Add null restriction to Enum value parser

Author: leebyron

src/executor/__tests__/variables.js

@@ -79,7 +79,7 @@ var TestType = new GraphQLObjectType({
 
 var schema = new GraphQLSchema({ query: TestType });
 
-describe('Execute: Handles input objects', () => {
+describe('Execute: Handles inputs', () => {
 
   describe('Handles objects and nullability', () => {
     describe('using inline structs', () => {
@@ -116,7 +116,7 @@ describe('Execute: Handles input objects', () => {
 
     describe('using variables', () => {
       var doc = `
-        query q($input:TestInputObject) {
+        query q($input: TestInputObject) {
           fieldWithObjectInput(input: $input)
         }
       `;
@@ -242,21 +242,6 @@ describe('Execute: Handles input objects', () => {
       });
     });
 
-    it('allows nullable inputs to be set to null directly', async () => {
-      var doc = `
-      {
-        fieldWithNullableStringInput(input: null)
-      }
-      `;
-      var ast = parse(doc);
-
-      return expect(await execute(schema, null, ast)).to.deep.equal({
-        data: {
-          fieldWithNullableStringInput: 'null'
-        }
-      });
-    });
-
     it('allows nullable inputs to be set to a value in a variable', async () => {
       var doc = `
       query SetsNullable($value: String) {

src/language/__tests__/parser.js

@@ -104,6 +104,12 @@ fragment MissingOn Type
     ).to.throw('Syntax Error GraphQL (1:9) Expected Name, found }');
   });
 
+  it('does not allow null as value', async () => {
+    expect(
+      () => parse('{ fieldWithNullableStringInput(input: null) }')
+    ).to.throw('Syntax Error GraphQL (1:39) Unexpected Name "null"');
+  });
+
   var kitchenSink = readFileSync(
     join(__dirname, '/kitchen-sink.graphql'),
     { encoding: 'utf8' }

src/language/parser.js

@@ -501,21 +501,22 @@ function parseValue(parser, isConst: boolean): Value {
         loc: loc(parser, token.start)
       };
     case TokenKind.NAME:
-      advance(parser);
-      switch (token.value) {
-        case 'true':
-        case 'false':
-          return {
-            kind: BOOLEAN,
-            value: token.value === 'true',
-            loc: loc(parser, token.start)
-          };
+      if (token.value === 'true' || token.value === 'false') {
+        advance(parser);
+        return {
+          kind: BOOLEAN,
+          value: token.value === 'true',
+          loc: loc(parser, token.start)
+        };
+      } else if (token.value !== 'null') {
+        advance(parser);
+        return {
+          kind: ENUM,
+          value: token.value,
+          loc: loc(parser, token.start)
+        };
       }
-      return {
-        kind: ENUM,
-        value: token.value,
-        loc: loc(parser, token.start)
-      };
+      break;
     case TokenKind.DOLLAR:
       if (!isConst) {
         return parseVariable(parser);