The resolvers generates incorrect return values for array of string or null

[sabith-th]

Description

When the return type is [String]! in schema the generated resolver return type is incompatible

Steps to reproduce

Schema:

type Episode {
  directors: [String]!
  guestStars: [String]!
  writers: [String]!
}

type Query {
  episodes: [Episode]!
}

Generated Interface from graphqlgen

export interface Episode {
  directors: string[] | null;
  guestStars: string[] | null;
  writers: string[] | null;
}

Generated Resolver

export const Episode: EpisodeResolvers.Type = {
  ...EpisodeResolvers.defaultResolvers
};

Generated Default Resolvers

export namespace EpisodeResolvers {
  export const defaultResolvers = {
    directors: (parent: Episode) =>
      parent.directors === undefined ? null : parent.directors,
    guestStars: (parent: Episode) =>
      parent.guestStars === undefined ? null : parent.guestStars,
    writers: (parent: Episode) =>
      parent.writers === undefined ? null : parent.writers
  };

  export type DirectorsResolver =
    | ((
        parent: Episode,
        args: {},
        ctx: Context,
        info: GraphQLResolveInfo
      ) => Array<string | null> | Promise<Array<string | null>>)
    | {
        fragment: string;
        resolve: (
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>;
      };

  export type GuestStarsResolver =
    | ((
        parent: Episode,
        args: {},
        ctx: Context,
        info: GraphQLResolveInfo
      ) => Array<string | null> | Promise<Array<string | null>>)
    | {
        fragment: string;
        resolve: (
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>;
      };

  export type WritersResolver =
    | ((
        parent: Episode,
        args: {},
        ctx: Context,
        info: GraphQLResolveInfo
      ) => Array<string | null> | Promise<Array<string | null>>)
    | {
        fragment: string;
        resolve: (
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>;
      };

  export interface Type {
    directors:
      | ((
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>)
      | {
          fragment: string;
          resolve: (
            parent: Episode,
            args: {},
            ctx: Context,
            info: GraphQLResolveInfo
          ) => Array<string | null> | Promise<Array<string | null>>;
        };

    guestStars:
      | ((
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>)
      | {
          fragment: string;
          resolve: (
            parent: Episode,
            args: {},
            ctx: Context,
            info: GraphQLResolveInfo
          ) => Array<string | null> | Promise<Array<string | null>>;
        };

    writers:
      | ((
          parent: Episode,
          args: {},
          ctx: Context,
          info: GraphQLResolveInfo
        ) => Array<string | null> | Promise<Array<string | null>>)
      | {
          fragment: string;
          resolve: (
            parent: Episode,
            args: {},
            ctx: Context,
            info: GraphQLResolveInfo
          ) => Array<string | null> | Promise<Array<string | null>>;
        };
  }
}

The following error is thrown

{
    "resource": "/Documents/workspace/GraphQL/tvdb-graphql/src/generated/test-resolvers/Episode.ts",
    "owner": "typescript",
    "code": "2322",
    "severity": 8,
    "message": "Type '{ directors: (parent: Episode) => string[] | null; guestStars: (parent: Episode) => string[] | null; writers: (parent: Episode) => string[] | null; }' is not assignable to type 'Type'.\n  Types of property 'directors' are incompatible.\n    Type '(parent: Episode) => string[] | null' is not assignable to type '((parent: Episode, args: {}, ctx: any, info: GraphQLResolveInfo) => (string | null)[] | Promise<(string | null)[]>) | { fragment: string; resolve: (parent: Episode, args: {}, ctx: any, info: GraphQLResolveInfo) => (string | null)[] | Promise<...>; }'.\n      Type '(parent: Episode) => string[] | null' is not assignable to type '(parent: Episode, args: {}, ctx: any, info: GraphQLResolveInfo) => (string | null)[] | Promise<(string | null)[]>'.\n        Type 'string[] | null' is not assignable to type '(string | null)[] | Promise<(string | null)[]>'.\n          Type 'null' is not assignable to type '(string | null)[] | Promise<(string | null)[]>'.",
    "source": "ts",
    "startLineNumber": 6,
    "startColumn": 14,
    "endLineNumber": 6,
    "endColumn": 21
}

• Graphqlgen version: 0.6.0-rc9
• OS name and version: MacOS Mojave