Add ability to use image snapshots to addon-storyshots

.circleci/config.yml

@@ -58,6 +58,14 @@ jobs:
           name: "Link packages"
           command: |
             yarn install
+      - run:
+          name: Workaround for https://github.com/GoogleChrome/puppeteer/issues/290
+          command: sh ./scripts/workaround-puppeteer-issue-290.sh
+      - run:
+          name: "Build official-storybook"
+          command: |
+            cd examples/official-storybook
+            yarn build-storybook
       - run:
           name: "Build react kitchen-sink"
           command: |
@@ -73,34 +81,33 @@ jobs:
           command: |
             cd examples/angular-cli
             yarn build-storybook
-
       - run:
-          name: "Run react kitchen-sink"
+          name: "Run react kitchen-sink (smoke test)"
           command: |
             cd examples/cra-kitchen-sink
-            yarn storybook
-          background: true
+            yarn storybook --smoke-test
       - run:
-          name: "Run vue kitchen-sink"
+          name: "Run vue kitchen-sink (smoke test)"
           command: |
             cd examples/vue-kitchen-sink
-            yarn storybook
-          background: true
+            yarn storybook --smoke-test
       - run:
-          name: "Run angular-cli"
+          name: "Run angular-cli (smoke test)"
           command: |
             cd examples/angular-cli
-            yarn storybook
-          background: true
+            yarn storybook --smoke-test
       - run:
-          name: Workaround for https://github.com/GoogleChrome/puppeteer/issues/290
-          command: sh ./scripts/workaround-puppeteer-issue-290.sh
+          name: "Run image snapshots"
+          command: yarn test --image
       - run:
           name: Integration Test - Kichen sinks
           command: yarn test --integration
       - store_artifacts:
           path: integration/__image_snapshots__
           destination: integration_image_snapshots
+      - store_artifacts:
+          path: examples/official-storybook/image-snapshots/__image_snapshots__
+          destination: official_storybook_image_snapshots
   react-native:
     <<: *defaults
     steps:

.gitignore

@@ -21,3 +21,4 @@ package-lock.json
 storybook-static
 integration/__image_snapshots__/__diff_output__
 .jest-test-results.json
+/examples/cra-kitchen-sink/src/__image_snapshots__/__diff_output__/

CONTRIBUTING.md

@@ -76,6 +76,14 @@ In order for the snapshot-integration tests to be executed properly, examples be
 
 Puppeteer is used to launch and grab screenshots of example pages, while jest is used to assert matching images.
 
+##### CRA-kitchen-sink - Image snapshots using Storyshots
+
+`yarn test --image`
+
+This option executes tests from `<rootdir>/examples/cra-kitchen-sink`
+In order for the image snapshots to be correctly generated, you must have static build of the storybook up-to-date.
+
+Puppeteer is used to launch and grab screenshots of example pages, while jest is used to assert matching images. (just like integration tests)
 
 #### 2b. Run e2e tests for CLI
 

addons/storyshots/README.md

@@ -36,7 +36,7 @@ Usually, you might already have completed this step. If not, here are some resou
 
 > Note: If you use React 16, you'll need to follow [these additional instructions](https://github.com/facebook/react/issues/9102#issuecomment-283873039).
 
-## Configure Storyshots
+## Configure Storyshots for HTML snapshots
 
 Create a new test file with the name `Storyshots.test.js`. (Or whatever the name you prefer, as long as it matches Jest's config [`testMatch`](http://facebook.github.io/jest/docs/en/configuration.html#testmatch-array-string)).
 Then add following content to it:
@@ -53,6 +53,103 @@ Now run your Jest test command. (Usually, `npm test`.) Then you can see all of y
 
 ![Screenshot](docs/storyshots.png)
 
