Add method to clear mutation listeners in RPC client

lib/realm.js

@@ -125,7 +125,10 @@ Object.defineProperties(Realm, {
         set: util.setterForProperty('defaultPath'),
     },
     clearTestState: {
-        value: rpc.clearTestState,
+        value: function() {
+            util.clearMutationListeners();
+            rpc.clearTestState();
+        },
     },
 });
 

lib/util.js

@@ -8,9 +8,10 @@ const constants = require('./constants');
 const rpc = require('./rpc');
 
 const {keys} = constants;
-const mutationListeners = {};
+let mutationListeners = {};
 
 module.exports = {
+    clearMutationListeners,
     fireMutationListeners,
     createList,
     createMethods,
@@ -31,6 +32,10 @@ function removeMutationListener(realmId, callback) {
     }
 }
 
+function clearMutationListeners() {
+    mutationListeners = {};
+}
+
 function fireMutationListeners(realmId) {
     let listeners = mutationListeners[realmId];
     if (listeners) {