fix empty rules object that should return an empty object instead of false

[fifthaxe]

Fix the following bad falsy eval :
=============== >8 ================
rules : {}
data : {}
return : false
=============== 8< ================

As seen in jsonlogic.com playground, a rule defined as an empty object should be evaluated as an empty object instead of a falsy.

[codecov-io]

Codecov Report

Merging #23 into master will increase coverage by 0.15%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #23      +/-   ##
==========================================
+ Coverage    89.2%   89.35%   +0.15%     
==========================================
  Files           6        6              
  Lines         639      639              
==========================================
+ Hits          570      571       +1     
+ Misses         51       50       -1     
  Partials       18       18

[diegoholiveira]

@fifthaxe can you write a test to make sure this bug will never comer back in the future?

thanks anyway :)

[fifthaxe]

The tests are based on definitions from http://jsonlogic.com/tests.json, the empty rule object case is not covered. Will you consider that asking for a fix in http://jsonlogic.com/tests.json will be a good solution since this case will then be covered (and tested) by our implementation ?

[diegoholiveira]

The tests are based on definitions from http://jsonlogic.com/tests.json, the empty rule object case is not covered. Will you consider that asking for a fix in http://jsonlogic.com/tests.json will be a good solution since this case will then be covered (and tested) by our implementation ?

Sure. This is too general and would be great to be in the tests.json, but meanwhile, we can solve it here, no need to wait until it be available at tests.json.

[fifthaxe]

Ok so it seems we are done with this PR.
I also have opened an issue to Jeremy Wadhams. Take a look at it jwadhams/json-logic#21.