Finish repo_tabs_spec

spec/javascripts/repo/repo_tabs_spec.js

 import Vue from 'vue';
+import RepoStore from '~/repo/repo_store';
 import repoTabs from '~/repo/repo_tabs.vue';
 
-describe('RepoTabss', () => {
-  const RepoTabs = Vue.extend(repoTabs);
-
+describe('RepoTabs', () => {
+  const openedFiles = [{
+    id: 0,
+    active: true,
+  }, {
+    id: 1,
+  }];
   function createComponent() {
+    const RepoTabs = Vue.extend(repoTabs);
+
     return new RepoTabs().$mount();
   }
 
+  beforeEach(() => {
+    spyOn(repoTabs.methods, 'isOverflow');
+  });
+
   it('renders a list of tabs', () => {
+    RepoStore.openedFiles = openedFiles;
+    RepoStore.tabsOverflow = true;
+
+    const vm = createComponent();
+    const tabs = [...vm.$el.querySelectorAll(':scope > li')];
+
+    expect(vm.$el.id).toEqual('tabs');
+    expect(vm.$el.classList.contains('overflown')).toBeTruthy();
+    expect(tabs.length).toEqual(2);
+    expect(tabs[0].classList.contains('active')).toBeTruthy();
+    expect(tabs[1].classList.contains('active')).toBeFalsy();
   });
 
-  it('does not render a tabs list if no isMini', () => {
+  it('does not render a tabs list if not isMini', () => {
+    RepoStore.openedFiles = [];
+
+    const vm = createComponent();
+
+    expect(vm.$el.innerHTML).toBeFalsy();
+  });
+
+  it('does not apply overflown class if not tabsOverflow', () => {
+    RepoStore.openedFiles = openedFiles;
+    RepoStore.tabsOverflow = false;
+
+    const vm = createComponent();
+
+    expect(vm.$el.classList.contains('overflown')).toBeFalsy();
   });
 });