Function fn

packages/spy/src/index.ts:244–260

(
  originalImplementation?: T,
)

}

export function fn<T extends Procedure | Constructable = Procedure>(
  originalImplementation?: T,
): Mock<T> {
  // if the function is already a mock, just return the same function,
  // similarly to how vi.spyOn() works
  if (originalImplementation != null && isMockFunction(originalImplementation)) {
    return originalImplementation as Mock<T>
  }

  return createMockInstance({
    // we pass this down so getMockImplementation() always returns the value
    mockImplementation: originalImplementation,
    // special case so that .mockReset() resets the value to
    // the the originalImplementation instead of () => undefined
    resetToMockImplementation: true,
  }) as Mock<T>
}

export function spyOn<T extends object, S extends Properties<Required<T>>>(
  object: T,