Hej folks,

when using the validation rule in combination with a query that provides a variable with a default value, the @include (and potentially also the @skip) directive is causing troubles.

GraphQLError: Argument "if" of required type "Boolean!" was provided the variable "$shouldSkip" which was not provided a runtime value.

I was able to reproduce this with a test case, and I'm wondering what the expected behavior is here.

it('should respect @include(if: false) via default variable value', () => {
  const ast = parse(`
    query Foo ($shouldSkip: Boolean = false) {
      variableScalar(count: 10) @include(if: $shouldSkip)
    }
  `);

  const complexity = getComplexity({
    estimators: [
      simpleEstimator({defaultComplexity: 1})
    ],
    schema,
    query: ast
  });
  expect(complexity).to.equal(0);
});

I see that you're only using graphql-js's getDirectiveValues, which under the hood has a logic that throws the error here.

But to me it sounds like it should first check for the query document default variables.

I feel like we have two options here:

1. obtain default variables from operation definition here and add these to this.options.variables (or a derivate object of it).
2. try to convince graphql-js maintainers that there's a flaw in their flow of obtaining runtime values.

As the graphql-js library does not seem to have issues with @include directives, I'm leaning towards (1), wdyt?