From b013e73084c7c012527a3d44f215f46d1f8465ae Mon Sep 17 00:00:00 2001
From: Lee Byron <lee@leebyron.com>
Date: Fri, 28 Apr 2017 18:53:25 -0700
Subject: [PATCH] Allow for nullish values when defining enums

Fixes #832
---
 src/type/__tests__/definition-test.js | 27 +++++++++++++++++++++++++++
 src/type/definition.js                |  3 +--
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/src/type/__tests__/definition-test.js b/src/type/__tests__/definition-test.js
index b23a2257bb..1eff90137a 100644
--- a/src/type/__tests__/definition-test.js
+++ b/src/type/__tests__/definition-test.js
@@ -184,6 +184,33 @@ describe('Type System: Example', () => {
     });
   });
 
+  it('defines an enum type with a value of `null` and `undefined`', () => {
+    const EnumTypeWithNullishValue = new GraphQLEnumType({
+      name: 'EnumWithNullishValue',
+      values: {
+        NULL: { value: null },
+        UNDEFINED: { value: undefined },
+      }
+    });
+
+    expect(EnumTypeWithNullishValue.getValues()).to.deep.equal([
+      {
+        name: 'NULL',
+        description: undefined,
+        isDeprecated: false,
+        deprecationReason: undefined,
+        value: null,
+      },
+      {
+        name: 'UNDEFINED',
+        description: undefined,
+        isDeprecated: false,
+        deprecationReason: undefined,
+        value: undefined,
+      },
+    ]);
+  });
+
   it('defines an object type with deprecated field', () => {
     const TypeWithDeprecatedField = new GraphQLObjectType({
       name: 'foo',
diff --git a/src/type/definition.js b/src/type/definition.js
index 9fd9a459d1..1e79aeeced 100644
--- a/src/type/definition.js
+++ b/src/type/definition.js
@@ -9,7 +9,6 @@
  */
 
 import invariant from '../jsutils/invariant';
-import isNullish from '../jsutils/isNullish';
 import { ENUM } from '../language/kinds';
 import { assertValidName } from '../utilities/assertValidName';
 import type {
@@ -984,7 +983,7 @@ function defineEnumValues(
       description: value.description,
       isDeprecated: Boolean(value.deprecationReason),
       deprecationReason: value.deprecationReason,
-      value: isNullish(value.value) ? valueName : value.value,
+      value: value.hasOwnProperty('value') ? value.value : valueName,
     };
   });
 }