Remove identityState when deleting containers

Fixes #1140

src/js/background/assignManager.js

@@ -102,6 +102,7 @@ window.assignManager = {
     async deleteContainer(userContextId) {
       const sitesByContainer = await this.getAssignedSites(userContextId);
       this.area.remove(Object.keys(sitesByContainer));
+      identityState.storageArea.remove(backgroundLogic.cookieStoreId(userContextId));
     },
 
     async getAssignedSites(userContextId = null) {

test/issues/1140.test.js

@@ -0,0 +1,27 @@
+const { sinon, nextTick, buildBackgroundDom } = require("../common");
+
+describe("#1140", () => {
+  beforeEach(async () => {
+    this.background = await buildBackgroundDom();
+  });
+
+  describe("removing containers", () => {
+    beforeEach(async () => {
+      this.background.browser.contextualIdentities.onRemoved.addListener = sinon.stub();
+      const [promise] = this.background.browser.runtime.onMessage.addListener.yield({
+        method: "deleteContainer",
+        message: {
+          userContextId: "1"
+        }
+      });
+      await promise;
+      await nextTick();
+    });
+
+    it("should remove the identitystate from storage as well", async () => {
+      this.background.browser.storage.local.remove.should.have.been.calledWith([
+        "identitiesState@@_firefox-container-1"
+      ]);
+    });
+  });
+});