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| import { describe, expect, it, vi } from "vitest"; | |
| import { getPageReadStats, recordPageRead } from "./pageReadsSinceLastRestart"; | |
| /** | |
| * The counters live for the process, so every case measures a delta rather | |
| * than an absolute, which is also how they are read in production. | |
| */ | |
| function delta(run: () => void) { | |
| const before = getPageReadStats(); | |
| run(); | |
| const after = getPageReadStats(); | |
| return { | |
| requested: after.requested - before.requested, | |
| read: after.read - before.read, | |
| bodiesTruncated: after.bodiesTruncated - before.bodiesTruncated, | |
| skipped: Object.fromEntries( | |
| Object.entries(after.skipped).map(([outcome, count]) => [ | |
| outcome, | |
| count - before.skipped[outcome as keyof typeof before.skipped], | |
| ]), | |
| ), | |
| after, | |
| }; | |
| } | |
| describe("recordPageRead", () => { | |
| it("counts a successful read", () => { | |
| const counted = delta(() => | |
| recordPageRead({ outcome: "read", durationMs: 100 }), | |
| ); | |
| expect(counted.requested).toBe(1); | |
| expect(counted.read).toBe(1); | |
| }); | |
| it("counts every outcome against the total requested", () => { | |
| const counted = delta(() => { | |
| recordPageRead({ outcome: "blocked", durationMs: 1 }); | |
| recordPageRead({ outcome: "skippedByBreaker", durationMs: 0 }); | |
| recordPageRead({ outcome: "notADocument", durationMs: 2 }); | |
| recordPageRead({ outcome: "httpForbidden", durationMs: 3 }); | |
| recordPageRead({ outcome: "httpNotFound", durationMs: 4 }); | |
| recordPageRead({ outcome: "httpOtherError", durationMs: 5 }); | |
| recordPageRead({ outcome: "redirectLimit", durationMs: 6 }); | |
| recordPageRead({ outcome: "timedOut", durationMs: 6000 }); | |
| recordPageRead({ outcome: "tooLittleText", durationMs: 7 }); | |
| recordPageRead({ outcome: "failed", durationMs: 8 }); | |
| }); | |
| expect(counted.requested).toBe(10); | |
| expect(counted.read).toBe(0); | |
| expect(counted.skipped).toEqual({ | |
| blocked: 1, | |
| skippedByBreaker: 1, | |
| notADocument: 1, | |
| httpForbidden: 1, | |
| httpNotFound: 1, | |
| httpOtherError: 1, | |
| redirectLimit: 1, | |
| timedOut: 1, | |
| tooLittleText: 1, | |
| failed: 1, | |
| }); | |
| }); | |
| it("keeps read plus the skipped reasons equal to requested", () => { | |
| const { after } = delta(() => | |
| recordPageRead({ outcome: "timedOut", durationMs: 6000 }), | |
| ); | |
| const accounted = | |
| after.read + | |
| Object.values(after.skipped).reduce((total, count) => total + count, 0); | |
| expect(accounted).toBe(after.requested); | |
| }); | |
| it("counts a truncated body only when it was truncated", () => { | |
| const counted = delta(() => { | |
| recordPageRead({ outcome: "read", durationMs: 10, bodyTruncated: true }); | |
| recordPageRead({ outcome: "read", durationMs: 10 }); | |
| }); | |
| expect(counted.read).toBe(2); | |
| expect(counted.bodiesTruncated).toBe(1); | |
| }); | |
| }); | |
| describe("getPageReadStats", () => { | |
| it("reports a rate and an average over everything requested", () => { | |
| const before = getPageReadStats(); | |
| recordPageRead({ outcome: "read", durationMs: 300 }); | |
| recordPageRead({ outcome: "timedOut", durationMs: 6000 }); | |
| const after = getPageReadStats(); | |
| expect(after.requested).toBe(before.requested + 2); | |
| expect(after.readRate).toBeGreaterThan(0); | |
| expect(after.readRate).toBeLessThanOrEqual(100); | |
| // A timeout is part of the cost of the feature, so it belongs in the mean. | |
| expect(after.averageReadMs).toBeGreaterThan(0); | |
| }); | |
| it("reports zeroes rather than NaN before anything has been read", async () => { | |
| // A fresh module instance is the only way to see the pre-first-read state, | |
| // where every derived number divides by zero. | |
| vi.resetModules(); | |
| const fresh = await import("./pageReadsSinceLastRestart"); | |
| expect(fresh.getPageReadStats()).toMatchObject({ | |
| requested: 0, | |
| read: 0, | |
| readRate: 0, | |
| averageReadMs: 0, | |
| excerptKeptRate: 0, | |
| }); | |
| }); | |
| it("reports how much of a page the budget kept, not how many overflowed", async () => { | |
| vi.resetModules(); | |
| const fresh = await import("./pageReadsSinceLastRestart"); | |
| // Both pages overflow, so a count of pages that overflowed would read 100% | |
| // here and say nothing about where the budget sits. | |
| fresh.recordPageRead({ | |
| outcome: "read", | |
| durationMs: 10, | |
| passagesKept: 5, | |
| passagesAvailable: 100, | |
| }); | |
| fresh.recordPageRead({ | |
| outcome: "read", | |
| durationMs: 10, | |
| passagesKept: 15, | |
| passagesAvailable: 100, | |
| }); | |
| expect(fresh.getPageReadStats().excerptKeptRate).toBe(10); | |
| }); | |
| it("reports the whole page kept when it all fit", async () => { | |
| vi.resetModules(); | |
| const fresh = await import("./pageReadsSinceLastRestart"); | |
| fresh.recordPageRead({ | |
| outcome: "read", | |
| durationMs: 10, | |
| passagesKept: 4, | |
| passagesAvailable: 4, | |
| }); | |
| expect(fresh.getPageReadStats().excerptKeptRate).toBe(100); | |
| }); | |
| }); | |