Adds Unique Directives Validation Rule.

This implements graphql/graphql-spec#229, in order to adhere with the October2016 edition of the spec.

src/validation/__tests__/UniqueDirectivesPerLocation-test.js

@@ -0,0 +1,111 @@
+/**
+ *  Copyright (c) 2015, 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.
+ */
+
+import { describe, it } from 'mocha';
+import { expectPassesRule, expectFailsRule } from './harness';
+import {
+  UniqueDirectivesPerLocation,
+  duplicateDirectiveMessage,
+} from '../rules/UniqueDirectivesPerLocation';
+
+
+function duplicateDirective(directiveName, l1, c1, l2, c2) {
+  return {
+    message: duplicateDirectiveMessage(directiveName),
+    locations: [ { line: l1, column: c1 }, { line: l2, column: c2 } ],
+  };
+}
+
+describe('Validate: Directives Are Unique Per Location', () => {
+
+  it('no directives', () => {
+    expectPassesRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type {
+        field
+      }
+    `);
+  });
+
+  it('unique directives in different locations', () => {
+    expectPassesRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type @directiveA {
+        field @directiveB
+      }
+    `);
+  });
+
+  it('unique directives in same locations', () => {
+    expectPassesRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type @directiveA @directiveB {
+        field @directiveA @directiveB
+      }
+    `);
+  });
+
+  it('same directives in different locations', () => {
+    expectPassesRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type @directiveA {
+        field @directiveA
+      }
+    `);
+  });
+
+  it('same directives in similar locations', () => {
+    expectPassesRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type {
+        field @directive
+        field @directive
+      }
+    `);
+  });
+
+  it('duplicate directives in one location', () => {
+    expectFailsRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type {
+        field @directive @directive
+      }
+    `, [
+      duplicateDirective('directive', 3, 15, 3, 26)
+    ]);
+  });
+
+  it('many duplicate directives in one location', () => {
+    expectFailsRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type {
+        field @directive @directive @directive
+      }
+    `, [
+      duplicateDirective('directive', 3, 15, 3, 26),
+      duplicateDirective('directive', 3, 15, 3, 37)
+    ]);
+  });
+
+  it('different duplicate directives in one location', () => {
+    expectFailsRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type {
+        field @directiveA @directiveB @directiveA @directiveB
+      }
+    `, [
+      duplicateDirective('directiveA', 3, 15, 3, 39),
+      duplicateDirective('directiveB', 3, 27, 3, 51)
+    ]);
+  });
+
+  it('duplicate directives in many locations', () => {
+    expectFailsRule(UniqueDirectivesPerLocation, `
+      fragment Test on Type @directive @directive {
+        field @directive @directive
+      }
+    `, [
+      duplicateDirective('directive', 2, 29, 2, 40),
+      duplicateDirective('directive', 3, 15, 3, 26)
+    ]);
+  });
+
+});

src/validation/rules/UniqueDirectivesPerLocation.js

@@ -0,0 +1,48 @@
+/* @flow */
+/**
+ *  Copyright (c) 2015, 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.
+ */
+
+import type { ValidationContext } from '../index';
+import { GraphQLError } from '../../error';
+
+
+export function duplicateDirectiveMessage(directiveName: string): string {
+  return `The directive "${directiveName}" can only be used once at ` +
+    'this location.';
+}
+
+/**
+ * Unique directive names per location
+ *
+ * A GraphQL document is only valid if all directives at a given location
+ * are uniquely named.
+ */
+export function UniqueDirectivesPerLocation(context: ValidationContext): any {
+  return {
+    // Many different AST nodes may contain directives. Rather than listing
+    // them all, just listen for entering any node, and check to see if it
+    // defines any directives.
+    enter(node) {
+      if (node.directives) {
+        const knownDirectives = Object.create(null);
+        node.directives.forEach(directive => {
+          const directiveName = directive.name.value;
+          if (knownDirectives[directiveName]) {
+            context.reportError(new GraphQLError(
+              duplicateDirectiveMessage(directiveName),
+              [ knownDirectives[directiveName], directive ]
+            ));
+          } else {
+            knownDirectives[directiveName] = directive;
+          }
+        });
+      }
+    }
+  };
+}

src/validation/specifiedRules.js

@@ -56,6 +56,11 @@ import { NoUnusedVariables } from './rules/NoUnusedVariables';
 // Spec Section: "Directives Are Defined"
 import { KnownDirectives } from './rules/KnownDirectives';
 
+// Spec Section: "Directives Are Unique Per Location"
+import {
+  UniqueDirectivesPerLocation
+} from './rules/UniqueDirectivesPerLocation';
+
 // Spec Section: "Argument Names"
 import { KnownArgumentNames } from './rules/KnownArgumentNames';
 
@@ -104,6 +109,7 @@ export const specifiedRules: Array<(context: ValidationContext) => any> = [
   NoUndefinedVariables,
   NoUnusedVariables,
   KnownDirectives,
+  UniqueDirectivesPerLocation,
   KnownArgumentNames,
   UniqueArgumentNames,
   ArgumentsOfCorrectType,