diff --git a/src/js/.eslintrc.js b/src/js/.eslintrc.js
index f78079f..11cd71a 100644
--- a/src/js/.eslintrc.js
+++ b/src/js/.eslintrc.js
@@ -7,6 +7,7 @@ module.exports = {
     "badge": true,
     "backgroundLogic": true,
     "identityState": true,
-    "messageHandler": true
+    "messageHandler": true,
+    "sync": true
   }
 };
diff --git a/src/js/background/assignManager.js b/src/js/background/assignManager.js
index 5c3f33e..8e82678 100644
--- a/src/js/background/assignManager.js
+++ b/src/js/background/assignManager.js
@@ -66,6 +66,7 @@ const assignManager = {
           this.setExempted(pageUrlorUrlKey, tabId);
         });
       }
+      // eslint-disable-next-line require-atomic-updates
       data.identityMacAddonUUID =
         await identityState.lookupMACaddonUUID(data.userContextId);
       await this.area.set({
@@ -124,7 +125,7 @@ const assignManager = {
       for(const configKey of Object.keys(macConfigs)) {
         if (configKey.includes("siteContainerMap@@_")) {
           const cookieStoreId = 
-            "firefox-container-" + macConfigs[configKey].userContextId;
+            "firefox-container-" + macConfigs[configKey].userContextId; 
           const match = identitiesList.find(
             localIdentity => localIdentity.cookieStoreId === cookieStoreId
           );
diff --git a/src/js/background/index.html b/src/js/background/index.html
index 78dbe21..c5c7889 100644
--- a/src/js/background/index.html
+++ b/src/js/background/index.html
@@ -14,11 +14,11 @@
     ]
 -->
     <script type="text/javascript" src="backgroundLogic.js"></script>
+    <script type="text/javascript" src="sync.js"></script>
     <script type="text/javascript" src="assignManager.js"></script>
     <script type="text/javascript" src="badge.js"></script>
     <script type="text/javascript" src="identityState.js"></script>
     <script type="text/javascript" src="messageHandler.js"></script>
-    <script type="text/javascript" src="sync.js"></script>
     <script type="text/javascript" src="test.js"></script>
   </body>
 </html>
diff --git a/src/js/background/sync.js b/src/js/background/sync.js
index f4959eb..48a6270 100644
--- a/src/js/background/sync.js
+++ b/src/js/background/sync.js
@@ -160,10 +160,10 @@ const sync = {
         sync.storageArea.onChangedListener
       );
 
-    const hasCIListener = await hasContextualIdentityListeners();
+    const hasCIListener = await sync.hasContextualIdentityListeners();
 
     if (!hasCIListener) {
-      await addContextualIdentityListeners();
+      await sync.addContextualIdentityListeners();
     }
 
     if (!hasStorageListener) {
@@ -178,10 +178,10 @@ const sync = {
         sync.storageArea.onChangedListener
       );
 
-    const hasCIListener = await hasContextualIdentityListeners();
+    const hasCIListener = await sync.hasContextualIdentityListeners();
             
     if (hasCIListener) {
-      await removeContextualIdentityListeners();
+      await sync.removeContextualIdentityListeners();
     }
 
     if (hasStorageListener) {
@@ -210,6 +210,30 @@ const sync = {
     await sync.storageArea.backup();
     return;  
   },
+
+  async addContextualIdentityListeners(listenerList) {
+    if(!listenerList) listenerList = syncCIListenerList;
+    await browser.contextualIdentities.onCreated.addListener(listenerList[0]);
+    await browser.contextualIdentities.onRemoved.addListener(listenerList[1]);
+    await browser.contextualIdentities.onUpdated.addListener(listenerList[2]);
+  },
+
+  async removeContextualIdentityListeners(listenerList) {
+    if(!listenerList) listenerList = syncCIListenerList;
+    await browser.contextualIdentities.onCreated.removeListener(listenerList[0]);
+    await browser.contextualIdentities.onRemoved.removeListener(listenerList[1]);
+    await browser.contextualIdentities.onUpdated.removeListener(listenerList[2]);
+  },
+
+  async hasContextualIdentityListeners(listenerList) {
+    if(!listenerList) listenerList = syncCIListenerList;
+    return (
+      await browser.contextualIdentities.onCreated.hasListener(listenerList[0]) &&
+      await browser.contextualIdentities.onRemoved.hasListener(listenerList[1]) &&
+      await browser.contextualIdentities.onUpdated.hasListener(listenerList[2])
+    );
+  }
+
 };
 
