mono creates its own debug targets called .mdb files when you use the mcs compiler.

is there a way of using NCover or another code coverage tool with Mono?

a commandline tool would be better so I can add it to our continuous integration server.

+2  A: 

have you looked into monocov?

Mark Bessey
looks like it'll work, shame theres only a source distro
Scott Cowan
looks like the dependencies are a mess, I'm going to try to compile it again on the weekend
Scott Cowan

See the C# Test Coverage tool from Semantic Designs:

Very low overhead, handles huge systems of files, intuitive GUI showing coverage on specific files, and generated report with coverage breakdown at method, class and package levels.

Operates by instrumenting the C# source code, and needs no other support from Mono other being able to compile and run the instrumented code, so it should run fine with Mono.

Ira Baxter
sorry but mono uses different debug files .mdb instead of the .pdb files from the ms clr. so conventional code coverage tools like ncover don't work
Scott Cowan
For whoever downticked the answer, and Scott, the specific observation already made by the answer is that the SD tools do all the text coverage by operating solely on the *source* code. So there isn't any use or need for "mdb" or "pdb" files, so this is not a legitimate objection.
Ira Baxter