+
+## Configure Storyshots for image snapshots
+
+/*\ **React-native** is **not supported** by this test function.
+
+Internally, it uses [jest-image-snapshot](https://github.com/americanexpress/jest-image-snapshot).
+
+When willing to generate and compare image snapshots for your stories, you have to two options: 
+ - Have a storybook running (ie. accessible via http(s):// , for instance using `yarn run storybook`)
+ - Have a static build of the storybook (for instance, using `yarn run build-storybook`)
+
+Then you will need to reference the storybook URL (`file://...` if local, `http(s)://...` if served)
+
+### Using default values for _imageSnapshots_
+
+Then you can either create a new Storyshots instance or edit the one you previously used: 
+```js
+import initStoryshots, { imageSnapshot } from '@storybook/addon-storyshots';
+
+initStoryshots({suite: 'Image storyshots', test: imageSnapshot});
+```
+This will assume you have a storybook running on at _http://localhost:6006_.
+Internally here are the steps:  
+- Launches a Chrome headless using [puppeteer](https://github.com/GoogleChrome/puppeteer)
+- Browses each stories (calling _http://localhost:6006/iframe.html?..._ URL),
+- Take screenshots & save all images under _\_image_snapshots\__ folder.
+
+### Specifying the storybook URL
+
+If you want to set specific storybook URL, you can specify via the `storybookUrl` parameter, see below: 
+```js
+import initStoryshots, { imageSnapshot } from '@storybook/addon-storyshots';
+
+initStoryshots({suite: 'Image storyshots', test: imageSnapshot({storybookUrl: 'http://my-specific-domain.com:9010'})});
+```
+The above config will use _https://my-specific-domain.com:9010_ for screenshots.
+
+
+You may also use a local static build of storybook if you do not want to run the webpack dev-server:
+```js
+import initStoryshots, { imageSnapshot } from '@storybook/addon-storyshots';
+
+initStoryshots({suite: 'Image storyshots', test: imageSnapshot({storybookUrl: 'file:///path/to/my/storybook-static'})});
+```
+
+### Specifying options to _jest-image-snapshots_
+
+If you wish to customize [jest-image-snapshot](https://github.com/americanexpress/jest-image-snapshot), then you can provide a `getMatchOptions` parameter that should return the options config object.
+```js
+import initStoryshots, { imageSnapshot } from '@storybook/addon-storyshots';
+const getMatchOptions = ({context : {kind, story}, url}) => {
+  return {
+    failureThreshold: 0.2,
+    failureThresholdType: 'percent',
+  }
+}
+initStoryshots({suite: 'Image storyshots', test: imageSnapshot({storybookUrl: 'http://localhost:6006', getMatchOptions})});
+```
+`getMatchOptions` receives an object: `{ context: {kind, story}, url}`. _kind_ is the kind of the story and the _story_ its name. _url_ is the URL the browser will use to screenshot.
+
+
+### Integrate image storyshots with regular app
+You may want to use another Jest project to run your image snapshots as they require more resources: Chrome and Storybook built/served.
+You can find a working example of this in the [official-storybook](https://github.com/storybooks/storybook/tree/master/examples/official-storybook) example.
+
+### Integrate image storyshots with [Create React App](https://github.com/facebookincubator/create-react-app)
+You have two options here, you can either: 
+
+- Simply add the storyshots configuration inside any of your `test.js` file. You must ensure you have either a running storybook or a static build available.
+
+- Create a custom test file using Jest outside of the CRA scope:
+
+    A more robust approach would be to separate existing test files ran by create-react-app (anything `(test|spec).js` suffixed files) from the test files to run storyshots with image snapshots.
+    This use case can be achieved by using a custom name for the test file, ie something like `image-storyshots.runner.js`. This file will contains the `initStoryshots` call with image snapshots configuration.
+    Then you will create a separate script entry in your package.json, for instance 
+    ```json
+    {
+        "scripts": { 
+            "image-snapshots" : "jest image-storyshots.runner.js --config path/to/custom/jest.config.json"
+        }
+    }
+    ```
+    Note that you will certainly need a custom config file for Jest as you run it outside of the CRA scope and thus you do not have the built-in config.
+
+    Once that's setup, you can run `yarn run image-snapshots` (or `npm run image-snapshots`).
+
+### Reminder
+An image snapshot is simply a screenshot taken by a web browser (in our case, Chrome).
+
+The browser opens a page (either using the static build of storybook or a running instance of Storybook)
+
+If you run your test without either the static build or a running instance, this wont work.
+
+To make sure your screenshots are taken from latest changes of your Storybook, you must keep your static build or running Storybook up-to-date. 
+This can be achieved by adding a step before running the test ie: `yarn run build-storybook && yarn run image-snapshots`.
+If you run the image snapshots against a running Storybook in dev mode, you don't have to care about being up-to-date because the dev-server is watching changes and rebuilds automatically.
+
 ## Options
 
 ### `configPath`

addons/storyshots/package.json

@@ -21,7 +21,9 @@
     "glob": "^7.1.2",
     "global": "^4.3.2",
     "jest-specific-snapshot": "^0.3.0",
+    "jest-image-snapshot": "^2.2.0",
     "prop-types": "^15.6.0",
+    "puppeteer": "^0.13.0",
     "read-pkg-up": "^3.0.0"
   },
   "devDependencies": {

addons/storyshots/src/index.js

@@ -1,7 +1,7 @@
 import path from 'path';
 import fs from 'fs';
 import glob from 'glob';
-import global, { describe, it } from 'global';
+import global, { describe, it, beforeEach, afterEach } from 'global';
 import readPkgUp from 'read-pkg-up';
 import addons from '@storybook/addons';
 
