João Salavisa
45 lines
1.8 KiB
TypeScript
45 lines
1.8 KiB
TypeScript
import { describe, expect, it, vi } from "vitest";
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/**
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* `I18nProvider` must initialize the shared instance as a side effect of being
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* imported, because nothing else in the boot path does.
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*
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* react-i18next suspends when `useTranslation()` runs against an uninitialized
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* instance. There is no Suspense boundary above the React root, so a suspended
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* first render never commits: the app shows a blank page with no console error,
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* no page error and no unhandled rejection — every asset returns 200 and
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* `#root` is simply empty. It is a genuinely silent failure.
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*
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* Initialization used to happen by accident. `activateLocale()` only runs from
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* the language switcher, so at boot the instance was set up purely because some
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* module called the module-level `t()` while evaluating — `t()` calls
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* `ensureInitialized`. Removing the last such call (a module-scope config
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* constant) blanked the whole app and every e2e test failed on an empty page.
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* See docs/i18n.md ("How it's wired").
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*
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* NOTE: this cannot be asserted by rendering. `vitest.setup.ts` calls
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* `initI18nForTests()` for every suite, so `i18n.isInitialized` is already true
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* and any render-based check would pass even with the boot call deleted. The
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* import side effect itself is therefore what gets verified here.
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*/
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describe("I18nProvider boot contract", () => {
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it("initializes the shared instance when the module is imported", async () => {
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vi.resetModules();
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const initI18n = vi.fn();
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vi.doMock("./index", async () => ({
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...(await vi.importActual<typeof import("./index")>("./index")),
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initI18n,
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}));
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await import("./provider");
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expect(
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initI18n,
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"provider.tsx must call initI18n() at module scope — without it the app " +
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"renders a blank page with no error",
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).toHaveBeenCalledTimes(1);
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vi.doUnmock("./index");
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});
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});
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