Detect unresolvable fields in object types implementing the interface

[kamilkisiela]

We've got a case like this:

A

extend schema @link(url: "https://specs.apollo.dev/federation/v2.3", import: ["@key"])

interface Post {
  id: ID!
  createdAt: String!
}

type ImagePost implements Post @key(fields: "id") {
  id: ID!
  createdAt: String!
}

type Query {
  feed: [Post]
}

B

extend schema
  @link(
    url: "https://specs.apollo.dev/federation/v2.3"
    import: ["@key", "@shareable", "@override"]
  )

interface Post {
  id: ID!
  createdAt: String!
}

type TextPost implements Post @key(fields: "id") {
  id: ID!
  createdAt: String!
  body: String!
}

interface AnotherPost {
  id: ID!
  createdAt: String!
}

type ImagePost implements AnotherPost @key(fields: "id") {
  id: ID!
  createdAt: String! @override(from: "a") # it makes the ImagePost.createdAt in A unresolvable
}

Currently the query planner is not aware of ImagePost.createdAt being not resolvable in subgraph A. It probably only looks at the interface field and its availability in subgraphs.

There's another case but with @external annotation used in place of @override.

Once we push a fix, it should cover both scenarios.