duplicate_header_is_invalid_input() {
let yaml = r#"
version: 2
input:
format: csv
csv:
has_header: true
mappings:
- target: "id"
source: "id"
"#;
let rule = parse_rule_file(yaml).expect("parse rule");
let err = transform(&rule, "id,id\n1,2\n", None).expect_err("duplicate header should fail");
assert_eq!(err.kind, TransformErrorKind::InvalidInput);
}