fix parsing of scalar

src/graphql/UniversalDateTimeScalar.test.ts

@@ -4,7 +4,7 @@ import utc from 'dayjs/plugin/utc'
 import { GraphQLError } from 'graphql/error'
 import { Kind } from 'graphql/language'
 
-import { UniversalDateTime } from './UniversalDateTimeScalar'
+import { UniversalDateTime, isValidDayjs } from './UniversalDateTimeScalar'
 
 dayjs.extend(utc)
 dayjs.extend(timezone)
@@ -85,4 +85,12 @@ describe('UniversalDateTime', () => {
 
     expect(date).toBe(expected)
   })
+
+  test('parseLiteral should return dayjs', () => {
+    const expected = '2019-11-01T11:00:00Z'
+    const date = parseLiteral({ value: expected, kind: Kind.STRING }, {}) as dayjs.Dayjs
+
+    expect(date.valueOf()).toBe(new Date(expected).valueOf())
+    expect(date.isValid()).toBe(true)
+  })
 })

src/graphql/UniversalDateTimeScalar.ts

@@ -59,7 +59,7 @@ export const UniversalDateTime = new GraphQLScalarType({
     if (typeof ast.value === 'string' && isValidDateString(ast.value)) {
       return ast.value
     } if (isValidDayjs(ast.value)) {
-      return ast.value
+      return stringToDayjs(ast.value)
     }
     throw new GraphQLError(`Require string on format YYYY-MM-DD or iso8601/dayjs valid string, found: ${ast.value}`)
   },