import { afterEach, describe, expect, it } from "vitest"; import { detectPageLanguage } from "./detectPageLanguage"; function setBrowserLanguage(value: string | undefined) { Object.defineProperty(navigator, "language", { value, configurable: true, }); } function setHtmlLang(value: string) { document.documentElement.lang = value; } describe.sequential("detectPageLanguage", () => { afterEach(() => { setBrowserLanguage("en-US"); setHtmlLang(""); }); it("prefers the page over the browser language", () => { setBrowserLanguage("en-US"); setHtmlLang("fr-FR"); expect(detectPageLanguage()).toBe("fr"); }); it("falls back to the browser language when is unset", () => { setHtmlLang(""); setBrowserLanguage("fr-FR"); expect(detectPageLanguage()).toBe("fr"); }); it("returns undefined for unsupported languages", () => { setHtmlLang("de"); setBrowserLanguage("de-DE"); expect(detectPageLanguage()).toBeUndefined(); }); it("ignores an unsupported and uses the browser language", () => { setHtmlLang("de-DE"); setBrowserLanguage("fr-FR"); expect(detectPageLanguage()).toBe("fr"); }); });