block15.js

// ...
import NestedRoute from "@/compoents/NestedRoute.vue"
import mockModule from "@/bust-cache.js"

jest.mock("@/bust-cache.js", () => ({ bustCache: jest.fn() }))

it("calls bustCache and next when leaving the route", () => {
  const next = jest.fn()
  NestedRoute.beforeRouteLeave(undefined, undefined, next)

  expect(mockModule.bustCache).toHaveBeenCalled()
  expect(next).toHaveBeenCalled()
})