Add vitest and unit coverage for provider helpers

src/index.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it } from "vitest";
+import { normalizeE164, toWhatsappJid, assertProvider } from "./index.js";
+
+describe("normalizeE164", () => {
+	it("strips whatsapp: prefix and whitespace", () => {
+		expect(normalizeE164("whatsapp:+1 555 123 4567")).toBe("+15551234567");
+	});
+
+	it("adds plus when missing", () => {
+		expect(normalizeE164("1555123")).toBe("+1555123");
+	});
+});
+
+describe("toWhatsappJid", () => {
+	it("converts E164 to jid", () => {
+		expect(toWhatsappJid("+1 555 123 4567")).toBe("15551234567@s.whatsapp.net");
+	});
+});
+
+describe("assertProvider", () => {
+	it("accepts valid providers", () => {
+		expect(() => assertProvider("twilio")).not.toThrow();
+		expect(() => assertProvider("web")).not.toThrow();
+	});
+
+	it("throws on invalid provider", () => {
+		expect(() => assertProvider("invalid" as string)).toThrow();
+	});
+});