ts-essentials#UnreachableCaseError TypeScript Examples

The following examples show how to use ts-essentials#UnreachableCaseError. You can vote up the ones you like or vote down the ones you don't like, and go to the original project or source file by following the links above each example. You may check out the related API usage on the sidebar.
Example #1
Source File: mockFn.ts From earl with MIT License
4 votes
export function mockFn<Args extends any[], Return = any>(defaultImpl?: (...args: Args) => Return): Mock<Args, Return> {
  let spec: Spec = {
    type: 'not-ready',
  }
  let queue: Spec[] = []
  let oneTimeOverrides: Override[] = []

  function mock(...args: any[]) {
    for (const override of oneTimeOverrides) {
      if (isEqual(args, override.args)) {
        oneTimeOverrides.splice(oneTimeOverrides.indexOf(override), 1)
        return runSpec(override.spec, args)
      }
    }
    const current = queue.shift() || spec
    return runSpec(current, args)
  }

  mock.calls = [] as MockCall<any, any>[]
  mock.isExhausted = function () {
    return queue.length === 0 && oneTimeOverrides.length === 0
  }

  function runSpec(spec: Spec, args: any[]) {
    switch (spec.type) {
      case 'return':
        mock.calls.push({ args, result: { type: 'return', value: spec.value } })
        return spec.value
      case 'lazy-return':
        const value = spec.value()
        mock.calls.push({ args, result: { type: 'return', value } })
        return value
      case 'throw':
        mock.calls.push({ args, result: { type: 'throw', error: spec.error } })
        throw spec.error
      case 'exec':
        try {
          const value = spec.implementation(...args)
          mock.calls.push({ args, result: { type: 'return', value } })
          return value
        } catch (error) {
          mock.calls.push({ args, result: { type: 'throw', error } })
          throw error
        }
      case 'not-ready':
        throw new MockNotConfiguredError()
      default:
        throw new UnreachableCaseError(spec)
    }
  }

  function reset(newSpec: Spec) {
    spec = newSpec
    queue = []
    oneTimeOverrides = []
  }

  mock.returns = function (value: any) {
    reset({ type: 'return', value })
    return mock
  }

  mock.returnsOnce = function (value: any) {
    queue.push({ type: 'return', value })
    return mock
  }

  mock.throws = function (error: any) {
    reset({ type: 'throw', error })
    return mock
  }
  mock.throwsOnce = function (error: any) {
    queue.push({ type: 'throw', error })
    return mock
  }

  mock.executes = function (implementation: (...args: any[]) => any) {
    reset({ type: 'exec', implementation })
    return mock
  }
  mock.executesOnce = function (implementation: (...args: any[]) => any) {
    queue.push({ type: 'exec', implementation })
    return mock
  }

  mock.resolvesTo = function (value: any) {
    reset({ type: 'return', value: Promise.resolve(value) })
    return mock
  }
  mock.resolvesToOnce = function (value: any) {
    queue.push({ type: 'return', value: Promise.resolve(value) })
    return mock
  }

  mock.rejectsWith = function (error: any) {
    reset({ type: 'lazy-return', value: () => Promise.reject(error) })
    return mock
  }
  mock.rejectsWithOnce = function (error: any) {
    queue.push({ type: 'lazy-return', value: () => Promise.reject(error) })
    return mock
  }

  mock.given = function (...args: any[]) {
    return {
      returnsOnce(value: any) {
        oneTimeOverrides.push({ args, spec: { type: 'return', value } })
        return mock
      },

      throwsOnce(error: any) {
        oneTimeOverrides.push({ args, spec: { type: 'throw', error } })
        return mock
      },

      executesOnce(implementation: (...args: any[]) => any) {
        oneTimeOverrides.push({ args, spec: { type: 'exec', implementation } })
        return mock
      },

      resolvesToOnce(value: any) {
        oneTimeOverrides.push({ args, spec: { type: 'return', value: Promise.resolve(value) } })
        return mock
      },

      rejectsWithOnce(error: any) {
        oneTimeOverrides.push({ args, spec: { type: 'lazy-return', value: () => Promise.reject(error) } })
        return mock
      },
    }
  }

  if (defaultImpl) {
    mock.executes(defaultImpl)
  }

  return mock
}