✨ Add sdk-utils waitForPercyIdle helper

packages/sdk-utils/src/index.js

@@ -2,6 +2,7 @@ import logger from '@percy/logger';
 import percy from './percy-info';
 import request from './request';
 import isPercyEnabled from './percy-enabled';
+import waitForPercyIdle from './percy-idle';
 import fetchPercyDOM from './percy-dom';
 import postSnapshot from './post-snapshot';
 
@@ -13,6 +14,7 @@ export {
   percy,
   request,
   isPercyEnabled,
+  waitForPercyIdle,
   fetchPercyDOM,
   postSnapshot
 };

packages/sdk-utils/src/percy-idle.js

@@ -0,0 +1,13 @@
+import request from './request';
+
+const RETRY_ERROR_CODES = ['ECONNRESET', 'ETIMEDOUT'];
+
+export async function waitForPercyIdle() {
+  try {
+    return !!(await request('/percy/idle'));
+  } catch (e) {
+    return RETRY_ERROR_CODES.includes(e.code) && waitForPercyIdle();
+  }
+}
+
+export default waitForPercyIdle;

packages/sdk-utils/test/index.test.js

@@ -126,6 +126,27 @@ describe('SDK Utils', () => {
     });
   });
 
+  describe('waitForPercyIdle()', () => {
+    let { waitForPercyIdle } = utils;
+
+    it('gets idle state from the CLI API idle endpoint', async () => {
+      await expectAsync(waitForPercyIdle()).toBeResolvedTo(true);
+      await expectAsync(helpers.getRequests()).toBeResolvedTo([['/percy/idle']]);
+    });
+
+    it('polls the CLI API idle endpoint on timeout', async () => {
+      spyOn(utils.request, 'fetch').and.callFake((...args) => {
+        return utils.request.fetch.calls.count() > 2
+          ? utils.request.fetch.and.originalFn(...args)
+          // eslint-disable-next-line prefer-promise-reject-errors
+          : Promise.reject({ code: 'ETIMEDOUT' });
+      });
+
+      await expectAsync(waitForPercyIdle()).toBeResolvedTo(true);
+      expect(utils.request.fetch).toHaveBeenCalledTimes(3);
+    });
+  });
+
   describe('fetchPercyDOM()', () => {
     let { fetchPercyDOM } = utils;
 

packages/sdk-utils/test/server.js

@@ -50,7 +50,8 @@ function context() {
         { success: true, config: { snapshot: { widths: [1280] } } })],
       '/percy/config': ({ body }) => [200, 'application/json', (
         { success: true, config: body })],
-      '/percy/snapshot': () => [200, 'application/json', { success: true }]
+      '/percy/snapshot': () => [200, 'application/json', { success: true }],
+      '/percy/idle': () => [200, 'application/json', { success: true }]
     }, 5338);
 
     ctx.server.route((req, res, next) => {