Import existing undo/redo history when initializing the Undoo instance

[Vadorequest]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[ ] Bugfix
[x] Feature
[ ] Code style update (formatting, local variables)
[x] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[x] Documentation content changes
[ ] Other... Please describe:

What is the current behavior?

Not possible to preload an existing history. History gets lost during page refresh and there is no way around that.

Issue Number:

• POC with Next.js and feedback #41

What is the new behavior?

Added an option initialHistory as UndoProps to preload an initial history when initializing the undoo instance.

Allows preserving the undo/redo history (e.g: local storage) and reload it even when the history gets lost (e.g: page refresh).

Also, added tests using @testing-library for the useUndo hook. 🎉
And added Storybook story for useUndo examples.

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

I first refactored the Undo.stories.tsx by using a Storybook "Template" component, but I noticed it was harder to understand the documentation when doing so.
So, I changed it back in UnlyEd@72d1ddc

See storybookjs/storybook#13657 (comment) for in-depth explanation.

I don't personally like duplicating all that code, but I noticed that's what has been done so far in other stories, and I believe the point of having Storybook is to favour documentation quality and understanding rather than code reusability.

[Vadorequest]

@amcdnl PR ready, please review ;)

[Vadorequest]

Made some improvements/changes. Ready to be merged IMHO.

[amcdnl]

This has to be inside the ref otherwise its recreated every render

[Vadorequest]

I need to reuse the undoo to use undoo.import() below, how do I keep track of the undoo reference if it's inside the ref?

Would you mind fixing this? I don't really see how it can be done.

[Vadorequest]

I tried doing the following, but it didn't pass the tests:

  const manager = useRef<Undoo>(
    new Undoo({
      maxLength: maxHistory
    })
  );

  useEffect(() => {
    if (Array.isArray(initialHistory)) {
      manager?.current?.undoo?.import(initialHistory);
    }
  }, [initialHistory, manager]);

[amcdnl]

You shouldn't need to pass a ref in the dep array.

[Vadorequest]

Maybe, (but then eslint complains about it), but it doesn't fix the implementation.

I don't understand how to do that, might be simpler if you take a look yourself, if you have the time.

[amcdnl]

What did the tests complain about?

[Vadorequest]

The last test didn't pass anymore. It basically broke the feature. Here's the output:

It's this test, which initializes with an existing history, but "undoing" doesn't restore it anymore:

  test('should allow to load an initial history', () => {
    // Renders the component, make "screen" available
    render(
      <UndoRedoMockComponent
        initialHistory={[{ nodes: [{ id: '1' }, { id: '2' }], edges: [] }]}
      />
    );

    expect(
      screen.getByTestId('output'),
      'Should be initialised with 0 nodes and 0 edges'
    ).toHaveTextContent('There are 0 nodes and 0 edges.');

    fireEvent.click(screen.getByText('Undo'));
    expect(
      screen.getByTestId('output'),
      'Undoing should go back to the previous state of the history, which contains 2 nodes and 0 edges'
    ).toHaveTextContent('There are 2 nodes and 0 edges.');
  });

[Vadorequest]

I fixed the small stuff, need your help regarding the undoo manager ref stuff.

[Vadorequest]

@amcdnl Could you have a look at this?

If you can't fix it, I suppose we should extract the new feature from the test and make another PR with the tests only, so we can merge it and increase tests coverage. (and have the feature in another PR)

[amcdnl]

@Vadorequest - Given the age, I'm going to close this PR. If its still something relevant let's reopen and start discussions.

[Vadorequest]

@amcdnl I think at minimum it should be broken into 2 PR, one with the tests, and one with the new feature. The tests could/should be merged right away, but I needed your help on the feature.

[amcdnl]

Push up tests and lets itterate on other