Portable stories: Pass story context to the play function of a composed story

[yannbf]

Closes #25877

What I did

Before, the play function in a portable story would need to receive the entire story context. Now, the context is passed internally, plus the user can still override whatever they need.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

Manual testing

import { render, screen } from '@testing-library/react';
import { composeStory } from '@storybook/react';
import { vi, test, expect } from 'vitest';
import Meta, { Primary as PrimaryStory } from './Button.stories';

// Returns a component that already contain all decorators from story level, meta level and global level.
const Primary = composeStory(PrimaryStory, Meta);

test('onclick handler is called', async () => {
  const { container } = render(<Primary />);
  // this should call the play function with a full context, not just canvasElement
  await Primary.play({ canvasElement: container });
});

Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

• Make sure this PR contains one of the labels below:

  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
  • feature request: Introducing a new feature.
  • BREAKING CHANGE: Changes that break compatibility in some way with current major version.
  • other: Changes that don't fit in the above categories.

🦋 Canary release

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core team members can create a canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=<PR_NUMBER>

[skratchdot]

@yannbf - this is causing my unit tests to fail now. i use composeStories with a custom createStoryTests which runs all my stories through wtr (using a real browser)

My code looks like:

import { ReactRenderer, composeStories } from '@storybook/react';

import { ComposedStoryFn } from '@storybook/types';
import { createElement } from 'react';
import { render } from '@testing-library/react';

type AllStories = Parameters<typeof composeStories>[0];

type ComposedStory = ComposedStoryFn<ReactRenderer, Partial<unknown>>;

const buildTest = (storyName: string, Story: ComposedStory) => {
  it(storyName, async () => {
    const { container } = render(createElement(Story));
    if (typeof Story.play === 'function') {
      await Story.play({ canvasElement: container, ...Story });
    }
  });
};

export const createStoryTests = (stories: AllStories, title?: string) => {
  const storyId =
    title ?? stories.default.title ?? 'no title specified in default export';
  describe(`Composed Story Tests: ${storyId}`, () => {
    const composedStories = composeStories(stories);
    const entries = Object.entries<ComposedStory>(composedStories);
    for (const [storyName, Story] of entries) {
      buildTest(storyName, Story);
    }
  });
};

Now every story in my codebase that does not have a play function is erroring out. Is there any way we can default to not throwing an error (or making it a config like shouldThrowError)?

Maybe changing:

storybook/code/lib/preview-api/src/modules/store/csf/portable-stories.ts

Lines 104 to 113 in 8e2a375

	play: (async (extraContext: ComposedStoryPlayContext<TRenderer, TArgs>) => {
	if (story.playFunction === undefined) {
	throw new Error('The story does not have a play function. Make sure to add one.');
	}
	await story.playFunction({
	...context,
	...extraContext,
	});
	}) as unknown as ComposedStoryPlayFn<TRenderer, Partial<TArgs>>,

to:

      play: (async (extraContext: ComposedStoryPlayContext<TRenderer, TArgs>) => {
        if (typeof story.playFunction === 'function') {
          await story.playFunction({
            ...context,
            ...extraContext,
          });
        }
      }) as unknown as ComposedStoryPlayFn<TRenderer, Partial<TArgs>>,

[skratchdot]

The workaround for me is changing:

const composedStories = composeStories(stories);

to:

const composedStories = composeStories({
  ...stories,
  default: {
    play: () => {},
    ...stories.default,
  },
});

[yannbf]

Thanks for flagging this @skratchdot, this will be fixed in the next beta release shortly!