Visual Studio has an attribute called ExcludeFromCodeCoverage to exclude a method from code coverage. But when you use Linq the predicate is included. See sample screenshot below where the code is called with an empty list in the repository.
Looking deeper you could discover the reason in the code coverage results pane.
Linq generates a method for the predicate and uses a delegate to the method. This is generated at compile time. Some code coverage frameworks offer the option to exclude attributes (like ExcludeFromCodeCoverage) and adding CompilerGenerated would do the trick. Visual studio code coverage seems to have support for customization also.
💡 read The Art of Unittesting by Roy Osherove
- is this really necessary?
- isn’t there something wrong with my tests?
- should I simply write more tests?