chore: import upstream snapshot with attribution

2026-07-13 13:32:57 +08:00
commit cd420f9332
4811 changed files with 884702 additions and 0 deletions
@@ -0,0 +1,46 @@
+import { describe, it, expect } from "vitest";
+import cuid from "cuid";
+import { hashBucket } from "~/utils/computeBucket";
+
+describe("hashBucket", () => {
+  it("returns a stable value in [0, 100) for the same id", () => {
+    const a = hashBucket("org_abc");
+    const b = hashBucket("org_abc");
+    expect(a).toBe(b);
+    expect(a).toBeGreaterThanOrEqual(0);
+    expect(a).toBeLessThan(100);
+  });
+
+  it("is nested: the set enrolled at 1% is a subset of the set at 5%", () => {
+    const ids = Array.from({ length: 5000 }, (_, i) => `org_${i}`);
+    const at1 = new Set(ids.filter((id) => hashBucket(id) < 1));
+    const at5 = ids.filter((id) => hashBucket(id) < 5);
+    for (const id of at1) {
+      expect(at5).toContain(id);
+    }
+  });
+
+  it("distributes roughly uniformly", () => {
+    const ids = Array.from({ length: 10000 }, (_, i) => `org_${i}`);
+    const under10 = ids.filter((id) => hashBucket(id) < 10).length;
+    expect(under10).toBeGreaterThan(700);
+    expect(under10).toBeLessThan(1300);
+  });
+
+  // Org ids are `@default(cuid())` primary keys (e.g. "cjld2cjxh0000qzrmn831i7rn"),
+  // not the synthetic sequential ids above. cuids share a "c" prefix + timestamp/counter
+  // structure, so verify the hash still spreads *real-shaped* ids evenly across deciles
+  // (so a percentage dial maps to ~that fraction of actual orgs, not just of the id space).
+  it("distributes cuids evenly across all 10 deciles", () => {
+    const ids = Array.from({ length: 20000 }, () => cuid());
+    const counts = new Array(10).fill(0);
+    for (const id of ids) {
+      counts[Math.floor(hashBucket(id) / 10)]++;
+    }
+    // Expected ~2000 per decile; allow a wide band so it isn't flaky.
+    for (const count of counts) {
+      expect(count).toBeGreaterThan(1700);
+      expect(count).toBeLessThan(2300);
+    }
+  });
+});