BiocManager::valid() does not check for 'missing' dependencies

[mtmorgan]

Suppose Package A depends on B depends on C. The user installs A (hence B & C) then removes B. BiocManager::valid() does not detect this situation, because A and C are at the most recent version, but the installation is clearly broken.

I would be happy to work on a pull request if this is useful.

[LiNk-NY]

Hi Martin, @mtmorgan

I think this would be useful if not too onerous to check.

PS. The docs should be more accurate about the ... param in ?valid().

Thank you!

-Marcel