Is there any lightweight C# IDE I could embedd?

I'm about to implement a kind of specific testing center for unit testing of automation controllers code units. My idea was to use c# as the language for unit tests. To do that I would like to embedd some kind of c# IDE into the testing application. I'd like it to have syntax highlight,intellisense,and ability to build(or show compiler errors). Does something like that exist? I have found some reference to a tool called Actipro, is there anything else out there?

Thanks