setGlobal()

setGlobal<T>(key, value): () => void

Sets a value on globalThis and returns a restore function.

note

Always call the returned restore function. Auto-restored after each test if forgotten.

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Type Parameters

T: T

The value type.

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Parameters

key: string

The key to set on globalThis.

value: T

The value to set.

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Returns

A restore function.

(): void

Returns: void

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Since

2.0.0

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Example

const restore = setGlobal('fetch', vi.fn());
// ... tests ...
restore();

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Use Cases

Inject global mocks 📌

Temporarily set a global variable (like fetch or IntersectionObserver). Useful for mocking browser APIs in a test environment.

#inject#global#mocks#testing#APIs#polyfill

const restore = setGlobal('fetch', vi.fn(() => 
  Promise.resolve({ ok: true, json: () => ({}) })
));

await fetchData('/api/users');
expect(globalThis.fetch).toHaveBeenCalled();
restore();

Mock missing APIs

Polyfill APIs that don't exist in Node.js test environment.

#mock#missing#APIs#polyfill#Node#testing

const restore = setGlobal('IntersectionObserver', MockIntersectionObserver);

const component = mount(<LazyImage />);
expect(component).toBeDefined();
restore();