fix: limit excerpt lengths even for custom excerpts

[obenland]

Trims excerpts even if it's a custom excerpt for a uniform look.

All Submissions:

• Have you followed the Newspack Contributing guideline?
• Does your code follow the WordPress' coding standards and VIP Go coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Deprecated excerpt_length and excerpt_more methods in favor of a comprehensive excerpt callback.

Core only allows to control the length of generated excerpts, assuming that authors want to keep their custom excerpts as they're written. This PR will apply the excerpt length limit to both types of excerpts for a more uniform look.

Closes Automattic/wp-calypso#51415

How to test the changes in this Pull Request:

1. Once you checked out the branch and built the block…
2. Add a custom excerpt to a post, preferably a rather long one.
3. In a different post, insert the Homepage Posts block and manipulate the excerpt length.
4. Preview the post to make sure the front-end works as expected.

Other information:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes, as applicable?
• Have you successfully ran tests with your changes locally?

[mreishus]

Once you checked out the branch and built the block…

@obenland I'm not sure how to do this. After I run npm start in this repository, I don't see any ports open up on my machine. Do I need to copy some of the built files to a calypso installation, or my sandbox to work with them?

[obenland]

Heh, I was just thinking I should expand on the testing instructions :)

I have my newspack-blocks repo sym-linked into wp-content/plugins on a local WordPress install (I use MAMP) so I can use it as a regular plugin. Does that help?

[mreishus]

Yup, I use wp-env, and I was able to get it working by adding the directory to the plugins list in .wp-env.json.

[mreishus]

The functionality is working well:

From a code standpoint, as someone not familiar with the code, I might wonder why both filter_excerpt and filter_excerpt_length exist, since they both seem to do the same thing. However the @deprecated tag might provide enough of an explanation.

Noted a small spelling error.

[adekbadek]

Works as expected, left one question.

[matticbot]

🎉 This PR is included in version 1.39.0-alpha.1 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[matticbot]

🎉 This PR is included in version 1.39.0 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