function add (a, b) {
  return a + b
}

function add (a, b) {
  return a + b
}
if (!module.parent) {
  console.log(add(2, 3))
}
// node ./add
// 5

function add (a, b) {
  return a + b
}
module.exports = add
if (!module.parent) {
  console.log(add(2, 3))
}
// node ./add
// 5

test('2 + 3', () => {
  const add = require('./add')
  expect(add(1, 2)).toBe(3)
})

$ npm t

> add@1.0.0 test /add
> jest

 PASS  ./test.js
  ✓ 2 + 3 (35ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        0.96s
Ran all test suites.

$ npm t -- --coverage

> add@1.0.0 test /Users/gleb/git/training/javascript/add
> jest "--coverage"

 PASS  ./test.js
  ✓ 2 + 3 (341ms)

----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |       75 |       50 |      100 |       75 |                   |
 add.js   |       75 |       50 |      100 |       75 |                 6 |
----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.167s
Ran all test suites.

open coverage/lcov-report/index.html

require = require('really-need')
test('2 + 3', () => {
  const add = require('./add', {
    parent: undefined
  })
  expect(add(1, 2)).toBe(3)
})

require = require('really-need')
test('2 + 3', () => {
  const add = require('./add', {
    parent: undefined
  })
  expect(add(1, 2)).toBe(3)
})

require = require('really-need')
test('2 + 3', () => {
  const add = require('./add', {
    parent: undefined
  })
  expect(add(1, 2)).toBe(3)
})

const exec = require('execa-wrap')
test('2 + 3', () => {
  return exec('node', ['./add'])
  .then(result => {
    expect(result).toContain('5')
  })
})

command: node ./add
code: 0
failed: false
killed: false
signal: null
timedOut: false

stdout:
-------
5
-------
stderr:
-------

-------

expect(add(1, 2)).toBe(3)

exec('node', ['./add'])
.then(result => {
  expect(result).toContain('5')
})

$ npm t -- --coverage

> add@1.0.0 test /Users/gleb/git/training/javascript/add
> jest "--coverage"

 PASS  ./test.js
  ✓ 2 + 3 (77ms)

5
----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |        0 |        0 |        0 |        0 |                   |
----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        1.323s
Ran all test suites.

// change test to
return exec('nyc', 
  ['--reporter=lcov', 'node', './add'])
// npm i -D nyc

const isEmail = (s) =>
  /^\w+@\w+\.\w{3,4}$/.test(s)

// 1 test = 100% code coverage

mocha -r data-cover spec.js

$ npm install -D cypress

it('opens the page', () => {
  cy.visit('http://localhost:3000')
  cy.get('.new-todo')
    .should('be.visible')
})

it('adds 2 todos', () => {
  cy.visit('http://localhost:3000')
  cy.get('.new-todo')
    .type('learn testing{enter}')
    .type('be cool{enter}')
  cy.get('.todo-list li')
    .should('have.length', 2)
})

if (process.env.NODE_ENV === 'production') {
    var raven = require('raven');
    var SENTRY_DSN = 'https://<DSN>@app.getsentry.com/...';
    var client = new raven.Client(SENTRY_DSN);
    client.patchGlobal();
}
foo.bar // this Error will be reported

npm install raven --save

const la = require('lazy-ass')
const is = require('check-more-types')
la(is.strings(names), 'expected list of names', names)
la(is.email(loginName), 'missing email')
la(is.version(tag) || check.sha(tag), 'invalid tag', tag)

function getAddress() {
  // "address" is nested inside the result object
  return db.fetch(...)
    .then(R.path(['customer', 'address']))
    .then(Maybe.fromNullable)
    .then(R.map(objectToCamelCase))
}

{
  "title": "Todo",
  "type": "object",
  "properties": {
     text: {
       type: 'string',
       description: 'Todo text, like "clean room"',
     },
     done: {
       type: 'boolean',
       description: 'Is this todo item completed?',
     }
  },
  "required": ["text", "done"]
}

const Todo100: ObjectSchema = {
  version: '1.0.0',
  schema: {
    title: 'Todo', type: 'object',
    description: 'Todo item sent by the client',
    properties: {
      text: {
        type: 'string',
        description: 'Todo text, like "clean room"',
      },
      done: {
        type: 'boolean',
        description: 'Is this todo item completed?',
      },
    },
    required: true, additionalProperties: false,
  },
  example: {
    text: 'do something',
    done: false
  }
}

const {assertSchema} = require('@cypress/schema-tools')
const assertTodoRequest = 
  assertSchema(schemas)('Todo', '1.0.0')
assertTodoRequest({
  done: true
})

Schema Todo@1.0.0 violated

Errors:
data.text is required

Current object:
{
  done: true
}

Expected object like this:
{
  done: false,
  text: "do something"
}

api.assertSchema('Todo', '1.0.0')(response.body)
expect(
  api.sanitize('Todo', '1.0.0)(response.body)
).toMatchSnapshot()