I have this interface:

public interface IDiffMatchAligner<T>
{
[NotNull]
IEnumerable<DiffElement<T>> Align(Slice<T> slice1, Slice<T> slice2);
}

At some point, the Slice<T> types there were IList<T>, but have subsequently been replaced everywhere.

Build of this class library fails with this error message:

BasicInsertDeleteDiffMatchAligner.cs (7, 57): 'BasicInsertDeleteDiffMatchAligner<T>' does not implement interface member 'IDiffMatchAligner<T>.Align(IList<T>, IList<T>)'

Here is the class definition that it complains about:

public class BasicInsertDeleteDiffMatchAligner<T> : IDiffMatchAligner<T>
{
[NotNull]
public virtual IEnumerable<DiffElement<T>> Align(Slice<T> slice1, Slice<T> slice2) =>
slice1.Select(element => new DiffElement<T>(element, new Option<T>(), DiffOperation.Delete))
.Concat(slice2.Select(element => new DiffElement<T>(new Option<T>(), element, DiffOperation.Insert)));
}

I had this problem once earlier (exact same error, files exactly as above) and fixed it by hitting "Reload and rebuild selected component" on the assembly in the ncrunch tests pane, but now can't seem to shake this problem.

No build warnings, the project builds and runs all unit tests successfully using ReSharper unit-test runner.

Unfortunately the build issue rectified itself because I managed to change the interface definition by a linefeed to it, this seems to have forced a refresh of the offending file and now everything builds. Good for my progress, but sucks for troubleshooting and figuring out if this is a bug in NCrunch or something else.

Not been able to reproduce it forcibly. I did that earlier but no matter what I did everything worked nicely in that project.

All the classes and interfaces are in one project, all the unit-tests in another. The interface and the class is in the same project.

This has only happened in VS 2015.