introspection: Add support for repeatable directives

src/type/__tests__/introspection-test.js

@@ -27,7 +27,10 @@ describe('Introspection', () => {
         },
       }),
     });
-    const source = getIntrospectionQuery({ descriptions: false });
+    const source = getIntrospectionQuery({
+      descriptions: false,
+      directiveIsRepeatable: true,
+    });
 
     const result = graphqlSync({ schema, source });
     expect(result).to.deep.equal({
@@ -648,6 +651,21 @@ describe('Introspection', () => {
                   isDeprecated: false,
                   deprecationReason: null,
                 },
+                {
+                  name: 'isRepeatable',
+                  args: [],
+                  type: {
+                    kind: 'NON_NULL',
+                    name: null,
+                    ofType: {
+                      kind: 'SCALAR',
+                      name: 'Boolean',
+                      ofType: null,
+                    },
+                  },
+                  isDeprecated: false,
+                  deprecationReason: null,
+                },
                 {
                   name: 'locations',
                   args: [],
@@ -809,6 +827,7 @@ describe('Introspection', () => {
           directives: [
             {
               name: 'include',
+              isRepeatable: false,
               locations: ['FIELD', 'FRAGMENT_SPREAD', 'INLINE_FRAGMENT'],
               args: [
                 {
@@ -828,6 +847,7 @@ describe('Introspection', () => {
             },
             {
               name: 'skip',
+              isRepeatable: false,
               locations: ['FIELD', 'FRAGMENT_SPREAD', 'INLINE_FRAGMENT'],
               args: [
                 {
@@ -847,6 +867,7 @@ describe('Introspection', () => {
             },
             {
               name: 'deprecated',
+              isRepeatable: false,
               locations: ['FIELD_DEFINITION', 'ENUM_VALUE'],
               args: [
                 {
@@ -1394,7 +1415,7 @@ describe('Introspection', () => {
     });
 
     const schema = new GraphQLSchema({ query: QueryRoot });
-    const source = getIntrospectionQuery();
+    const source = getIntrospectionQuery({ directiveIsRepeatable: true });
 
     /* istanbul ignore next */
     function fieldResolver(_1, _2, _3, info) {

src/type/introspection.js

@@ -89,6 +89,10 @@ export const __Directive = new GraphQLObjectType({
         type: GraphQLString,
         resolve: obj => obj.description,
       },
+      isRepeatable: {
+        type: GraphQLNonNull(GraphQLBoolean),
+        resolve: obj => obj.isRepeatable,
+      },
       locations: {
         type: GraphQLNonNull(GraphQLList(GraphQLNonNull(__DirectiveLocation))),
         resolve: obj => obj.locations,

src/utilities/__tests__/buildClientSchema-test.js

@@ -33,10 +33,12 @@ import { introspectionFromSchema } from '../introspectionFromSchema';
  * returns that schema printed as SDL.
  */
 function cycleIntrospection(sdlString: string): string {
+  const options = { directiveIsRepeatable: true };
+
   const serverSchema = buildSchema(sdlString);
-  const initialIntrospection = introspectionFromSchema(serverSchema);
+  const initialIntrospection = introspectionFromSchema(serverSchema, options);
   const clientSchema = buildClientSchema(initialIntrospection);
-  const secondIntrospection = introspectionFromSchema(clientSchema);
+  const secondIntrospection = introspectionFromSchema(clientSchema, options);
 
   /**
    * If the client then runs the introspection query against the client-side
@@ -457,7 +459,7 @@ describe('Type System: build schema from introspection', () => {
   it('builds a schema with custom directives', () => {
     const sdl = dedent`
       """This is a custom directive"""
-      directive @customDirective on FIELD
+      directive @customDirective repeatable on FIELD
 
       type Query {
         string: String

src/utilities/__tests__/getIntrospectionQuery-test.js

@@ -0,0 +1,32 @@
+// @flow strict
+
+import { expect } from 'chai';
+import { describe, it } from 'mocha';
+
+import { getIntrospectionQuery } from '../getIntrospectionQuery';
+
+describe('getIntrospectionQuery', () => {
+  it('skip all "description" fields', () => {
+    expect(getIntrospectionQuery()).to.match(/\bdescription\b/);
+
+    expect(getIntrospectionQuery({ descriptions: true })).to.match(
+      /\bdescription\b/,
+    );
+
+    expect(getIntrospectionQuery({ descriptions: false })).to.not.match(
+      /\bdescription\b/,
+    );
+  });
+
+  it('include "isRepeatable" field', () => {
+    expect(getIntrospectionQuery()).to.not.match(/\bisRepeatable\b/);
+
+    expect(getIntrospectionQuery({ directiveIsRepeatable: true })).to.match(
+      /\bisRepeatable\b/,
+    );
+
+    expect(
+      getIntrospectionQuery({ directiveIsRepeatable: false }),
+    ).to.not.match(/\bisRepeatable\b/);
+  });
+});

