subms 0.2.1

Zero-dependency perf-test harness for Rust: timed stages, percentiles, and a stable JSON shape consumed by the submillisecond.com cookbook. Includes a `Recipe` trait for cookbook benchmarks.
Documentation 
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use subms::PerfHarness;

#[test]
fn round_trip_smoke() {
    let mut h = PerfHarness::new("toy", "rust");
    h.input("entries", "1000");
    h.input("bloom_mode", "on");
    h.meta("sstables", "1");

    let s = h.stage("work", 1000);
    for i in 0..1000u64 {
        s.record(i * 10);
    }

    let mut buf = Vec::new();
    h.write_json(&mut buf).unwrap();
    let json = String::from_utf8(buf).unwrap();

    assert!(json.starts_with('{'));
    assert!(json.contains("\"workload\":\"toy\""));
    assert!(json.contains("\"lang\":\"rust\""));
    assert!(json.contains("\"inputs\""));
    assert!(json.contains("\"entries\":\"1000\""));
    assert!(json.contains("\"work\":{"));
    assert!(json.contains("\"count\":1000"));
    assert!(json.contains("\"samples_ns\":["));
}

#[test]
fn percentiles_make_sense() {
    let mut h = PerfHarness::new("perc", "rust");
    let s = h.stage("op", 100);
    for i in 0..100u64 {
        s.record(i);
    }

    let mut buf = Vec::new();
    h.write_json(&mut buf).unwrap();
    let json = String::from_utf8(buf).unwrap();

    // For samples 0..100, p50 ≈ 50, p99 ≈ 99, max = 99.
    assert!(json.contains("\"p50_ns\":50"));
    assert!(json.contains("\"max_ns\":99"));
}