Stability fixes: plugin-scoped contexts for owned pages, absent-href guard, checked locale mounts

src/i18n/view-locals.test.ts

@@ -0,0 +1,32 @@
+import assert from "node:assert/strict";
+import { test } from "node:test";
+import { ENGLISH } from "./english.ts";
+import { localeHref } from "./locale.ts";
+import { i18nLocals, type I18nRequest } from "./view-locals.ts";
+
+const request = (overrides: Partial<I18nRequest> = {}): I18nRequest => ({
+  locale: "sv-SE",
+  localeHref: (href) => href,
+  locales: ["en-US", "sv-SE"],
+  t: ENGLISH,
+  url: new URL("http://localhost/admin/users?q=ada"),
+  ...overrides,
+});
+
+test("localeSwitch offers this same page in every installed locale, marking the current one", () => {
+  const locals = i18nLocals(request());
+  assert.deepEqual(locals.localeSwitch.map((c) => c.href), ["/admin/users?q=ada&locale=en-US", "/admin/users?q=ada&locale=sv-SE"]);
+  assert.deepEqual(locals.localeSwitch.map((c) => c.current), [false, true]);
+  assert.match(locals.localeSwitch[1]?.label ?? "", /svenska/i); // named in its own language
+});
+
+test("localeParam is the tag only when the URL asked — it is what the GET forms carry", () => {
+  // The probe asks the very function that decides, so the two can't drift apart.
+  assert.equal(i18nLocals(request()).localeParam, null); // identity localeHref ⇒ nothing was chosen
+  assert.equal(i18nLocals(request({ localeHref: (href) => localeHref(href, "sv-SE") })).localeParam, "sv-SE");
+});
+
+test("dir follows the locale's script", () => {
+  assert.equal(i18nLocals(request()).dir, "ltr");
+  assert.equal(i18nLocals(request({ locale: "ar-EG" })).dir, "rtl");
+});