Certain actionbuilder tests declare dependencies that don't exist on the filesystem. This should not produce a valid action.

The following discussion from BuildGrid/recc!207 (merged) should be addressed:

• @mhadjimichael started a discussion: (+6 comments)

  nit: do we have an easy way of checking if everything has been done, just in case we missed any edge cases? e.g. comparing size in vs size out?

As the above discussion states, we should assert that the declared or found dependencies are actually available when later finding and reading them from the filesystem. Certain tests in actionbuilder.t.cpp take advantage of the fact that this is not checked.

Ideally, an error should be thrown if the size of the deps set, doesn't equal the size of the file digest map used in actionbuilder.cpp.