Regression on ref to empty schema crashes JSCK

[cxreg]

Starting in 0.2.8 this throws a fatal error. It only appears to happen if you have a reference to an empty schema. An empty schema by itself is fine as are refs in other situations.

var jsck = require("jsck").draft4;
var validator = new jsck({
    "type": "object",
    "properties": { "foo": { "$ref": "#/definitions/foo" } },
    "definitions": { "foo": {} }
});
var res = validator.validate({ "foo": "bar" });

I get this error

count@bumba:~/jsck-test$ ./crash-0.3.0.js

/home/count/jsck-test/node_modules/jsck/lib/validator.js:316
return (_ref1 = _this.uris[uri])._test.apply(_ref1, args);
^
TypeError: Cannot call method 'apply' of undefined
at /home/count/jsck-test/node_modules/jsck/lib/validator.js:316:54
at /home/count/jsck-test/node_modules/jsck/lib/draft4/objects.js:52:15
at Object.test_function as _test
at Object.validate (/home/count/jsck-test/node_modules/jsck/lib/validator.js:109:22)
at Validator.validate (/home/count/jsck-test/node_modules/jsck/lib/validator.js:94:34)
at Object. (/home/count/jsck-test/crash-0.3.0.js:11:21)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)

[automatthew]

Thanks. Will investigate as soon as I can.

[cxreg]

I've dived into this a little bit. I'm not 100% sure why the scoping changes around uri exposed this, but what is happening is that the empty schema fails is_schema because none of the properties are present. That causes it never to call compile() on this schema, and thus the _test method is never assigned.

It seems like is_schema should not be duck typing, since contextually we should know whether or not a schema is expected in a given spot, is that not so?

If it can't be fixed that way, it seems like maybe just conditionally not executing _test if it's not defined is a safe fix

[automatthew]

It seems like is_schema should not be duck typing, since contextually we should know whether or not a schema is expected in a given spot, is that not so?

I think I added is_schema so JSCK could handle structural nesting. E.g.

definitions:
  user:
    create:
      type: 'object'
      required: ['email', 'password']
    update:
      type: 'object'

[automatthew]

If it can't be fixed that way, it seems like maybe just conditionally not executing _test if it's not defined is a safe fix

Maybe. That would produce correct behavior for this case. I think the underlying problem is in the compile_definitions logic. It is plausible that an object in the schema document might be both a valid schema and a container of other schemas. Bad form to do so, in my opinion, but possibly something JSCK should support.

Here's my first thought on how to fix it:

    compile_definitions2: (context, object) ->
      if @is_schema(object)
        @compile(context, object)
      if @test_type "object", object
        for name, definition of object when not_schema_keyword(name)
          @compile_definitions context.child(name), definition

[automatthew]

not_schema_keyword

Clever.

[automatthew]

@cxreg, this branch appears to fix the original problem, while also somewhat rigorizing the approach.

https://github.com/pandastrike/jsck/tree/97-ref-to-empty

[cxreg]

Interesting. I think you still need the @test_type "object" conditionalizing @is_schema so as not to throw TypeError on numbers, strings, null, etc? Would that only happen on a malformed schema? Still probably bad.

This does look like a better approach if you are happy with the results.

[automatthew]

I moved the type test to the top of compile_definitions, to simplify the logic there, leaving is_schema as a function with implied type of object. Perhaps I should inline it.