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Version: 6.6

makeRenderRestHook()

function makeRenderRestHook(makeProvider: ProviderType): RenderRestHookFunction;

makeRenderRestHook() is useful to test hooks that rely on the rest-hooks. It creates a renderRestHook() function that mirrors @testing-library/react-hooks's renderHook() but does so with a <Suspense/> boundary as well as in a <Provider /> context.

Arguments​

makeProvider​

type ProviderType = (
  managers: Manager[],
  initialState?: State<unknown>,
) => React.ComponentType<{
  children: React.ReactChild;
}>;

Function to generate the provider used in renderRestHook(). The purpose of this is to unify construction of providers as they both are initialized in a very different fashion.

renderRestHook()​

Returned from makeRenderRestHook():

type RenderRestHookFunction = {
  <P, R>(
    callback: (props: P) => R,
    options?: {
      initialProps?: P;
      initialFixtures?: FixtureEndpoint[];
      resolverFixtures?: FixtureEndpoint[];
      wrapper?: React.ComponentType;
      // @deprecated
      results?: Fixture[];
    },
  ): {
    readonly result: {
      readonly current: R;
      readonly error: Error;
    };
    readonly waitForNextUpdate: () => Promise<void>;
    readonly unmount: () => boolean;
    readonly rerender: (hookProps?: P | undefined) => void;
  };
  cleanup(): void;
};

renderRestHook() creates a Provider context with new manager instances. This means each call to renderRestHook() will result in a completely fresh cache state as well as manager state.

Arguments​

callback​

Hooks to run inside React. Return value will become available in result

options.initialFixtures​

Can be used to prime the cache if test expects cache values to already be filled. Takes same array of fixtures as MockResolver

This has the same effect as initializing <CacheProvider /> with mockInitialState()

options.resolverFixtures​

These fixtures are used to resolve any new requests. This is most useful for mocking imperative fetches like mutations, but can also allow testing suspending states or transitions.

Wrrks by adding MockResolver as a wrapper.

options.initialProps​

The initial values to pass to the callback function

options.wrapper​

Pass a React Component as the wrapper option to have it rendered around the inner element

cleanup()​

Cleans up all managers used in tests. Should be run in afterEach() to ensure each test starts fresh.

Returns​

  • result (object)
    • current (any) - the return value of the callback function
    • error (Error) - the error that was thrown if the callback function threw an error during rendering
  • waitForNextUpdate (function) - returns a Promise that resolves the next time the hook renders, commonly when state is updated as the result of a asynchronous action.
  • rerender (function([newProps])) - function to rerender the test component including any hooks called in the callback function. If newProps are passed, the will replace the initialProps passed the the callback function for future renders.
  • unmount (function()) - function to unmount the test component, commonly used to trigger cleanup effects for useEffect hooks.

@testing-library/react-hooks reference

Example​

import { makeRenderRestHook, makeCacheProvider } from '@rest-hooks/test';

const payload = {
  id: 5,
  title: 'hi ho',
  content: 'whatever',
  tags: ['a', 'best', 'react'],
};

beforeEach(() => {
  nock('http://test.com')
    .get(`/article-cooler/${payload.id}`)
    .reply(200, payload);
  renderRestHook = makeRenderRestHook(makeCacheProvider);
});

it('should resolve useSuspense()', async () => {
  const { result, waitForNextUpdate } = renderRestHook(() => {
    return useSuspense(ArticleResource.get, payload);
  });
  expect(result.current).toBeUndefined();
  await waitForNextUpdate();
  expect(result.current instanceof ArticleResource).toBe(true);
  expect(result.current.title).toBe(payload.title);
});