Introduce new composition printer / implementation

This forks from the newly updated schema printer. However, the goal
of this printer is to print the FINAL composition, rather than the
schema for a single federated service.

By peeking at the existing annotations in the `extensions` on the
composed `GraphQLSchema`, the composition printer can gather
important metadata like type and field ownership which is then
annotated in the final SDL.

packages/apollo-federation/src/service/__tests__/printComposedSdl.test.ts

@@ -0,0 +1,265 @@
+import { lexicographicSortSchema } from 'graphql';
+import { fixtures } from 'apollo-federation-integration-testsuite';
+import { composeAndValidate } from '../../composition';
+import { printComposedSdl } from '../printComposedSdl';
+
+describe('printComposedSdl', () => {
+  const { schema, errors } = composeAndValidate(fixtures);
+  const sorted = lexicographicSortSchema(schema);
+
+  it('composes without errors', () => {
+    expect(errors).toHaveLength(0);
+  });
+
+  it('prints a fully composed schema correctly', () => {
+    expect(printComposedSdl(sorted, fixtures)).toMatchInlineSnapshot(`
+      "schema
+        @graph(name: \\"accounts\\", url: \\"undefined\\")
+        @graph(name: \\"books\\", url: \\"undefined\\")
+        @graph(name: \\"documents\\", url: \\"undefined\\")
+        @graph(name: \\"inventory\\", url: \\"undefined\\")
+        @graph(name: \\"product\\", url: \\"undefined\\")
+        @graph(name: \\"reviews\\", url: \\"undefined\\")
+        @composedGraph(version: 1)
+      {
+        query: Query
+        mutation: Mutation
+      }
+
+      directive @stream on FIELD
+
+      directive @transform(from: String!) on FIELD
+
+      type Query {
+        body: Body! @resolve(graph: \\"documents\\")
+        book(isbn: String!): Book @resolve(graph: \\"books\\")
+        books: [Book] @resolve(graph: \\"books\\")
+        library(id: ID!): Library @resolve(graph: \\"books\\")
+        me: User @resolve(graph: \\"accounts\\")
+        product(upc: String!): Product @resolve(graph: \\"product\\")
+        topCars(first: Int = 5): [Car] @resolve(graph: \\"product\\")
+        topProducts(first: Int = 5): [Product] @resolve(graph: \\"product\\")
+        topReviews(first: Int = 5): [Review] @resolve(graph: \\"reviews\\")
+        user(id: ID!): User @resolve(graph: \\"accounts\\")
+        vehicle(id: String!): Vehicle @resolve(graph: \\"product\\")
+      }
+
+      union Body = Image | Text
+
+      type Image {
+        attributes: ImageAttributes!
+        name: String!
+      }
+
+      type ImageAttributes {
+        url: String!
+      }
+
+      type Text {
+        attributes: TextAttributes!
+        name: String!
+      }
+
+      type TextAttributes {
+        bold: Boolean
+        text: String
+      }
+
+      type Book implements Product
+        @owner(graph: \\"books\\")
+        @key(fields: \\"isbn\\", graph: \\"books\\")
+        @key(fields: \\"isbn\\", graph: \\"inventory\\")
+        @key(fields: \\"isbn\\", graph: \\"product\\")
+        @key(fields: \\"isbn\\", graph: \\"reviews\\")
+      {
+        details: ProductDetailsBook @resolve(graph: \\"product\\")
+        inStock: Boolean @resolve(graph: \\"inventory\\")
+        isbn: String!
+        isCheckedOut: Boolean @resolve(graph: \\"inventory\\")
+        metadata: [MetadataOrError]
+        name(delimeter: String = \\" \\"): String @resolve(graph: \\"product\\") @requires(fields: \\"title year\\")
+        price: String @resolve(graph: \\"product\\")
+        relatedReviews: [Review!]! @resolve(graph: \\"reviews\\") @requires(fields: \\"similarBooks { isbn }\\")
+        reviews: [Review] @resolve(graph: \\"reviews\\")
+        similarBooks: [Book]!
+        sku: String! @resolve(graph: \\"product\\")
+        title: String
+        upc: String! @resolve(graph: \\"product\\")
+        year: Int
+      }
+
+      interface Product {
+        details: ProductDetails
+        inStock: Boolean
+        name: String
+        price: String
+        reviews: [Review]
+        sku: String!
+        upc: String!
+      }
+
+      interface ProductDetails {
+        country: String
+      }
+
+      type Review
+        @owner(graph: \\"reviews\\")
+        @key(fields: \\"id\\", graph: \\"reviews\\")
+      {
+        author: User @provides(fields: \\"username\\")
+        body(format: Boolean = false): String
+        id: ID!
+        metadata: [MetadataOrError]
