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Jest · Module

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Jest mock functions replace or observe functions during tests. Create one with jest.fn(), configure its behavior, and inspect its calls.

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Syntax

jest.fn(implementation?)

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  • jest.fn()
  • mockFn.mock.calls
  • mockFn.mock.results
  • mockFn.mockClear()
  • mockFn.mockImplementation()
  • jest.Mocked<Source>

Source: Mock Functions · Jest. Checked 2026-11-03.