test: add unit tests for parseId helper

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/lib/params.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, it } from "bun:test";
+import { parseId } from "../../src/server/lib/params";
+
+describe("parseId", () => {
+	it("returns number for valid positive integers", () => {
+		expect(parseId("1")).toBe(1);
+		expect(parseId("42")).toBe(42);
+		expect(parseId("999")).toBe(999);
+	});
+
+	it("returns null for zero", () => {
+		expect(parseId("0")).toBeNull();
+	});
+
+	it("returns null for negative numbers", () => {
+		expect(parseId("-1")).toBeNull();
+		expect(parseId("-100")).toBeNull();
+	});
+
+	it("returns null for decimals", () => {
+		expect(parseId("1.5")).toBeNull();
+		expect(parseId("3.14")).toBeNull();
+	});
+
+	it("returns null for non-numeric strings", () => {
+		expect(parseId("abc")).toBeNull();
+		expect(parseId("")).toBeNull();
+		expect(parseId("hello")).toBeNull();
+		expect(parseId("12abc")).toBeNull();
+	});
+
+	it("returns null for special values", () => {
+		expect(parseId("NaN")).toBeNull();
+		expect(parseId("Infinity")).toBeNull();
+		expect(parseId("-Infinity")).toBeNull();
+	});
+});