Simplify extension test

src/__tests__/http-test.js

@@ -2111,24 +2111,16 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
       it('allows for adding extensions', async () => {
         const app = server();
 
-        const extensions = ({ context = {} }) => {
-          if (context !== null && typeof context.startTime === 'number') {
-            return {
-              runTime: 1000000010 /* Date.now() */ - context.startTime,
-            };
-          }
-
-          return {};
-        };
-
         get(
           app,
           urlString(),
           graphqlHTTP(() => {
             return {
               schema: TestSchema,
-              context: { startTime: 1000000000 },
-              extensions,
+              context: { foo: 'bar' },
+              extensions({ context }) {
+                return { contextValue: JSON.stringify(context) };
+              },
             };
           }),
         );
@@ -2140,7 +2132,7 @@ function urlString(urlParams?: ?{ [param: string]: mixed, ... }) {
         expect(response.status).to.equal(200);
         expect(response.type).to.equal('application/json');
         expect(response.text).to.equal(
-          '{"data":{"test":"Hello World"},"extensions":{"runTime":10}}',
+          '{"data":{"test":"Hello World"},"extensions":{"contextValue":"{\\"foo\\":\\"bar\\"}"}}',
         );
       });