added signin button color experiment. closes #1306 (#1320)

app/experiments.js

@@ -1,6 +1,22 @@
 import hash from 'string-hash';
+import Account from './ui/account';
 
-const experiments = {};
+const experiments = {
+  signin_button_color: {
+    eligible: function() {
+      return true;
+    },
+    variant: function() {
+      return ['white-blue', 'blue', 'white-violet', 'violet'][
+        Math.floor(Math.random() * 4)
+      ];
+    },
+    run: function(variant, state) {
+      const account = state.cache(Account, 'account');
+      account.buttonClass = variant;
+    }
+  }
+};
 
 //Returns a number between 0 and 1
 // eslint-disable-next-line no-unused-vars
@@ -25,23 +41,12 @@ export default function initialize(state, emitter) {
       xp.run(+state.query.v, state, emitter);
     }
   });
-
-  if (!state.storage.get('testpilot_ga__cid')) {
-    // first ever visit. check again after cid is assigned.
-    emitter.on('DOMContentLoaded', () => {
-      checkExperiments(state, emitter);
-    });
+  const enrolled = state.storage.enrolled;
+  // single experiment per session for now
+  const id = Object.keys(enrolled)[0];
+  if (Object.keys(experiments).includes(id)) {
+    experiments[id].run(enrolled[id], state, emitter);
   } else {
-    const enrolled = state.storage.enrolled.filter(([id, variant]) => {
-      const xp = experiments[id];
-      if (xp) {
-        xp.run(variant, state, emitter);
-      }
-      return !!xp;
-    });
-    // single experiment per session for now
-    if (enrolled.length === 0) {
-      checkExperiments(state, emitter);
-    }
+    checkExperiments(state, emitter);
   }
 }