Error "does not have an entry point." in Projects that do not have an Entry Point

I have a project that consists of a set of development tools that compile a .dll, to maintain the quality use a project dedicated to code tests and try to add a report of code coverage.

Due to the Continuous Integration system, I use NUnit + Travis + Monocov

But when executing the following command:

mono --profile=log:coverage MiProyecto.Test.dll

I get the following error message:

Using default runtime: v4.0.30319
Assembly 'MiProyecto.Test.dll' doesn't have an entry point.

I understand that it looks for a main () method as an entry point, but a project destined to be a dll library does not have to have a main () method.

Is there an alternative to generate the coverage report?