mockWindow()

mockWindow(overrides): MockWindowResult

Creates a mock window object on globalThis for Node.js tests.

remarque

Always call restore() for cleanup. Auto-restored after each test if forgotten.

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Parameters

overrides: Partial<Window> = {}

Properties to set on the mock window.

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Returns: MockWindowResult

Object containing the mock window and restore function.

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Since

2.0.0

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Example

const { window, restore } = mockWindow({ innerWidth: 1024 });
expect(window.innerWidth).toBe(1024);
restore();

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Use Cases

Mock window properties 📌

Safely override window properties for Node.js-based tests. Essential for testing responsive design logic or window event handlers.

#mock#window#properties#testing#responsive#viewport

const { restore } = mockWindow({
  innerWidth: 768,
  innerHeight: 1024
});

expect(isMobile()).toBe(true);
restore();

Simulate different viewports

Test responsive breakpoints and layout changes.

#simulate#viewports#responsive#breakpoints#layout#testing

const { restore } = mockWindow({ innerWidth: 1920 });
expect(getBreakpoint()).toBe('desktop');
restore();

const { restore: restore2 } = mockWindow({ innerWidth: 375 });
expect(getBreakpoint()).toBe('mobile');
restore2();

Mock storage APIs

Test localStorage/sessionStorage interactions.

#mock#storage#localStorage#sessionStorage#testing#persistence

const storage = new Map();
const { restore } = mockWindow({
  localStorage: {
    getItem: (k) => storage.get(k),
    setItem: (k, v) => storage.set(k, v)
  }
});

savePreference('theme', 'dark');
expect(storage.get('theme')).toBe('dark');
restore();

MockWindowResult

Interface

Result of mockWindow().

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Since

2.0.0

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Properties

window: any

restore(): () => void

Returns

void