Set up jest with babel. Add failing test to see if it passes CI

.github/workflows/build-and-test.yml

@@ -39,7 +39,7 @@ jobs:
         run: bundle install
       - name: Create DB
         run: bundle exec rake db:test:prepare
-      - name: Run tests
+      - name: Run rails tests
         run: bundle exec rake
       - name: Install javascript dependencies
         run: yarn install

app/assets/javascripts/jester.js

@@ -0,0 +1,7 @@
+export default class Jester {
+  constructor(){}
+
+  hello(){
+    return "Hello"
+  }
+}

babel.config.js

@@ -0,0 +1,5 @@
+'use strict';
+
+module.exports = {
+  presets: ['@babel/preset-env'],
+};

package.json

@@ -2,9 +2,24 @@
   "name": "app",
   "private": "true",
   "dependencies": {
+    "@babel/preset-env": "^7.15.8",
+    "babel-preset-es2015": "^6.24.1",
     "esbuild": "^0.13.6"
   },
   "scripts": {
-    "build": "esbuild app/javascript/*.* --bundle --outdir=app/assets/builds"
+    "build": "esbuild app/javascript/*.* --bundle --outdir=app/assets/builds",
+    "test": "jest"
+  },
+  "devDependencies": {
+    "jest": "^27.2.5"
+  },
+  "jest": {
+   "roots": [
+       "./spec/javascript"
+    ],
+   "moduleDirectories": [
+     "node_modules",
+     "app/assets/javascripts"
+    ]
   }
 }

scripts/ship-it.sh

@@ -4,4 +4,4 @@ set -eux
 
 git rev-parse --show-toplevel
 
-bundle exec rake && git push
+bundle exec rake && yarn test && git push

spec/javascript/hello_jest.spec.js

@@ -0,0 +1,15 @@
+import Jester from "jester"
+
+describe('this test should pass', () => {
+  test('very first test', () => {
+    expect(true).toBe(true)
+  })
+
+  test('Jester.hello returns greeting', () =>{
+    const jester = new Jester()
+    expect(jester.hello()).toBe("Hello")
+  })
+  test('fail', () => {
+    expect(false).toBe(true)
+  })
+})