//! Integration guard for the `aura chart` viewer's gap handling under a
//! multi-cadence (union-spine null-filled) trace.
//!
//! The CLI aligns taps that fire at different cadences onto a shared union x-axis
//! by null-filling the timestamps a tap did not fire at (spec 0056 §6). The
//! property "those nulls reach uPlot's data array verbatim — a gap, never dropped,
//! never coerced to 0" lives in `chart-viewer.js`, so it cannot be checked from
//! Rust. This shells out to `node`, running `tests/chart_viewer_gaps.mjs`, which
//! loads the real viewer module and drives the pure `buildCharts` over a sparse
//! fixture. `node` is REQUIRED: if absent this test FAILS.

use std::path::PathBuf;
use std::process::Command;

#[test]
fn chart_viewer_preserves_union_spine_null_gaps() {
    let script = PathBuf::from(env!("CARGO_MANIFEST_DIR"))
        .join("tests")
        .join("chart_viewer_gaps.mjs");
    assert!(script.exists(), "guard script missing at {}", script.display());

    let out = match Command::new("node").arg(&script).output() {
        Ok(out) => out,
        Err(e) => panic!(
            "node is required for the chart-viewer gap guard but could not be run \
             ({e}); install Node.js or ensure `node` is on PATH"
        ),
    };

    let stdout = String::from_utf8_lossy(&out.stdout);
    let stderr = String::from_utf8_lossy(&out.stderr);
    assert!(
        out.status.success(),
        "chart-viewer gap guard failed (exit {:?}).\n--- node stdout ---\n{stdout}\n--- node stderr ---\n{stderr}",
        out.status.code()
    );
}