add defer directive type

Author: lilianammmatos

src/type/__tests__/introspection-test.js

@@ -865,6 +865,21 @@ describe('Introspection', () => {
                 },
               ],
             },
+            {
+              name: 'defer',
+              locations: ['FRAGMENT_SPREAD', 'INLINE_FRAGMENT'],
+              args: [
+                {
+                  defaultValue: null,
+                  name: 'if',
+                  type: {
+                    kind: 'SCALAR',
+                    name: 'Boolean',
+                    ofType: null,
+                  },
+                },
+              ],
+            },
             {
               name: 'deprecated',
               isRepeatable: false,

src/type/directives.js

@@ -170,6 +170,25 @@ export const GraphQLSkipDirective = new GraphQLDirective({
   },
 });
 
+/**
+ * Used to conditionally defer fragments.
+ */
+export const GraphQLDeferDirective = new GraphQLDirective({
+  name: 'defer',
+  description:
+    'Directs the executor to defer this fragment when the `if` argument is true or undefined.',
+  locations: [
+    DirectiveLocation.FRAGMENT_SPREAD,
+    DirectiveLocation.INLINE_FRAGMENT,
+  ],
+  args: {
+    if: {
+      type: GraphQLBoolean,
+      description: 'Defer fragment when true or undefined.',
+    },
+  },
+});
+
 /**
  * Constant string used for default reason for a deprecation.
  */
@@ -198,6 +217,7 @@ export const GraphQLDeprecatedDirective = new GraphQLDirective({
 export const specifiedDirectives = Object.freeze([
   GraphQLIncludeDirective,
   GraphQLSkipDirective,
+  GraphQLDeferDirective,
   GraphQLDeprecatedDirective,
 ]);
 

src/utilities/__tests__/findBreakingChanges-test.js

@@ -6,6 +6,7 @@ import { describe, it } from 'mocha';
 import { GraphQLSchema } from '../../type/schema';
 import {
   GraphQLSkipDirective,
+  GraphQLDeferDirective,
   GraphQLIncludeDirective,
   GraphQLDeprecatedDirective,
 } from '../../type/directives';
@@ -799,7 +800,11 @@ describe('findBreakingChanges', () => {
     const oldSchema = new GraphQLSchema({});
 
     const newSchema = new GraphQLSchema({
-      directives: [GraphQLSkipDirective, GraphQLIncludeDirective],
+      directives: [
+        GraphQLSkipDirective,
+        GraphQLIncludeDirective,
+        GraphQLDeferDirective,
+      ],
     });
 
     expect(findBreakingChanges(oldSchema, newSchema)).to.deep.equal([

src/utilities/__tests__/schemaPrinter-test.js

@@ -614,6 +614,14 @@ describe('Type System Printer', () => {
         if: Boolean!
       ) on FIELD | FRAGMENT_SPREAD | INLINE_FRAGMENT
 
+      """
+      Directs the executor to defer this fragment when the \`if\` argument is true or undefined.
+      """
+      directive @defer(
+        """Defer fragment when true or undefined."""
+        if: Boolean
+      ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+
       """Marks an element of a GraphQL schema as no longer supported."""
       directive @deprecated(
         """
@@ -921,6 +929,17 @@ describe('Type System Printer', () => {
         isDeprecated: Boolean!
         deprecationReason: String
       }
+      # Directs the executor to defer this fragment when the \`if\` argument is true or undefined.
+      directive @defer(
+        # Defer fragment when true or undefined.
+        if: Boolean
+      ) on FRAGMENT_SPREAD | INLINE_FRAGMENT
+
+      # Marks an element of a GraphQL schema as no longer supported.
+      directive @deprecated(
+        # Explains why this element was deprecated, usually also including a suggestion for how to access supported similar data. Formatted using the Markdown syntax, as specified by [CommonMark](https://commonmark.org/).
+        reason: String = "No longer supported"
+      ) on FIELD_DEFINITION | ENUM_VALUE
 
       # A Directive provides a way to describe alternate runtime execution and type validation behavior in a GraphQL document.
       #