MongoDd: fixed expiration support and removed duplicated tests

[marc-mabe]

with an edge case in MongoDb::internalGetItem()

[Maks3w]

Any possibility of add a test?

[marc-mabe]

I have seen a test failure in the develop branch. I'll check if the test fails also in master else I add it.

[marc-mabe]

@Maks3w I found out that the test MongoDbTest::testCachedItemsExpire only failed sometimes (see https://travis-ci.org/marc-mabe/zend-cache/jobs/87353080) and noticed that the expiration feature wasn't correctly defined in capabilities. It was minTtl=0 which means this adapter doesn't support expiration of items. So I fixed the capabilities and also removed all capabilities that are not needed to define because of default.

I also noticed that MongoDB natively supports expiration of items by an index but this index wasn't defined -> so I added this index.

• MongoDB 3.0 https://docs.mongodb.org/manual/tutorial/expire-data/#expire-documents-at-a-specific-clock-time
• MongoDb 2.2 https://docs.mongodb.org/v2.2/tutorial/expire-data/
• https://github.com/marc-mabe/zend-cache/blob/hotfix/MongoDb_fixed_undef_var_key/src/Storage/Adapter/MongoDbResourceManager.php#L106

-> Because this index will only be defined if the collection wasn't pushed into the resource manager I leave the logic in the adapter intact so it will also work with the index.

At this point I also removed the duplicated tests:

• MongoDbTest::testCachedItemsExpire() already done by CommonAdapterTest::testGetItemReturnsNullOnExpiredItem()
• MongoDbTest::testFlush() already done by CommonAdapterTest::testFlush()

[Maks3w]

I've doubts about what expire strategy is tested then. I think we need two test cases for test when MongDb is who expire or when the defined logic

[marc-mabe]

mh I don't know why but if I remove the adapter logic to handle expired items all TTL tests fails even with this index set : https://travis-ci.org/marc-mabe/zend-cache/jobs/88634000

So the logic for handling of expired items needs to be in the adapter even with this index and the logic gets covered with the current tests.

[Maks3w]

Ok. Seems the expires index is a new feature and its not related with the original issue.

If it is correct could you split the PR and propose the index feature as enhancement?

[marc-mabe]

@Maks3w I removed the line enabling the special index.
(I'll create a new PR for it later)

[marc-mabe]

mh coverage for the Storage/Adapter/MongoDb.php increased from 82.0 to 82.29 but APC related coverage get reported as 0 -> I have no idea why as I didn't change something related to it.

[marc-mabe]

merged with 5cda324 and d2cf8dd