test(app): add manual performance diagnostics (#32937)

2026-06-19 19:39:02 +02:00
parent 10ec856ff2
commit c6083a474c
26 changed files with 2656 additions and 3 deletions
@@ -0,0 +1,42 @@
+import { expect, test } from "bun:test"
+import { compressCachedRepaintTrace, layoutShiftSample } from "../timeline/session-tab-repaint-probe"
+
+test("compresses repeated repaint states without losing frame samples", () => {
+  const state = {
+    root: 1,
+    scrollTop: 10,
+    scrollHeight: 20,
+    bottomErrorPx: 0,
+    last: true,
+    rows: [{ key: "row", node: 2, top: 0, bottom: 10 }],
+    mounted: 1,
+    center: "content",
+  }
+  const trace = {
+    timeOriginEpochMs: 1_000,
+    startedAtPerformanceMs: 100,
+    samples: [
+      { observedAtMs: 16, ...state, destination: ["target"], source: [] },
+      { observedAtMs: 32, ...state, destination: ["target"], source: [] },
+      { observedAtMs: 48, ...state, scrollTop: 11, destination: ["target"], source: [] },
+    ],
+    mutations: [{ observedAtMs: 20, changed: [{ type: "add", node: 2 }] }],
+    shifts: [{ occurredAtMs: 24, value: 0.1 }],
+    windowMs: 1_000,
+    running: false,
+    stop() {},
+  }
+  const compressed = compressCachedRepaintTrace(trace)
+  const samples = compressed.samples.flatMap((group) =>
+    group.observedAtMs.map((observedAtMs) => ({ observedAtMs, ...group.state })),
+  )
+
+  expect(samples).toEqual(trace.samples)
+  expect(compressed.mutations).toEqual(trace.mutations)
+  expect(compressed.shifts).toEqual(trace.shifts)
+})
+
+test("records layout shifts at occurrence time within the probe window", () => {
+  expect(layoutShiftSample({ startTime: 99, value: 0.1 }, 100)).toBeUndefined()
+  expect(layoutShiftSample({ startTime: 124, value: 0.2 }, 100)).toEqual({ occurredAtMs: 24, value: 0.2 })
+})