json 2.0 bug: wrong behavior for parsing empty value

[Sorin Marian Nasoi]

Parsing an empty value has wrong behavior for both JSON mappings (Snelson and JSON-ML).
Please see failing tests:
- test/rbkt/zorba/json/json-snelson-empty-value
- test/rbkt/zorba/json/json-jsonml-empty-value

For instance in zorba/json/json-snelson-empty-value.xq:

import module namespace json = "http://www.zorba-xquery.com/modules/converters/json";
json:parse(<a/>)

Should raise error(s) http://www.zorba-xquery.com/errors:ZJPE0001
But instead Zorba returns a result.

For test/rbkt/zorba/json/json-jsonml-empty-value.xq:

import module namespace json = "http://www.zorba-xquery.com/modules/converters/json";
let $options :=
  <options xmlns="http://www.zorba-xquery.com/modules/converters/json-options">
    <json-format value="JsonML-array"/>
  </options>
json:parse(<a/>,$options)

Zorba returns http://www.w3.org/2005/xqt-errors:XPST0003
instead of http://www.zorba-xquery.com/errors:ZJPE0001

[Paul J. Lucas (paul-lucas)]

Renamed the tests to conform to all the rest, i.e., contain "parse" or "serialize" in the test name. Also, again, the second test is invalid XQuery since it's missing a "return".

[Paul J. Lucas (paul-lucas)]

These functions are declared as taking an xs:string? as an argument. If one is able to pass something like <a/> (which is not a string), then it points to a bug elsewhere in the code, i.e., something should have checked that the actual argument type doesn't match the declared argument type -- right? If so, that's not my code.

[Paul J. Lucas (paul-lucas)]

What specification tells you that parsing an empty value should return an error?
Why isn't returning nothing valid?

[Chris Hillery (ceejatec)]

The JSON grammar is not as pedantic as I would like, but it looks like a JSON text must be exactly an object or an array.

  http://tools.ietf.org/html/rfc4627

So an empty string is not a valid instance of JSON.