feat: set returning user cookie (#312)

Set returning user cookie to measure exit rate for A/B test.

src/data/utils/cookies.js

@@ -1,14 +1,21 @@
 import Cookies from 'universal-cookie';
 import { getConfig } from '@edx/frontend-platform';
 
+export function setCookie(cookieName, cookieValue, cookieExpiry) {
+  const cookies = new Cookies();
+  const options = { domain: getConfig().COOKIE_DOMAIN, path: '/' };
+  if (cookieExpiry) {
+    options.expires = cookieExpiry;
+  }
+  cookies.set(cookieName, cookieValue, options);
+}
+
 export default function setSurveyCookie(surveyType) {
   const cookieName = getConfig().USER_SURVEY_COOKIE_NAME;
   if (cookieName) {
-    const cookies = new Cookies();
     const signupTimestamp = (new Date()).getTime();
     // set expiry to exactly 24 hours from now
     const cookieExpiry = new Date(signupTimestamp + 1 * 864e5);
-    const options = { domain: getConfig().COOKIE_DOMAIN, expires: cookieExpiry, path: '/' };
-    cookies.set(cookieName, surveyType, options);
+    setCookie(cookieName, surveyType, cookieExpiry);
   }
 }

src/data/utils/index.js

@@ -8,4 +8,4 @@ export {
   windowScrollTo,
 } from './dataUtils';
 export { default as AsyncActionType } from './reduxUtils';
-export { default as setSurveyCookie } from './cookies';
+export { default as setSurveyCookie, setCookie } from './cookies';