test: lift utility coverage above target

src/arrays.test.ts

@@ -0,0 +1,41 @@
+import { describe, expect, it } from "vitest";
+import { chunk, dedupe, groupBy } from "./arrays";
+
+describe("chunk", () => {
+  it("splits an array into fixed-size chunks", () => {
+    expect(chunk([1, 2, 3, 4, 5], 2)).toEqual([[1, 2], [3, 4], [5]]);
+  });
+
+  it("returns an empty array for non-positive sizes", () => {
+    expect(chunk([1, 2, 3], 0)).toEqual([]);
+    expect(chunk([1, 2, 3], -1)).toEqual([]);
+  });
+
+  it("returns no chunks for an empty input", () => {
+    expect(chunk([], 3)).toEqual([]);
+  });
+});
+
+describe("dedupe", () => {
+  it("keeps the first occurrence order", () => {
+    expect(dedupe(["a", "b", "a", "c", "b"])).toEqual(["a", "b", "c"]);
+  });
+
+  it("uses Set identity semantics for objects", () => {
+    const shared = { id: 1 };
+    const other = { id: 1 };
+    expect(dedupe([shared, other, shared])).toEqual([shared, other]);
+  });
+});
+
+describe("groupBy", () => {
+  it("groups values by string keys", () => {
+    const result = groupBy(["apple", "apricot", "banana"], (x) => x[0]);
+    expect(result).toEqual({ a: ["apple", "apricot"], b: ["banana"] });
+  });
+
+  it("groups values by numeric keys", () => {
+    const result = groupBy([1, 2, 3, 4], (x) => x % 2);
+    expect(result).toEqual({ 0: [2, 4], 1: [1, 3] });
+  });
+});

src/dates.test.ts

@@ -0,0 +1,44 @@
+import { describe, expect, it } from "vitest";
+import { addDays, daysBetween, isWeekend, startOfDayUTC } from "./dates";
+
+describe("daysBetween", () => {
+  it("returns the absolute day distance", () => {
+    const a = new Date("2026-05-01T00:00:00Z");
+    const b = new Date("2026-05-04T00:00:00Z");
+    expect(daysBetween(a, b)).toBe(3);
+    expect(daysBetween(b, a)).toBe(3);
+  });
+
+  it("rounds partial days to the nearest whole day", () => {
+    const a = new Date("2026-05-01T00:00:00Z");
+    const b = new Date("2026-05-02T13:00:00Z");
+    expect(daysBetween(a, b)).toBe(2);
+  });
+});
+
+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("adds positive and negative day offsets without mutating input", () => {
+    const input = new Date("2026-05-27T10:30:00Z");
+    expect(addDays(input, 2).toISOString()).toBe("2026-05-29T10:30:00.000Z");
+    expect(addDays(input, -3).toISOString()).toBe("2026-05-24T10:30:00.000Z");
+    expect(input.toISOString()).toBe("2026-05-27T10:30:00.000Z");
+  });
+});
+
+describe("startOfDayUTC", () => {
+  it("returns midnight UTC for the supplied date", () => {
+    const result = startOfDayUTC(new Date("2026-05-27T23:59:59Z"));
+    expect(result.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 symbols", () => {
+    expect(formatCents(12345)).toBe("$123.45");
+    expect(formatCents(12345, "EUR")).toBe("€123.45");
+  });
+
+  it("falls back to the currency code for other currencies", () => {
+    expect(formatCents(987, "GBP")).toBe("GBP 9.87");
+  });
+});
+
+describe("platformFeeCents", () => {
+  it("rounds basis-point fees to whole cents", () => {
+    expect(platformFeeCents(999, 250)).toBe(25);
+  });
+
+  it("returns zero for non-positive gross amounts or rates", () => {
+    expect(platformFeeCents(0, 250)).toBe(0);
+    expect(platformFeeCents(1000, 0)).toBe(0);
+  });
+});
+
+describe("netPayoutCents", () => {
+  it("subtracts the platform fee from the gross amount", () => {
+    expect(netPayoutCents(10_000, 250)).toBe(9_750);
+  });
+});
+
+describe("splitEvenly", () => {
+  it("splits cents evenly and distributes the remainder first", () => {
+    expect(splitEvenly(10, 3)).toEqual([4, 3, 3]);
+  });
+
+  it("returns an empty split for non-positive participant counts", () => {
+    expect(splitEvenly(10, 0)).toEqual([]);
+    expect(splitEvenly(10, -2)).toEqual([]);
+  });
+});

src/strings.test.ts

@@ -1,7 +1,48 @@
-import { describe, it, expect } from "vitest";
-import { slugify } from "./strings";
+import { describe, expect, it } from "vitest";
+import { escapeHtml, slugify, titleCase, truncate } from "./strings";
+
 describe("slugify", () => {
-  it("lowercases and dashifies basic input", () => {
-    expect(slugify("Hello World")).toBe("hello-world");
+  it("lowercases, trims, and dashifies basic input", () => {
+    expect(slugify("  Hello World  ")).toBe("hello-world");
+  });
+
+  it("removes punctuation and collapses repeated separators", () => {
+    expect(slugify("Ship fast!!!  With---tests")).toBe("ship-fast-with-tests");
+  });
+});
+
+describe("truncate", () => {
+  it("returns short strings unchanged", () => {
+    expect(truncate("short", 10)).toBe("short");
+  });
+
+  it("adds a suffix when the input exceeds max length", () => {
+    expect(truncate("abcdefgh", 6, "...")).toBe("abc...");
+  });
+
+  it("handles non-positive max lengths", () => {
+    expect(truncate("abcdefgh", 0)).toBe("");
+  });
+
+  it("does not slice below zero when suffix is longer than max", () => {
+    expect(truncate("abcdefgh", 2, "...")).toBe("...");
+  });
+});
+
+describe("titleCase", () => {
+  it("capitalizes words and normalizes casing", () => {
+    expect(titleCase("hello WORLD from TESTS")).toBe("Hello World From Tests");
+  });
+
+  it("preserves spacing behavior from split and join", () => {
+    expect(titleCase("  hello   world  ")).toBe(" Hello World ");
+  });
+});
+
+describe("escapeHtml", () => {
+  it("escapes all supported HTML-sensitive characters", () => {
+    expect(escapeHtml(`Tom & "Jerry" <cat>'s tail>`)).toBe(
+      "Tom &amp; &quot;Jerry&quot; &lt;cat&gt;&#39;s tail&gt;",
+    );
   });
 });