Add RelaySelector helper class, start of updated Environment interface

Summary:
Defines the `Selector` interface and implements helpers for converting fragment
props into Selectors. This is a building block for implementing
`FragmentSpecResolver` that will be the foundation of the new container APIs.

As part of making the test work I had to fix an issue with `BabelPluginGraphQL`.
It outputs a root fragment for a query, but this conflicted because the test
schema uses the name "Root" for the query type instead of the defacto standard
"Query". This then necessitated a fix to our validation of the `node` field,
which needed to check that the `node` field was not on the query type.

Reviewed By: wincent

Differential Revision: D4309955

fbshipit-source-id: e97c767dcb37974d3359165f011ff0fe63f87304

scripts/babel-relay-plugin/lib/HASH

@@ -1 +1 @@
-rmZo763xq6oGqjdkqeGl1CqgLvU=
+SzFLdHGEENZur/dboJUZxgpY5zU=

scripts/babel-relay-plugin/lib/RelayQLAST.js

@@ -664,6 +664,11 @@ var RelayQLType = function () {
     value: function isNonNull() {
       return this.isNonNullType;
     }
+  }, {
+    key: 'isQueryType',
+    value: function isQueryType() {
+      return this.schemaUnmodifiedType === this.context.schema.getQueryType();
+    }
   }, {
     key: 'isConnection',
     value: function isConnection() {

scripts/babel-relay-plugin/lib/RelayQLPrinter.js

@@ -601,7 +601,7 @@ module.exports = function (t, options) {
     if (field.getName() === 'node') {
       var argTypes = field.getDeclaredArguments();
       var argNames = Object.keys(argTypes);
-      if (argNames.length === 1 && argNames[0] === ID) {
+      if (!parentType.isQueryType() && argNames.length === 1 && argNames[0] === ID) {
         throw new RelayTransformError(util.format('You defined a `node(%s: %s)` field on type `%s`, but Relay requires ' + 'the `node` field to be defined on the root type. See the Object ' + 'Identification Guide: \n' + 'http://facebook.github.io/relay/docs/graphql-object-identification.html', ID, argNames[0] && argTypes[argNames[0]].getName({ modifiers: true }), parentType.getName({ modifiers: false })), field.getLocation());
       }
     }

scripts/babel-relay-plugin/src/RelayQLAST.js

@@ -640,6 +640,10 @@ class RelayQLType {
     return this.isNonNullType;
   }
 
+  isQueryType(): boolean {
+    return this.schemaUnmodifiedType === this.context.schema.getQueryType();
+  }
+
   isConnection(): boolean {
     if (!/Connection$/.test(this.getName({modifiers: false}))) {
       return false;
@@ -816,7 +820,7 @@ class RelayQLArgumentType {
       this.schemaUnmodifiedArgType === GraphQLID ||
       this.schemaUnmodifiedArgType === GraphQLInt ||
       this.schemaUnmodifiedArgType === GraphQLString
-    )
+    );
   }
 
   isEnum(): boolean {

scripts/babel-relay-plugin/src/RelayQLPrinter.js

@@ -743,7 +743,11 @@ module.exports = function(t: any, options: PrinterOptions): Function {
     if (field.getName() === 'node') {
       var argTypes = field.getDeclaredArguments();
       var argNames = Object.keys(argTypes);
-      if (argNames.length === 1 && argNames[0] === ID) {
+      if (
+        !parentType.isQueryType() &&
+        argNames.length === 1 &&
+        argNames[0] === ID
+      ) {
         throw new RelayTransformError(
           util.format(
             'You defined a `node(%s: %s)` field on type `%s`, but Relay requires ' +

scripts/jest/testschema.graphql

@@ -1,10 +1,10 @@
 schema {
-  query: Root
+  query: Query
   mutation: Mutation
   subscription: Subscription
 }
 
-type Root {
+type Query {
   checkinSearchQuery(query: CheckinSearchInput): CheckinSearchResult
   defaultSettings: Settings,
   route(waypoints: [WayPoint!]!): Route

src/environment/RelayEnvironmentTypes.js

@@ -0,0 +1,45 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule RelayEnvironmentTypes
+ * @flow
+ */
+
+'use strict';
+
+import type {
+  ConcreteFragmentDefinition,
+} from 'ConcreteQuery';
+import type {DataID} from 'RelayInternalTypes';
+import type RelayQuery from 'RelayQuery';
+import type {Variables} from 'RelayTypes';
+
+/**
+ * A selector defines the starting point for a traversal into the graph for the
+ * purposes of targeting a subgraph.
+ */
+export type Selector = {
+  dataID: DataID,
+  node: ConcreteFragmentDefinition,
+  variables: Variables,
+};
+
+/**
+ * An operation selector describes a specific instance of a GraphQL operation
+ * with variables applied.
+ *
+ * - `fragment`: a selector intended for use in reading or subscribing to
+ *   the results of the the operation.
+ * - `queries`: an object of queries that can be used to fetch the data for this
+ *   operation.
+ */
+export type OperationSelector = {
+  fragment: Selector,
+  queries: Array<RelayQuery.Root>,
+  variables: Variables,
+};