Graphql-js: Custom Scalar types are not validated on query variables

[pyros2097]

I have a mutation which has a custom scalar type in the input field,

// Scalar Type
var PLString = new GraphQLScalarType({
    name: "PLString",
    serialize: value => {
      return value
    },
    parseValue: value => {
      return value
    },
    parseLiteral: ast => {
      throw new Error("This string is not valid")
      return ast.value
    }
  })
}

This is my mutation,

mutation: new GraphQLObjectType({
    name: 'Mutation',
    fields: {
      login: {
        type: GraphQLString,
        args: {
          text: { type: PLString }
        },
        resolve: () => "Immutant"
     }
    }
});

When I make a graphql mutation like this,

mutation PL {
  login(text: "this is text")
}

I get the error

{
  "errors": ["This string is not valid"]
}

But when I do this with query variables like this,

mutation PL($input: GraphQLString) {
  login(text: $input)
}

//variables
{
  "input": "this is text"
}

It succeeds

{
  "data": {
     "login": "Immutant" 
   }
}

Is this the expected behavior of GraphQL or is this a problem with the js implementation

[pyros2097]

Well I have fixed it .. I just needed to throw the error in the parseValue part also and then it works. So that validation logic has to be implemented in the parseLiteral and parseValue functions.