How to validate value/type of directive argument while schema validation?

[LastDragon-ru]

I want to detect if the value of the argument has a valid type or not, eg in

directive @a(a: String!) on FIELD_DEFINITION

type Query {
    a: String @a(a: {a: 123})
}

the expected error should be something like "@a(a) must be String".

But the schema passes the validation 😱

BuildSchema::build($schema)->assertValid(); // no error :(

Am I missing something?

[spawnia]

I believe validation for this is simply not implemented as of now. The reference implementation graphql-js also seems to lack it - see graphql/graphql-js#1389. Since we base this library off of them, it just has not been added. Open for pull requests though!

[LastDragon-ru]

Ok, thanks.