Added repo_tab spec

spec/javascripts/repo/repo_tab_spec.js

+import Vue from 'vue';
+import repoTab from '~/repo/repo_tab.vue';
+
+describe('RepoTab', () => {
+  const RepoTab = Vue.extend(repoTab);
+
+  function createComponent(propsData) {
+    return new RepoTab({
+      propsData,
+    }).$mount();
+  }
+
+  it('renders a close link and a name link', () => {
+    const tab = {
+      loading: false,
+      url: 'url',
+      name: 'name',
+    };
+    const vm = createComponent({
+      tab,
+    });
+    const close = vm.$el.querySelector('.close');
+    const name = vm.$el.querySelector(`a[title="${tab.url}"]`)
+
+    spyOn(vm, 'xClicked');
+    spyOn(vm, 'tabClicked');
+
+    expect(close).toBeTruthy();
+    expect(close.querySelector('.fa-times')).toBeTruthy();
+    expect(name).toBeTruthy();
+    expect(name.textContent).toEqual(tab.name);
+
+    close.click();
+    name.click();
+
+    expect(vm.xClicked).toHaveBeenCalledWith(tab);
+    expect(vm.tabClicked).toHaveBeenCalledWith(tab);
+  });
+
+  it('renders a spinner if tab is loading', () => {
+    const tab = {
+      loading: true,
+      url: 'url',
+    };
+    const vm = createComponent({
+      tab,
+    });
+    const close = vm.$el.querySelector('.close');
+    const name = vm.$el.querySelector(`a[title="${tab.url}"]`);
+
+    expect(close).toBeFalsy();
+    expect(name).toBeFalsy();
+    expect(vm.$el.querySelector('.fa.fa-spinner.fa-spin')).toBeTruthy();
+  });
+
+  it('renders an fa-circle icon if tab is changed', () => {
+    const tab = {
+      loading: false,
+      url: 'url',
+      name: 'name',
+      changed: true,
+    };
+    const vm = createComponent({
+      tab,
+    });
+    const close = vm.$el.querySelector('.close');
+
+    expect(close.querySelector('.fa-circle')).toBeTruthy();
+  });
+});