Add coverage tests for tiny utils

src/arrays.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, it } from "vitest";
+import { chunk, dedupe, groupBy } from "./arrays";
+
+describe("chunk", () => {
+  it("splits arrays into fixed-size groups", () => {
+    expect(chunk([1, 2, 3, 4, 5], 2)).toEqual([[1, 2], [3, 4], [5]]);
+  });
+
+  it("returns an empty array for invalid chunk sizes", () => {
+    expect(chunk([1, 2, 3], 0)).toEqual([]);
+    expect(chunk([1, 2, 3], -1)).toEqual([]);
+  });
+});
+
+describe("dedupe", () => {
+  it("keeps first occurrences in insertion order", () => {
+    expect(dedupe(["a", "b", "a", "c", "b"])).toEqual(["a", "b", "c"]);
+  });
+});
+
+describe("groupBy", () => {
+  it("groups items by the selected key", () => {
+    const rows = [
+      { kind: "fruit", name: "apple" },
+      { kind: "veg", name: "carrot" },
+      { kind: "fruit", name: "pear" },
+    ];
+
+    expect(groupBy(rows, (row) => row.kind)).toEqual({
+      fruit: [rows[0], rows[2]],
+      veg: [rows[1]],
+    });
+  });
+});

src/dates.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from "vitest";
+import { addDays, daysBetween, isWeekend, startOfDayUTC } from "./dates";
+
+describe("daysBetween", () => {
+  it("returns rounded absolute day difference", () => {
+    const a = new Date("2026-05-27T00:00:00Z");
+    const b = new Date("2026-05-29T13:00:00Z");
+
+    expect(daysBetween(a, b)).toBe(3);
+    expect(daysBetween(b, a)).toBe(3);
+  });
+});
+
+describe("isWeekend", () => {
+  it("detects Saturday and Sunday", () => {
+    expect(isWeekend(new Date("2026-05-30T12:00:00Z"))).toBe(true);
+    expect(isWeekend(new Date("2026-05-31T12:00:00Z"))).toBe(true);
+  });
+
+  it("returns false for weekdays", () => {
+    expect(isWeekend(new Date("2026-05-27T12:00:00Z"))).toBe(false);
+  });
+});
+
+describe("addDays", () => {
+  it("returns a new date offset by the requested day count", () => {
+    const original = new Date("2026-05-27T08:30:00Z");
+    const result = addDays(original, 5);
+
+    expect(result.toISOString()).toBe("2026-06-01T08:30:00.000Z");
+    expect(original.toISOString()).toBe("2026-05-27T08:30:00.000Z");
+  });
+});
+
+describe("startOfDayUTC", () => {
+  it("normalizes to midnight UTC", () => {
+    expect(startOfDayUTC(new Date("2026-05-27T23:59:30Z")).toISOString()).toBe("2026-05-27T00:00:00.000Z");
+  });
+});

src/money.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vitest";
+import { formatCents, netPayoutCents, platformFeeCents, splitEvenly } from "./money";
+
+describe("formatCents", () => {
+  it("formats USD and EUR with currency symbols", () => {
+    expect(formatCents(1234)).toBe("$12.34");
+    expect(formatCents(1234, "EUR")).toBe("€12.34");
+  });
+
+  it("prefixes unknown currency codes", () => {
+    expect(formatCents(500, "GBP")).toBe("GBP 5.00");
+  });
+});
+
+describe("platformFeeCents", () => {
+  it("rounds basis point fees", () => {
+    expect(platformFeeCents(999, 250)).toBe(25);
+  });
+
+  it("returns zero for non-positive gross or bps", () => {
+    expect(platformFeeCents(0, 250)).toBe(0);
+    expect(platformFeeCents(1000, 0)).toBe(0);
+  });
+});
+
+describe("netPayoutCents", () => {
+  it("subtracts platform fee from the gross amount", () => {
+    expect(netPayoutCents(1000, 2000)).toBe(800);
+  });
+});
+
+describe("splitEvenly", () => {
+  it("splits remainder cents across the earliest recipients", () => {
+    expect(splitEvenly(10, 3)).toEqual([4, 3, 3]);
+  });
+
+  it("returns an empty list for non-positive recipient counts", () => {
+    expect(splitEvenly(10, 0)).toEqual([]);
+    expect(splitEvenly(10, -2)).toEqual([]);
+  });
+});

src/strings.test.ts

@@ -1,7 +1,43 @@
 import { describe, it, expect } from "vitest";
-import { slugify } from "./strings";
+import { escapeHtml, slugify, titleCase, truncate } from "./strings";
+
 describe("slugify", () => {
   it("lowercases and dashifies basic input", () => {
     expect(slugify("Hello World")).toBe("hello-world");
   });
+
+  it("removes punctuation and collapses repeated dashes", () => {
+    expect(slugify("  Hello,   Tiny---Utils!  ")).toBe("hello-tiny-utils");
+  });
+});
+
+describe("truncate", () => {
+  it("returns an empty string for non-positive max length", () => {
+    expect(truncate("hello", 0)).toBe("");
+    expect(truncate("hello", -3)).toBe("");
+  });
+
+  it("keeps short input unchanged", () => {
+    expect(truncate("short", 10)).toBe("short");
+  });
+
+  it("uses the suffix within the max length", () => {
+    expect(truncate("abcdef", 5, "...")).toBe("ab...");
+  });
+});
+
+describe("titleCase", () => {
+  it("capitalizes each whitespace-separated word", () => {
+    expect(titleCase("hello WORLD tiny")).toBe("Hello World Tiny");
+  });
+
+  it("preserves empty segments when input has leading whitespace", () => {
+    expect(titleCase("  mixed")).toBe(" Mixed");
+  });
+});
+
+describe("escapeHtml", () => {
+  it("escapes common HTML-sensitive characters", () => {
+    expect(escapeHtml(`Tom & "Sue" <tag>'`)).toBe("Tom &amp; &quot;Sue&quot; &lt;tag&gt;&#39;");
+  });
 });