Ranges can be either end-inclusive or end-exclusive.

An end-inclusive range, with 2 periods, looks like:

(3 .. 7).to_a
#=> [3, 4, 5, 6, 7]

An end-exclusive range, with 3 periods, looks like:

(3 ... 7).to_a
#=> [3, 4, 5, 6]

Mongoid handles end-inclusive ranges correctly, with:

{"$gte" => 3, "$lte" => 7}

But it should also handle end-exclusive ranges correctly, with:

{"$gte" => 3, "$lt" => 7}

Mongoid currently ignores whether a range is end-exclusive, and always generates queries as though the range were end-inclusive.

This is tested as of v2.5.1.