HTML-tags of newly registered formats disappear when pasting

[websupporter]

Describe the bug
I registered a new format type. Lets say: <span class="great-class">. When I copy a text now into the Component, the span.great-class tags get removed:

Received HTML:
df df <span class="great-class">df</span> df df. editor.min.js:55:146144
Received plain text:
df df df df df. editor.min.js:55:146187
Processed inline HTML:
df df df df df. blocks.min.js:2:115611

To Reproduce

const {createElement} = window.wp.element;
const {registerFormatType, toggleFormat} = window.wp.richText;
const {RichTextToolbarButton} = window.wp.editor;

registerFormatType('some/type', {
    title: 'Title',
    tagName: 'span',
    className: 'great-class',
    edit({ isActive, value, onChange}) {
        const onClick = () => {
            onChange(toggleFormat(value, { type: 'some/type' }));
        };

        return (
            createElement(RichTextToolbarButton, {
                icon: 'admin-home',
                title: 'Title',
                onClick,
                isActive,
                shortcutType: 'primary',
                shortcutCharacter: '8',
            })
        )
    }
});

1. Add this script
2. Add a text in a RichText component
3. Select a part of the text and click the new button in the toolbar
4. Copy all the text in the clipboard
5. Paste the text in a RichText component
6. See error

Expected behavior
The new format should survive the copy/pasting

Screenshots
https://www.youtube.com/watch?v=9SiyAROa1Iw

Desktop (please complete the following information):

• OS: Ubuntu 14.04
• Browser Firefox

[websupporter]

I suspect, this could be fixed by expanding the list returned by getPhrasingContentSchema() with the types we get from wp.data.select('core/rich-text').getFormatTypes()

gutenberg/packages/blocks/src/api/raw-handling/phrasing-content.js

Line 35 in a92216b

return phrasingContentSchema;

But for <span> this might be also a problem:

gutenberg/packages/blocks/src/api/raw-handling/phrasing-content-reducer.js

Lines 16 to 40 in a92216b

	if ( node.nodeName === 'SPAN' ) {
	const {
	fontWeight,
	fontStyle,
	textDecorationLine,
	verticalAlign,
	} = node.style;
	if ( fontWeight === 'bold' || fontWeight === '700' ) {
	wrap( doc.createElement( 'strong' ), node );
	}
	if ( fontStyle === 'italic' ) {
	wrap( doc.createElement( 'em' ), node );
	}
	if ( textDecorationLine === 'line-through' ) {
	wrap( doc.createElement( 'del' ), node );
	}
	if ( verticalAlign === 'super' ) {
	wrap( doc.createElement( 'sup' ), node );
	} else if ( verticalAlign === 'sub' ) {
	wrap( doc.createElement( 'sub' ), node );
	}

[skorasaurus]

Thanks for reporting; I'm not able to reproduce this using your example; nor in my custom example of a custom richtext format.

Looks like this was fixed a while back in #27967 (ref #16240)

[websupporter]

Amazing. Thanks for following up @skorasaurus