Angular: Fix Angular template error for props with a circular reference

[Marklb]

Closes #25275, #16855

What I did

For Angular stories, two templates are generated. One for the template that will be used for rendering and another that will be used for displaying source. The problem is the way objects are handled for the source template. This provides a fix for the circular reference case.

The computesTemplateSourceFromComponent attempts to replace input props with a value, instead of the variable. It relies on createAngularInputProperty, which uses JSON.stringify then applies some formatting replacements. The problem is that JSON.stringify does not handle circular references.

The solution I went with as an initial attempt is to use a replacer that replaces the circular reference with "[Circular]". If there is a better convention then that can be changed. I wasn't sure what the best solution would be, so I just picked something.

As an example of my current solution, assume I have the following:

const MyStory = {
  render: args => {
    const obj = { a: 'b' };
    obj.ref = obj;
    return {
      props: {
        input1: obj,
      },
    };
  },
};

The resulting source template should be similar to the following:

<story-comp [input1]="{a: "b", ref: "[Circular]"}" ></story-comp>

I added a test for this scenario angular source decorator > with argTypes (from compodoc) > should handle circular object as stringified. Also, I added tests for the computesTemplateFromComponent and updated a few test descriptions to not start with an uppercase, for consistency.

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

This section is mandatory for all contributions. If you believe no manual test is necessary, please state so explicitly. Thanks!

This is a matter of stringifying an object, so I don't think a manual testing process is necessary. I can try to find a spot to put a story, if needed. Running the unit test should be enough, but if you want to use a sandbox then you can pass an object to and input prop. The docs addon would also need to be loaded, so sourceDecorator gets called.

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

This PR does not have a canary release associated. You can request a canary release of this pull request by mentioning the @storybookjs/core team here.

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>

[greptile-apps]

PR Summary

• Added stringifyCircular function in /code/frameworks/angular/src/client/angular-beta/ComputesTemplateFromComponent.ts to handle circular references in props.
• Updated createAngularInputProperty to use stringifyCircular for safe stringification.
• Introduced new test cases in /code/frameworks/angular/src/client/angular-beta/ComputesTemplateFromComponent.test.ts for circular references and various Angular component selectors.
• Modified /code/frameworks/angular/src/client/angular-beta/__testfixtures__/input.component.ts to include an optional ref property in ISomeInterface for circular reference handling.

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[valentinpalkovic]

LGTM!

Thank you for such a descriptive PR description and the fix!

Also, thank you for enhancing our test suite. <3