Initial Commit

packages/localization/i18n/react-i18n/src/detector/html-lang/html-lang.test.ts

@@ -0,0 +1,117 @@
+import type { DetectorContext } from "@suaveplan/i18n-detector";
+import { describe, expect, it } from "@suaveplan/testing/runner";
+import { htmlLangDetector } from "./html-lang.js";
+
+const SUPPORTED = ["en-GB", "fr-FR", "de-DE"] as const;
+
+function browserContext(): DetectorContext {
+    return {
+        supportedLocales: SUPPORTED,
+        fallbackLocale: "en-GB",
+    };
+}
+
+function withDocumentLang<T>(lang: unknown, fn: () => T): T {
+    const original = (globalThis as { document?: unknown }).document;
+    Object.defineProperty(globalThis, "document", {
+        configurable: true,
+        value: { documentElement: { lang } },
+    });
+    try {
+        return fn();
+    } finally {
+        Object.defineProperty(globalThis, "document", {
+            configurable: true,
+            value: original,
+        });
+    }
+}
+
+describe("htmlLangDetector", () => {
+    it("exposes name and environment per spec", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        expect(detector.name).toBe("htmlLang");
+        expect(detector.environment).toBe("browser");
+    });
+
+    it("reads document.documentElement.lang", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        withDocumentLang("fr-FR", () => {
+            expect(detector.detect?.(browserContext())).toBe("fr-FR");
+        });
+    });
+
+    it("trims surrounding whitespace", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        withDocumentLang("  de-DE  ", () => {
+            expect(detector.detect?.(browserContext())).toBe("de-DE");
+        });
+    });
+
+    it("returns null for empty lang attribute", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        withDocumentLang("", () => {
+            expect(detector.detect?.(browserContext())).toBeNull();
+        });
+    });
+
+    it("returns null when documentElement is missing", {
+        timeout: 5000,
+    }, () => {
+        const detector = htmlLangDetector();
+        const original = (globalThis as { document?: unknown }).document;
+        Object.defineProperty(globalThis, "document", {
+            configurable: true,
+            value: { documentElement: null },
+        });
+        try {
+            expect(detector.detect?.(browserContext())).toBeNull();
+        } finally {
+            Object.defineProperty(globalThis, "document", {
+                configurable: true,
+                value: original,
+            });
+        }
+    });
+
+    it("returns null when lang is not a string", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        withDocumentLang(12345, () => {
+            expect(detector.detect?.(browserContext())).toBeNull();
+        });
+    });
+
+    it("returns null when no document is available", { timeout: 5000 }, () => {
+        const detector = htmlLangDetector();
+        const original = (globalThis as { document?: unknown }).document;
+        Object.defineProperty(globalThis, "document", {
+            configurable: true,
+            value: undefined,
+        });
+        try {
+            expect(detector.detect?.(browserContext())).toBeNull();
+        } finally {
+            Object.defineProperty(globalThis, "document", {
+                configurable: true,
+                value: original,
+            });
+        }
+    });
+
+    it("uses ctx.document over globalThis.document when supplied", {
+        timeout: 5000,
+    }, () => {
+        const detector = htmlLangDetector();
+        withDocumentLang("en-GB", () => {
+            const injected = {
+                documentElement: { lang: "fr-FR" },
+            } as unknown as Document;
+            expect(
+                detector.detect?.({
+                    ...browserContext(),
+                    document: injected,
+                })
+            ).toBe("fr-FR");
+        });
+    });
+});