This changes the parsing grammar and validation rules to more correctly implement the current state of the GraphQL SDL proposal (facebook/graphql#90)
ref: graphql/graphl-js#1102
specification.
The framework currently coerces query variables similar to the way it
treats output values, which means it attempts to coerce the value into
the field's corresponding data type regardless of the received value.
According to items 3f and 3g in section 6.1.2
(http://facebook.github.io/graphql/#sec-Validating-Requests) of
Facebook's GraphQL specification query variables should be coerced
according to their type's input coercion rules laid out in section
3.1.1 (http://facebook.github.io/graphql/#sec-Scalars). If the value
can not be coerced into the correct type according the the input
coercion rules for the type a query error should be thrown. This
ensures that client provided query variables were of the correct format
and will be a valid format and type by the time they are passed into an
implementing resolver.
This patch fixes the above issue by updating the way query variables
are sanitized during the process of parsing the query. It directly
follows the rules for scalar input coercion laid out by the
specification and throws query errors when a value that cannot be
coerced to the correct type is given. Tests for isValidPHPValue will
also be updated to ensure that it is doing the correct type checks on
Values::isValidPHPValue for the given type and value provided. A new
test case will also be added to test Values::getVariableValues and make
sure it is also enforcing the scalar input coercion rules and throwing
errors for invalid values.