+        product: Product
+      }
+
+      type User
+        @owner(graph: \\"accounts\\")
+        @key(fields: \\"id\\", graph: \\"accounts\\")
+        @key(fields: \\"id\\", graph: \\"inventory\\")
+        @key(fields: \\"id\\", graph: \\"product\\")
+        @key(fields: \\"id\\", graph: \\"reviews\\")
+      {
+        account: AccountType
+        birthDate(locale: String): String
+        goodAddress: Boolean @resolve(graph: \\"reviews\\") @requires(fields: \\"metadata { address }\\")
+        goodDescription: Boolean @resolve(graph: \\"inventory\\") @requires(fields: \\"metadata { description }\\")
+        id: ID!
+        metadata: [UserMetadata]
+        name: String
+        numberOfReviews: Int! @resolve(graph: \\"reviews\\")
+        reviews: [Review] @resolve(graph: \\"reviews\\")
+        thing: Thing @resolve(graph: \\"product\\")
+        username: String
+        vehicle: Vehicle @resolve(graph: \\"product\\")
+      }
+
+      union AccountType = PasswordAccount | SMSAccount
+
+      type PasswordAccount
+        @owner(graph: \\"accounts\\")
+        @key(fields: \\"email\\", graph: \\"accounts\\")
+      {
+        email: String!
+      }
+
+      type SMSAccount
+        @owner(graph: \\"accounts\\")
+        @key(fields: \\"number\\", graph: \\"accounts\\")
+      {
+        number: String
+      }
+
+      type UserMetadata {
+        address: String
+        description: String
+        name: String
+      }
+
+      union Thing = Car | Ikea
+
+      type Car implements Vehicle
+        @owner(graph: \\"product\\")
+        @key(fields: \\"id\\", graph: \\"product\\")
+        @key(fields: \\"id\\", graph: \\"reviews\\")
+      {
+        description: String
+        id: String!
+        price: String
+        retailPrice: String @resolve(graph: \\"reviews\\") @requires(fields: \\"price\\")
+      }
+
+      interface Vehicle {
+        description: String
+        id: String!
+        price: String
+        retailPrice: String
+      }
+
+      type Ikea {
+        asile: Int
+      }
+
+      union MetadataOrError = Error | KeyValue
+
+      type Error {
+        code: Int
+        message: String
+      }
+
+      type KeyValue {
+        key: String!
+        value: String!
+      }
+
+      type ProductDetailsBook implements ProductDetails {
+        country: String
+        pages: Int
+      }
+
+      type Library
+        @owner(graph: \\"books\\")
+        @key(fields: \\"id\\", graph: \\"books\\")
+        @key(fields: \\"id\\", graph: \\"accounts\\")
+      {
+        id: ID!
+        name: String
+        userAccount(id: ID! = 1): User @resolve(graph: \\"accounts\\") @requires(fields: \\"name\\")
+      }
+
+      type Mutation {
+        deleteReview(id: ID!): Boolean @resolve(graph: \\"reviews\\")
+        login(password: String!, username: String!): User @resolve(graph: \\"accounts\\")
+        reviewProduct(body: String!, upc: String!): Product @resolve(graph: \\"reviews\\")
+        updateReview(review: UpdateReviewInput!): Review @resolve(graph: \\"reviews\\")
+      }
+
+      input UpdateReviewInput {
+        body: String
+        id: ID!
+      }
+
+      type Amazon {
+        referrer: String
+      }
+
+      union Brand = Amazon | Ikea
+
+      type Furniture implements Product
+        @owner(graph: \\"product\\")
+        @key(fields: \\"upc\\", graph: \\"product\\")
+        @key(fields: \\"sku\\", graph: \\"product\\")
+        @key(fields: \\"sku\\", graph: \\"inventory\\")
+        @key(fields: \\"upc\\", graph: \\"reviews\\")
+      {
+        brand: Brand
+        details: ProductDetailsFurniture
+        inStock: Boolean @resolve(graph: \\"inventory\\")
+        isHeavy: Boolean @resolve(graph: \\"inventory\\")
+        metadata: [MetadataOrError]
+        name: String
+        price: String
+        reviews: [Review] @resolve(graph: \\"reviews\\")
+        sku: String!
+        upc: String!
+      }
+
+      type ProductDetailsFurniture implements ProductDetails {
+        color: String
+        country: String
+      }
+
+      type Van implements Vehicle
+        @owner(graph: \\"product\\")
+        @key(fields: \\"id\\", graph: \\"product\\")
+        @key(fields: \\"id\\", graph: \\"reviews\\")
+      {
+        description: String
+        id: String!
+        price: String
+        retailPrice: String @resolve(graph: \\"reviews\\") @requires(fields: \\"price\\")
+      }
+      "
+    `);
+  });
+});