When nil or empty string are not allowed, they are not valid.

Allow infinite values for validates_length_of. Particularly useful
for prettily defining an open ended range such as

validates_length_of :human_stupidity, :within => 0..Float::INFINITY

Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Failing test for validates_length_of, when both too_short and too_long messages are set [#5283 state:open]
Signed-off-by: NJosé Valim <jose.valim@gmail.com>

removed use of AR in AMo tests and removed testing of scopes (:on) in individual validation tests and moved them to their own test file

Signed-off-by: NJosé Valim <jose.valim@gmail.com>

Compile length validator options still at the class level, so whenever the validator is called, it just needs to check for :maximum, :minimum and :is values.

No need to use ValidationsRepairHelper hack on ActiveModel anymore, Model.reset_callbacks(:validate) is enough. However, tests in ActiveRecord are still coupled, so moved ValidationsRepairHelper back there.

Signed-off-by: NJosé Valim <jose.valim@gmail.com>
Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

Signed-off-by: NJosé Valim <jose.valim@gmail.com>