From 1c85c5293ebbcd4be2cddeeddf890981df369dd3 Mon Sep 17 00:00:00 2001
From: Wil Wilsman <wil@wilwilsman.com>
Date: Thu, 17 Mar 2022 15:09:23 -0500
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20Add=20sdk-utils=20waitForPercyIdle?=
 =?UTF-8?q?=20helper=20(#831)?=
MIME-Version: 1.0
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---
 packages/sdk-utils/src/index.js       |  2 ++
 packages/sdk-utils/src/percy-idle.js  | 13 +++++++++++++
 packages/sdk-utils/test/index.test.js | 21 +++++++++++++++++++++
 packages/sdk-utils/test/server.js     |  3 ++-
 4 files changed, 38 insertions(+), 1 deletion(-)
 create mode 100644 packages/sdk-utils/src/percy-idle.js

diff --git a/packages/sdk-utils/src/index.js b/packages/sdk-utils/src/index.js
index 460cc9ade..b77e496f9 100644
--- a/packages/sdk-utils/src/index.js
+++ b/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
 };
diff --git a/packages/sdk-utils/src/percy-idle.js b/packages/sdk-utils/src/percy-idle.js
new file mode 100644
index 000000000..e4fb88cff
--- /dev/null
+++ b/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;
diff --git a/packages/sdk-utils/test/index.test.js b/packages/sdk-utils/test/index.test.js
index 60f4593e2..9bfcfc05d 100644
--- a/packages/sdk-utils/test/index.test.js
+++ b/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;
 
diff --git a/packages/sdk-utils/test/server.js b/packages/sdk-utils/test/server.js
index 6729904f5..eadfc7110 100644
--- a/packages/sdk-utils/test/server.js
+++ b/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) => {