Validation doens't check the variables about koa-graphql

[chentsulin]

Hi @entropitor
Could you write a failed test to demonstrate this issue?
Now, there is a test shows that it response stats 400 when receive validation error:
https://github.com/chentsulin/koa-graphql/blob/7b4d23aecf5926c9b0181d6e9e775d2a1357c9d1/src/__tests__/http-test.js#L201-L225

[entropitor]

@chentsulin You are testing the validations on the query, then it correctly returns a 400, but if there is a validation error on the variables (e.g. the value of a variable not matching the given type) then it returns a 200.

I can see if I can write a test myself soon

[chentsulin]

The codebase has been changed a lot, so this might not be reproduced anymore.