Add cypress and test adding an item

- Also add eslint plugin for cypress and @testin-library/cypress bindings
This test is skipped since it mutates the shared app state—running it adds the same item over and over.
We'll need to add delete functionality, create a test user, and/or stub the firebase network request to have a solid test.
Otherwise, we'll constantly need to login to the firebase console to delete the test data.

cypress.json

@@ -0,0 +1,4 @@
+{
+  "baseUrl": "http://localhost:3000",
+  "$schema": "https://on.cypress.io/cypress.schema.json"
+}

cypress/fixtures/example.json

@@ -0,0 +1,5 @@
+{
+  "name": "Using fixtures to represent data",
+  "email": "hello@cypress.io",
+  "body": "Fixtures are a great way to mock data for responses to routes"
+}

cypress/integration/home.spec.js

@@ -0,0 +1,15 @@
+describe('Home page', function() {
+  // TODO: Get app into empty test state with test user or API call to delete avocados. Or stub the request.
+  it.skip('adds an item to the list', function() {
+    const itemName = 'avocados';
+
+    cy.visit('/');
+
+    cy.findByLabelText('Add Item:')
+      .type(itemName)
+      .findByText('Add Item')
+      .click()
+      .findByLabelText('shopping list')
+      .contains(itemName);
+  });
+});

cypress/plugins/index.js

@@ -0,0 +1,17 @@
+// ***********************************************************
+// This example plugins/index.js can be used to load plugins
+//
+// You can change the location of this file or turn off loading
+// the plugins file with the 'pluginsFile' configuration option.
+//
+// You can read more here:
+// https://on.cypress.io/plugins-guide
+// ***********************************************************
+
+// This function is called when a project is opened or re-opened (e.g. due to
+// the project's config changing)
+
+module.exports = (on, config) => {
+  // `on` is used to hook into various events Cypress emits
+  // `config` is the resolved Cypress config
+}

cypress/support/commands.js

@@ -0,0 +1,27 @@
+import '@testing-library/cypress/add-commands';
+
+// ***********************************************
+// This example commands.js shows you how to
+// create various custom commands and overwrite
+// existing commands.
+//
+// For more comprehensive examples of custom
+// commands please read more here:
+// https://on.cypress.io/custom-commands
+// ***********************************************
+//
+//
+// -- This is a parent command --
+// Cypress.Commands.add("login", (email, password) => { ... })
+//
+//
+// -- This is a child command --
+// Cypress.Commands.add("drag", { prevSubject: 'element'}, (subject, options) => { ... })
+//
+//
+// -- This is a dual command --
+// Cypress.Commands.add("dismiss", { prevSubject: 'optional'}, (subject, options) => { ... })
+//
+//
+// -- This will overwrite an existing command --
+// Cypress.Commands.overwrite("visit", (originalFn, url, options) => { ... })

cypress/support/index.js

@@ -0,0 +1,20 @@
+// ***********************************************************
+// This example support/index.js is processed and
+// loaded automatically before your test files.
+//
+// This is a great place to put global configuration and
+// behavior that modifies Cypress.
+//
+// You can change the location of this file or turn off
+// automatically serving support files with the
+// 'supportFile' configuration option.
+//
+// You can read more here:
+// https://on.cypress.io/configuration
+// ***********************************************************
+
+// Import commands.js using ES2015 syntax:
+import './commands'
+
+// Alternatively you can use CommonJS syntax:
+// require('./commands')

package.json

@@ -17,10 +17,14 @@
     "build": "react-scripts build",
     "test": "react-scripts test",
     "eject": "react-scripts eject",
-    "format": "prettier --write 'src/**/*.{js,jsx,ts,tsx,json,css,scss,md}'"
+    "format": "prettier --write 'src/**/*.{js,jsx,ts,tsx,json,css,scss,md}'",
+    "cy:open": "cypress open"
   },
   "eslintConfig": {
-    "extends": "react-app"
+    "extends": [
+      "react-app",
+      "plugin:cypress/recommended"
+    ]
   },
   "husky": {
     "hooks": {
@@ -44,5 +48,10 @@
       "last 1 firefox version",
       "last 1 safari version"
     ]
+  },
+  "devDependencies": {
+    "@testing-library/cypress": "^5.0.2",
+    "cypress": "^3.8.0",
+    "eslint-plugin-cypress": "^2.8.1"
   }
 }

src/pages/List.js

@@ -17,7 +17,7 @@ const List = () => {
             <Loading />
           ) : (
             <main>
-              <ul>
+              <ul aria-label="shopping list">
                 {data.map(item => (
                   <li key={item.id}>{item.name}</li>
                 ))}