 sync.init();
@@ -381,7 +405,7 @@ async function reconcileSiteAssignments() {
   const deletedSiteList = 
     await sync.storageArea.getDeletedSiteList();
   for(const siteStoreKey of deletedSiteList) {
-    if (assignedSitesLocal.hasOwnProperty(siteStoreKey)) {
+    if (Object.prototype.hasOwnProperty.call(assignedSitesLocal,siteStoreKey)) {
       assignManager
         .storageArea
         .remove(siteStoreKey.replace(/^siteContainerMap@@_/, "https://"));
@@ -416,6 +440,7 @@ async function setAssignmentWithUUID (assignedSite, urlKey) {
   const uuid = assignedSite.identityMacAddonUUID;
   const cookieStoreId = await identityState.lookupCookieStoreId(uuid);
   if (cookieStoreId) {
+    // eslint-disable-next-line require-atomic-updates
     assignedSite.userContextId = cookieStoreId
       .replace(/^firefox-container-/, "");
     await assignManager.storageArea.set(
@@ -434,26 +459,3 @@ const syncCIListenerList = [
   sync.storageArea.addToDeletedList, 
   sync.storageArea.backup
 ];
-
-async function addContextualIdentityListeners(listenerList) {
-  if(!listenerList) listenerList = syncCIListenerList;
-  await browser.contextualIdentities.onCreated.addListener(listenerList[0]);
-  await browser.contextualIdentities.onRemoved.addListener(listenerList[1]);
-  await browser.contextualIdentities.onUpdated.addListener(listenerList[2]);
-}
-
-async function removeContextualIdentityListeners(listenerList) {
-  if(!listenerList) listenerList = syncCIListenerList;
-  await browser.contextualIdentities.onCreated.removeListener(listenerList[0]);
-  await browser.contextualIdentities.onRemoved.removeListener(listenerList[1]);
-  await browser.contextualIdentities.onUpdated.removeListener(listenerList[2]);
-}
-
-async function hasContextualIdentityListeners(listenerList) {
-  if(!listenerList) listenerList = syncCIListenerList;
-  return (
-    await browser.contextualIdentities.onCreated.hasListener(listenerList[0]) &&
-    await browser.contextualIdentities.onRemoved.hasListener(listenerList[1]) &&
-    await browser.contextualIdentities.onUpdated.hasListener(listenerList[2])
-  );
-}
diff --git a/src/js/background/test.js b/src/js/background/test.js
index 0f1c58f..166d0e8 100644
--- a/src/js/background/test.js
+++ b/src/js/background/test.js
@@ -365,12 +365,12 @@ browser.tests = {
 
   async stopSyncListeners() {
     await browser.storage.onChanged.removeListener(sync.storageArea.onChangedListener);
-    await removeContextualIdentityListeners();
+    await sync.removeContextualIdentityListeners();
   },
 
   async startListeners() {
     await browser.storage.onChanged.addListener(sync.storageArea.onChangedListener);
-    await addContextualIdentityListeners();
+    await sync.addContextualIdentityListeners();
   },
 
 };
diff --git a/test/features/external-webextensions.test.js b/test/features/external-webextensions.test.js
index 485005c..76db303 100644
--- a/test/features/external-webextensions.test.js
+++ b/test/features/external-webextensions.test.js
@@ -27,7 +27,9 @@ describe("External Webextensions", () => {
       const answer = await promise;
       expect(answer.userContextId === "1").to.be.true;
       expect(answer.neverAsk === false).to.be.true;
-      expect(answer.hasOwnProperty("identityMacAddonUUID")).to.be.true;
+      expect(
+        Object.prototype.hasOwnProperty.call(
+          answer, "identityMacAddonUUID")).to.be.true;
     });
   });
 
diff --git a/test/features/sync.test.js b/test/features/sync.test.js
index 72656fa..61915e1 100644
--- a/test/features/sync.test.js
+++ b/test/features/sync.test.js
@@ -1,7 +1,6 @@
 describe("Sync", () => {
 
   it("should init sync on startup", async () => {
-    console.log("!!!a")
     const tab = await helper.browser.initializeWithTab();
     console.log(await background.browser.storage.local.get());
     const mozContainer = await background.browser.contextualIdentities.create({
@@ -54,7 +53,6 @@ describe("Sync", () => {
         });
       }
     }));
-    console.log("!!!c");
     await background.browser.runtime.onStartup.addListener.yield();
     await nextTick();
 
@@ -62,7 +60,6 @@ describe("Sync", () => {
     console.log(await background.browser.storage.local.get());
 
     expect(sync.identities.length).to.equal(5);
-    console.log("!!!b");
   });
 
 });
\ No newline at end of file