Function createMock

packages/spy/src/index.ts:429–575

(
  {
    state,
    config,
    name: mockName,
    prototypeState,
    prototypeConfig,
    keepMembersImplementation,
    mockImplementation,
    prototypeMembers = [],
  }: MockInstanceOption & {
    state: MockContext
    config: MockConfig
  },
)

let invocationCallCounter = 1

function createMock(
  {
    state,
    config,
    name: mockName,
    prototypeState,
    prototypeConfig,
    keepMembersImplementation,
    mockImplementation,
    prototypeMembers = [],
  }: MockInstanceOption & {
    state: MockContext
    config: MockConfig
  },
) {
  const original = config.mockOriginal // init with vi.spyOn(obj, 'Klass')
  const pseudoOriginal = mockImplementation // init with vi.fn(Klass)
  const name = (mockName || original?.name || 'Mock') as string
  const namedObject: Record<string, Mock<Procedure | Constructable>> = {
    // to keep the name of the function intact
    [name]: (function (this: any, ...args: any[]) {
      registerCalls(args, state, prototypeState)
      registerInvocationOrder(invocationCallCounter++, state, prototypeState)

      const result = {
        type: 'incomplete',
        value: undefined,
      } as MockResult<Procedure>

      const settledResult = {
        type: 'incomplete',
        value: undefined,
      } as MockSettledResult<Procedure>

      registerResult(result, state, prototypeState)
      registerSettledResult(settledResult, state, prototypeState)

      const context = new.target ? undefined : this
      const [instanceIndex, instancePrototypeIndex] = registerInstance(context, state, prototypeState)
      const [contextIndex, contextPrototypeIndex] = registerContext(context, state, prototypeState)

      const implementation: Procedure | Constructable
        = config.onceMockImplementations.shift()
          || config.mockImplementation
          || prototypeConfig?.onceMockImplementations.shift()
          || prototypeConfig?.mockImplementation
          || original
          || function () {}

      let returnValue
      let thrownValue
      let didThrow = false

      try {
        if (new.target) {
          returnValue = Reflect.construct(implementation, args, new.target)

          // jest calls this before the implementation, but we have to resolve this _after_