Adds a url sync component

This adds a component that allows you to sync a query with the current
page URL.

app/assets/javascripts/vue_shared/components/url_sync.vue

+<script>
+import { historyPushState } from '~/lib/utils/common_utils';
+import { setUrlParams } from '~/lib/utils/url_utility';
+
+export default {
+  props: {
+    query: {
+      type: Object,
+      required: true,
+    },
+  },
+  watch: {
+    query: {
+      immediate: true,
+      deep: true,
+      handler(newQuery) {
+        historyPushState(setUrlParams(newQuery, window.location.href, true));
+      },
+    },
+  },
+  render() {
+    return this.$slots.default;
+  },
+};
+</script>

ee/spec/frontend/vue_shared/components/url_sync_spec.js

+import { shallowMount } from '@vue/test-utils';
+import { historyPushState } from '~/lib/utils/common_utils';
+import { setUrlParams } from '~/lib/utils/url_utility';
+import UrlSyncComponent from '~/vue_shared/components/url_sync.vue';
+import setWindowLocation from 'helpers/set_window_location_helper';
+
+jest.mock('~/lib/utils/url_utility', () => ({
+  setUrlParams: jest.fn(val => `urlParams: ${val}`),
+}));
+
+jest.mock('~/lib/utils/common_utils', () => ({
+  historyPushState: jest.fn(),
+}));
+
+describe('url sync component', () => {
+  let wrapper;
+  const mockQuery = { group_id: '5014437163714', project_ids: ['5014437608314'] };
+  const TEST_HOST = 'http://testhost/';
+
+  jest.mock();
+  setWindowLocation(TEST_HOST);
+
+  const createComponent = () => {
+    wrapper = shallowMount(UrlSyncComponent, {
+      propsData: { query: mockQuery },
+    });
+  };
+
+  function expectUrlSync(query) {
+    expect(setUrlParams).toHaveBeenCalledTimes(1);
+    expect(setUrlParams).toHaveBeenCalledWith(query, TEST_HOST, true);
+
+    const setUrlParamsReturnValue = setUrlParams.mock.results[0].value;
+    expect(historyPushState).toHaveBeenCalledTimes(1);
+    expect(historyPushState).toHaveBeenCalledWith(setUrlParamsReturnValue);
+  }
+
+  beforeEach(() => {
+    createComponent();
+  });
+
+  it('immediately syncs the query to the URL', () => expectUrlSync(mockQuery));
+
+  describe('when the query is modified', () => {
+    const newQuery = { foo: true };
+    beforeEach(() => {
+      setUrlParams.mockClear();
+      historyPushState.mockClear();
+      wrapper.setProps({ query: newQuery });
+    });
+
+    it('updates the URL with the new query', () => expectUrlSync(newQuery));
+  });
+});