@@ -18,6 +18,8 @@ export {
   renderOnly,
 } from './test-bodies';
 
+export { imageSnapshot } from './test-body-image-snapshot';
+
 export { getSnapshotFileName };
 
 let storybook;
@@ -100,6 +102,20 @@ export default function testStorySnapshots(options = {}) {
     }
 
     describe(suite, () => {
+      beforeEach(() => {
+        if (typeof options.test.beforeEach === 'function') {
+          return options.test.beforeEach();
+        }
+        return Promise.resolve();
+      });
+
+      afterEach(() => {
+        if (typeof options.test.afterEach === 'function') {
+          return options.test.afterEach();
+        }
+        return Promise.resolve();
+      });
+
       describe(kind, () => {
         // eslint-disable-next-line
         for (const story of group.stories) {
@@ -109,7 +125,7 @@ export default function testStorySnapshots(options = {}) {
           }
 
           it(story.name, () => {
-            const context = { fileName, kind, story: story.name };
+            const context = { fileName, kind, story: story.name, isRNStorybook };
             return options.test({
               story,
               context,
@@ -122,14 +138,13 @@ export default function testStorySnapshots(options = {}) {
 }
 
 describe('Storyshots Integrity', () => {
-  describe('Abandoned Storyshots', () => {
+  test('Abandoned Storyshots', () => {
     const storyshots = glob.sync('**/*.storyshot');
 
     const abandonedStoryshots = storyshots.filter(fileName => {
       const possibleStoriesFiles = getPossibleStoriesFiles(fileName);
       return !possibleStoriesFiles.some(fs.existsSync);
     });
-
     expect(abandonedStoryshots).toHaveLength(0);
   });
 });

addons/storyshots/src/test-body-image-snapshot.js

@@ -0,0 +1,67 @@
+import puppeteer from 'puppeteer';
+import { toMatchImageSnapshot } from 'jest-image-snapshot';
+
+expect.extend({ toMatchImageSnapshot });
+
+export const imageSnapshot = ({
+  storybookUrl = 'http://localhost:6006',
+  getMatchOptions = () => {},
+}) => {
+  let browser; // holds ref to browser. (ie. Chrome)
+  let page; // Hold ref to the page to screenshot.
+
+  const testFn = ({ context }) => {
+    if (context.isRNStorybook) {
+      // Skip tests since we de not support RN image snapshots.
+      console.error(
+        "It seems you are running imageSnapshot on RN app and it's not supported. Skipping test."
+      );
+      return Promise.resolve();
+    }
+
+    const encodedKind = encodeURIComponent(context.kind);
+    const encodedStoryName = encodeURIComponent(context.story);
+    const storyUrl = `/iframe.html?selectedKind=${encodedKind}&selectedStory=${encodedStoryName}`;
+    const url = storybookUrl + storyUrl;
+    if (!browser || !page) {
+      console.error(
+        `Error when generating image snapshot for test ${context.kind} - ${
+          context.story
+        } : It seems the headless browser is not running.`
+      );
+      return Promise.reject(new Error('no-headless-browser-running'));
+    }
+
+    expect.assertions(1);
+    return page
+      .goto(url)
+      .catch(e => {
+        console.error(
+          `ERROR WHILE CONNECTING TO ${url}, did you start or build the storybook first ? A storybook instance should be running or a static version should be built when using image snapshot feature.`,
+          e
+        );
+        throw e;
+      })
+      .then(() =>
+        page.screenshot().then(image => {
+          expect(image).toMatchImageSnapshot(getMatchOptions({ context, url }));
+        })
+      );
+  };
+
+  testFn.beforeEach = () =>
+    puppeteer
+      // add some options "no-sandbox" to make it work properly on some Linux systems as proposed here: https://github.com/Googlechrome/puppeteer/issues/290#issuecomment-322851507
+      .launch({ args: ['--no-sandbox ', '--disable-setuid-sandbox'] })
+      .then(b => {
+        browser = b;
+      })
+      .then(() => browser.newPage())
+      .then(p => {
+        page = p;
+      });
+
+  testFn.afterEach = () => browser.close();
+
+  return testFn;
+};

examples/cra-kitchen-sink/package.json

@@ -5,7 +5,6 @@
     "build": "react-scripts build",
     "build-storybook": "build-storybook -s public",
     "eject": "react-scripts eject",
-    "generate-addon-jest-testresults": "jest src/stories/addon-jest.test.js --config=config-addon-jest.json --env=jsdom --json --outputFile=src/stories/addon-jest.testresults.json",
     "start": "react-scripts start",
     "storybook": "start-storybook -p 9010 -s public",
     "test": "react-scripts test --env=jsdom"