The current VisualEditor interface has a "Save page" dialog box with an edit summary input field. However, this edit summary input field accepts wikitext, but has no preview feature for what the rendered wikitext will look like. This is a regression from the standard (non-VisualEditor) interface.
Roan said that there be a mini-editor or mini-parser or something stuck in the edit summary area at some point.
See Also: T62535: VisualEditor: Add a Preview feature to show actual version of page (minus slugs, etc.)