nostr-fetch/src/fetcherHelper.spec.ts

A utility library that allows JS/TS apps to effortlessly fetch past events from Nostr relays

import type { NostrEvent } from "@nostr-fetch/kernel/nostr";
import { describe, expect, test } from "vitest";
import { EventBuckets, KeyRelayMatrix, compareNostrEvents, initSeenEvents } from "./fetcherHelper";

const dummyEventWithCreatedAtAndId = (created_at: number, id: string): NostrEvent => ({
  id,
  pubkey: "",
  kind: 0,
  content: "",
  tags: [],
  created_at,
  sig: "",
});

describe("compareNostrEvents", () => {
  test("compares Nostr events correctly", () => {
    const older = dummyEventWithCreatedAtAndId(100, "0");
    const newer1 = dummyEventWithCreatedAtAndId(200, "1");
    const newer2 = dummyEventWithCreatedAtAndId(200, "2");

    // newer event comes first
    expect(compareNostrEvents(newer1, older)).toBeLessThan(0);
    expect(compareNostrEvents(newer2, older)).toBeLessThan(0);
    expect(compareNostrEvents(older, newer1)).toBeGreaterThan(0);
    expect(compareNostrEvents(older, newer2)).toBeGreaterThan(0);

    // event with lower id comes first if they have the same created_at
    expect(compareNostrEvents(newer1, newer2)).toBeLessThan(0);
    expect(compareNostrEvents(newer2, newer1)).toBeGreaterThan(0);

    // returns 0 if the events are the same
    expect(compareNostrEvents(older, older)).toBe(0);
    expect(compareNostrEvents(newer1, newer1)).toBe(0);
    expect(compareNostrEvents(newer2, newer2)).toBe(0);
  });
});

const dummyEventWithId = (id: string) => {
  return {
    id,
    pubkey: "",
    kind: 0,
    content: "",
    tags: [],
    created_at: 0,
    sig: "",
  };
};

describe("EventBuckets", () => {
  test("has buckets for all keys specified on initialization", () => {
    const buckets = new EventBuckets(["alice", "bob"], 10);

    expect(buckets.getBucket("alice")).toBeDefined();
    expect(buckets.getBucket("bob")).toBeDefined();
    expect(buckets.getBucket("unknown")).toBeUndefined();
  });

  test("add() works correctly", () => {
    const e1 = dummyEventWithId("1");
    const e2 = dummyEventWithId("2");

    const buckets = new EventBuckets(["alice", "bob"], 2);

    expect(buckets.add("alice", e1).state).toBe("open");
    expect(buckets.add("alice", e2)).toEqual({
      state: "fulfilled",
      events: expect.arrayContaining([e1, e2]),
    });
    expect(buckets.add("alice", e1).state).toBe("dropped");

    buckets.add("bob", e1);
    expect(buckets.add("bob", e2)).toEqual({
      state: "fulfilled",
      events: expect.arrayContaining([e1, e2]),
    });

    expect(buckets.add("unknown", e1).state).toBe("dropped");
  });

  test("calcKeyAndLimitForNextReq() works correctly", () => {
    const e = dummyEventWithId("1");

    const buckets = new EventBuckets(["alice", "bob"], 2);
    expect(buckets.calcKeysAndLimitForNextReq()).toEqual({
      keys: expect.arrayContaining(["alice", "bob"]),
      limit: 4,
    });

    buckets.add("alice", e);
    expect(buckets.calcKeysAndLimitForNextReq()).toEqual({
      keys: expect.arrayContaining(["alice", "bob"]),
      limit: 3,
    });

    buckets.add("bob", e);
    expect(buckets.calcKeysAndLimitForNextReq()).toEqual({
      keys: expect.arrayContaining(["alice", "bob"]),
      limit: 2,
    });

    buckets.add("bob", e);
    expect(buckets.calcKeysAndLimitForNextReq()).toEqual({
      keys: ["alice"],
      limit: 1,
    });

    buckets.add("alice", e);
    expect(buckets.calcKeysAndLimitForNextReq()).toEqual({
      keys: [],
      limit: 0,
    });
  });
});

describe("KeyRelayMatrix", () => {
  test("has expected entries", () => {
    const matrix = new KeyRelayMatrix(
      new Map([
        ["relay1", [1, 2, 3]],
        ["relay2", [2, 3]],
        ["relay3", [3]],
      ]),
      () => 0,
    );

    expect(matrix.get(1, "relay1")).toBeDefined();
    expect(matrix.get(2, "relay1")).toBeDefined();
    expect(matrix.get(3, "relay1")).toBeDefined();
    expect(matrix.get(2, "relay2")).toBeDefined();
    expect(matrix.get(3, "relay2")).toBeDefined();
    expect(matrix.get(3, "relay3")).toBeDefined();

    expect(matrix.get(1, "relay2")).toBeUndefined();
    expect(matrix.get(1, "relay3")).toBeUndefined();
    expect(matrix.get(2, "relay3")).toBeUndefined();

    expect(matrix.itemsByKey(1)?.length ?? -1).toBe(1);
    expect(matrix.itemsByKey(2)?.length ?? -1).toBe(2);
    expect(matrix.itemsByKey(3)?.length ?? -1).toBe(3);
  });
});

describe("SeenEvents", () => {
  test("SeenOnTable (withSeenOn = true) works", () => {
    const seenEvents = initSeenEvents(true);

    const res1 = seenEvents.report(dummyEventWithId("1"), "relay1");
    expect(res1.hasSeen).toBe(false);
    expect(res1.seenOn).toEqual(["relay1"]);

    const res2 = seenEvents.report(dummyEventWithId("2"), "relay2");
    expect(res2.hasSeen).toBe(false);
    expect(res2.seenOn).toEqual(["relay2"]);

    const res3 = seenEvents.report(dummyEventWithId("1"), "relay2");
    expect(res3.hasSeen).toBe(true);
    expect(res3.seenOn).toEqual(["relay1", "relay2"]);

    expect(seenEvents.getSeenOn("1")).toEqual(["relay1", "relay2"]);
    expect(seenEvents.getSeenOn("2")).toEqual(["relay2"]);
    expect(seenEvents.getSeenOn("3")).toEqual([]);
  });

  test("SeenEventsSet (withSeenOn = false) works", () => {
    const seenEvents = initSeenEvents(false);

    const res1 = seenEvents.report(dummyEventWithId("1"), "relay1");
    expect(res1.hasSeen).toBe(false);
    expect(res1.seenOn).toBeUndefined();

    const res2 = seenEvents.report(dummyEventWithId("2"), "relay2");
    expect(res2.hasSeen).toBe(false);

    const res3 = seenEvents.report(dummyEventWithId("1"), "relay2");
    expect(res3.hasSeen).toBe(true);
  });
});