update

tests/app/utils/helper.test.ts

@@ -0,0 +1,42 @@
+import { describe, it, expect } from "vitest";
+import { makeFirstCharUpper, formatDate, getRandomFallbackImage } from "../../../app/utils/helper";
+
+describe("helper utilities", () => {
+  it("makeFirstCharUpper should uppercase first char", () => {
+    expect(makeFirstCharUpper("")).toBe("");
+    expect(makeFirstCharUpper("hello")).toBe("Hello");
+    expect(makeFirstCharUpper("Hello")).toBe("Hello");
+  });
+
+  it("formatDate should format ISO strings to YYYY-MM-DD or return empty for invalid", () => {
+    expect(formatDate("")).toBe("");
+    expect(formatDate("not-a-date")).toBe("");
+    expect(formatDate("2020-03-05T12:00:00Z")).toBe("2020-03-05");
+    expect(formatDate("2021-12-31")).toBe("2021-12-31");
+  });
+
+  it("getRandomFallbackImage should be deterministic with seed and stable without seed", () => {
+    const firstNoSeed = getRandomFallbackImage();
+    expect(firstNoSeed).toBe("/404/1.webp");
+
+    const a = getRandomFallbackImage("seed-123");
+    const b = getRandomFallbackImage("seed-123");
+    expect(a).toBe(b);
+
+    const c = getRandomFallbackImage("other-seed");
+    // different seed likely different index, but at least ensure value is from list
+    const allowed = [
+      "/404/1.webp",
+      "/404/2.webp",
+      "/404/3.webp",
+      "/404/4.webp",
+      "/404/5.webp",
+      "/404/6.webp",
+      "/404/7.webp",
+      "/404/8.webp",
+      "/404/9.webp",
+    ];
+    expect(allowed).toContain(a);
+    expect(allowed).toContain(c);
+  });
+});