REPL environment for teacher assignments As a teacher on an IT high school, I am teaching the basics of C#, JavaScript and PHP (in different years of their study of course)
For about 3 years I had been happily using the repl.it classrooms. In this environment the pupil could

see the assignment
write and execute code
interact with the console

and I could

inspect his/her code
execute it
give comments
see whether he had tried and/or submitted
Also, depending on the language

I could either set some of his/her submissions as finished
or they simple passed all unit tests and were closed automatically.



However, repl.it had announced the clousure of its classrooms at the end of 2020, replacing it with Repl teams, which are an immature product much less reliable and comfortable compared to the previous classrooms, lacking some of its features
I am looking for any suggestions for an enviroment we could migrate to. I know big universities usually have their own closed systems. But, it there some service that is open to public, for a reasonable fee?
I have been teaching with Cocalc for a few years. It has most of the features you are looking for, but unless you are using python with nbgrader there is perhaps not much support for unit tests/autograding. It's not perfect but it gets the job done, with less frustration to me than trying to grade this stuff in Canvas. Also, I can rely on the simplicity of identical environments, no more babysitting each student's installation and worrying about Windows vs Mac setup, etc.
Cocalc allows the creation of &quot;courses&quot; where each student can receive &quot;Assignments&quot; and &quot;Handouts&quot; from the instructor. The students' projects are self-contained VMs and you can do a bit of central administration on them. They can use free ones, or upgrade for a small fee. You can do some LMS-type things there too, such as grade and comment on returned work. Here's a link to the Teaching documentation. There are a good amount of videos and blog posts put up by other enthusiasts as well.