src/utilities/__tests__/schemaPrinter-test.js

@@ -740,6 +740,7 @@ describe('Type System Printer', () => {
       type __Directive {
         name: String!
         description: String
+        isRepeatable: Boolean!
         locations: [__DirectiveLocation!]!
         args: [__InputValue!]!
       }
@@ -927,6 +928,7 @@ describe('Type System Printer', () => {
       type __Directive {
         name: String!
         description: String
+        isRepeatable: Boolean!
         locations: [__DirectiveLocation!]!
         args: [__InputValue!]!
       }

src/utilities/buildClientSchema.js

@@ -385,6 +385,7 @@ export function buildClientSchema(
     return new GraphQLDirective({
       name: directiveIntrospection.name,
       description: directiveIntrospection.description,
+      isRepeatable: directiveIntrospection.isRepeatable,
       locations: directiveIntrospection.locations.slice(),
       args: buildInputValueDefMap(directiveIntrospection.args),
     });

src/utilities/getIntrospectionQuery.d.ts

@@ -5,6 +5,10 @@ export interface IntrospectionOptions {
   // Whether to include descriptions in the introspection result.
   // Default: true
   descriptions: boolean;
+
+  // Whether to include `isRepeatable` flag on directives.
+  // Default: false
+  directiveIsRepeatable?: boolean;
 }
 
 export function getIntrospectionQuery(options?: IntrospectionOptions): string;
@@ -167,6 +171,7 @@ export interface IntrospectionEnumValue {
 export interface IntrospectionDirective {
   readonly name: string;
   readonly description?: Maybe<string>;
+  readonly isRepeatable?: boolean;
   readonly locations: ReadonlyArray<DirectiveLocationEnum>;
   readonly args: ReadonlyArray<IntrospectionInputValue>;
 }

src/utilities/getIntrospectionQuery.js

@@ -5,11 +5,25 @@ import { type DirectiveLocationEnum } from '../language/directiveLocation';
 export type IntrospectionOptions = {|
   // Whether to include descriptions in the introspection result.
   // Default: true
-  descriptions: boolean,
+  descriptions?: boolean,
+
+  // Whether to include `isRepeatable` flag on directives.
+  // Default: false
+  directiveIsRepeatable?: boolean,
 |};
 
 export function getIntrospectionQuery(options?: IntrospectionOptions): string {
-  const descriptions = options?.descriptions !== false ? 'description' : '';
+  const optionsWithDefault = {
+    descriptions: true,
+    directiveIsRepeatable: false,
+    ...options,
+  };
+
+  const descriptions = optionsWithDefault.descriptions ? 'description' : '';
+  const directiveIsRepeatable = optionsWithDefault.directiveIsRepeatable
+    ? 'isRepeatable'
+    : '';
+
   return `
     query IntrospectionQuery {
       __schema {
@@ -22,6 +36,7 @@ export function getIntrospectionQuery(options?: IntrospectionOptions): string {
         directives {
           name
           ${descriptions}
+          ${directiveIsRepeatable}
           locations
           args {
             ...InputValue
@@ -259,6 +274,7 @@ export type IntrospectionEnumValue = {|
 export type IntrospectionDirective = {|
   +name: string,
   +description?: ?string,
+  +isRepeatable?: boolean,
   +locations: $ReadOnlyArray<DirectiveLocationEnum>,
   +args: $ReadOnlyArray<IntrospectionInputValue>,
 |};

src/utilities/introspectionFromSchema.js

@@ -26,7 +26,8 @@ export function introspectionFromSchema(
   schema: GraphQLSchema,
   options?: IntrospectionOptions,
 ): IntrospectionQuery {
-  const document = parse(getIntrospectionQuery(options));
+  const optionsWithDefaults = { directiveIsRepeatable: true, ...options };
+  const document = parse(getIntrospectionQuery(optionsWithDefaults));
   const result = execute({ schema, document });
   invariant(!isPromise(result) && !result.errors && result.data);
   return (result.data: any);