Introduce GraphQL Normalizer

[ostridm]

When working with GraphQL documents, it's essential to ensure that the structure conforms to a normalized format to prevent inconsistencies and improve compatibility with various tools and libraries.

Proposed solution

Implement a GraphQLNormalizer in @har-sdk/core package, make sure the GraphQLImporter executes normalization upon successful deserialisation of an introspection query or conversion of SDL schema.

Considerations

• Use the IntrospectionQuery type definitions as a reference.
• Ensure the non-optional properties are present in case the properties format are obvious, e.g.
  • Normalizing the kind property for query, mutation, and subscription types to 'OBJECT' if they are not already specified
  • Normalizing the structure of directives and types (including object types, interface types, union types, and input object types), fields, interfaces, possible types, input fields, and arguments by ensuring the unexpected null arrays are superseded with empty ones

Expected results

The GraphQL normalizer, given a non-compliant document, should normalize it as follows:

{
  url: 'https://example.com/graphql',
  data: {
    __schema: {
      description: null,
      queryType: {
---     name: 'Query'
+++     name: 'Query',
+++     type: 'OBJECT' 
      },
      mutationType: null,
      subscriptionType: null,
      types: [
        {
          kind: 'OBJECT',
          name: 'Foo',
          description: null,
          specifiedByURL: null,
          fields: [
            {
              name: 'bar',
              description: null,
---           args: null,
+++           args: [],
              type: {
                kind: 'NON_NULL',
                name: null,
                ofType: {
                  kind: 'SCALAR',
                  name: 'String',
                  ofType: null
                }
              },
              isDeprecated: false,
              deprecationReason: null
            }
          ],
          inputFields: null,
---       interfaces: null,
+++       interfaces: [],
          enumValues: null,
          possibleTypes: null
        }
      ]
    }
  }
}