Are the snippets in the code block working or not ?
Topic on VisualEditor/Feedback
As said below, we are not sure what you are talking about, although probably @Tchanders can also help here.
This is the code editor extension which is based on the ace editor widget. It is used for autocompletions and snippets
This is also used in the visual editor sandbox version. ( example in the insert math formula )
I want to know whether the snippets completions are working the visual editor or not.
If yes, how ?
It does not seem like autocompletion and snippets are enabled for the VE version of the editor indeed. I noticed before that the VE version does not do the same setup as the plain text version of the Editor. That setup routine should probably be factored out so that it can be used by both plugins.
Please do file a bug report.
P.S. for those who want to test, you can use ctrl-spacebar while using the editor on for instance an Javascript blob and this should show you a list of autocompletions and predefined snippets.