Improve CollectionsTest coverage of unmodifiable NavigableMaps

 - assert that head/tail maps exclusive of a present key
   have the same entries as those inclusive of the
   neighboring key in the corresponding head/tail direction.
 - cover head/tail maps whose bound is an absent key
   (previous tests only covered head/tail maps whose bound
   was a present key)
 - assert that ceiling/floor key, if present, of an absent
   key are adjacent in terms of higherKey()/lowerKey()

Since CollectionsTest.test_unmodifiableNavigableMap_*()
constructs wrappers around a TreeMap, these tests also
provide additional test coverage for TreeMap.

Test: CollectionsTest
Change-Id: I92ebe5dde301ed4a6fcd18cb5e81a65cdb0d4bc9

0 files changed, 0 insertions, 0 deletions