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effects-as-data

Effects as Data

effects-as-data is a library that allows you to express your business logic using only pure functions, anywhere that Javascript runs. effects-as-data makes it easy to reason about your code and makes it hard to write hard-to-test code, getting rid of the need for mocks, stubs, spies, globals, and interaction testing.

Why use effects as data?

  • It makes development faster.
  • Its hard to write hard-to-test code. If you like testing, you'll love effects-as-data.
  • Service discovery is no longer a thing. No need for dependency injection, exposing services as singletons, etc. Services and state are available everywhere all the time, without being global.
  • All business logic is expressed using only pure functions.
  • One testing methodology for everything. Say goodbye to mocks, stubs, spies, globals, and interaction testing. Just pure-function, deepEqual(input, output) style testing.
  • Logicless tests. Tests have no assertions.
  • Decouple protocol from implementation.
  • Independently monitor all side effects in the system.

Example

A side-by-side example of the same code written in traditional-style javascript and in effects-as-data: https://github.com/orourkedd/effects-as-data-vs-side-effects. This came from a talk given at the Pluralsight Tech Summit.

Installation

npm i --save effects-as-data

Try It

You can run the code below using this command. You can see the code here.

npm install
npm run demo

Effects-as-data lifecycle

Effects-as-data lifecycle

Usage

Write a pure function expressing your business logic

Define a pure function that effects-as-data can use to perform your business logic. This function coordinates your workflow. The function below does a lot and would normally be difficult to test:

  • Reads user input (a Github username).
  • Does a GET request to Github for the user's repositories.
  • Prints an array of the user's repository names.
  • Returns the array of repository names.

NOTE: prompt, httpGet, logInfo below are pure functions which only return JSON objects. They are not actually prompting, httpGeting, etc. effects-as-data routes these JSON objects to handlers that do the side-effect-producing, hard-to-test part for you. The code below performs no side-effects, nor does it have any reference to side-effect-producing code.

You can find this in demo-cli/functions/save-repositories.js

const { actions, isFailure } = require('effects-as-data/node')
const { pluck } = require('ramda')
const getListOfNames = pluck(['name'])
 
const saveRepositories = function * (filename) {
  const {payload: username} = yield actions.prompt('\nEnter a github username: ')
  const repos = yield actions.httpGet(`https://api.github.com/users/${username}/repos`)
  if (isFailure(repos)) return repos
  const names = getListOfNames(repos.payload)
  yield actions.logInfo(names.join('\n'))
  return names
}
 
module.exports = {
  saveRepositories
}

Test It

Test your business logic using logic-less tests. Each tuple in the array is an input-output pair. You can find this in demo-cli/functions/save-repositories.spec.js:

const { testIt } = require('effects-as-data/test')
const { saveRepositories } = require('./save-repositories')
const { actions, failure } = require('effects-as-data/node')
 
const testSaveRepositories = testIt(saveRepositories)
 
describe('saveRepositories()', () => {
  it('should get repositories and print names', testSaveRepositories(() => {
    const repos = [
      { name: 'foo' },
      { name: 'bar' }
    ]
    return [
      ['repos.json', actions.prompt('\nEnter a github username: ')],
      ['orourkedd', actions.httpGet('https://api.github.com/users/orourkedd/repos')],
      [repos, actions.logInfo('foo\nbar')],
      [null, ['foo', 'bar']]
    ]
  }))
 
  it('should return http GET failure', testSaveRepositories(() => {
    const httpError = new Error('http error!')
    return [
      ['repos.json', actions.prompt('\nEnter a github username: ')],
      ['orourkedd', actions.httpGet('https://api.github.com/users/orourkedd/repos')],
      [failure(httpError), failure(httpError)]
    ]
  }))
})
 
 

Debug

If your tests are failing, you get a message like this:

Error on Step 4
 
Actual:
{ type: 'writeFile',
  path: 'wrong-path.json',
  data: '...
}
 
Expected:
{ type: 'writeFile',
  path: 'repos.json',
  data: '...'
}

Wire It Up and Run It

Fifth, wire it all up. You can find this in demo-cli/index.js:

const { run, handlers } = require('effects-as-data/node')
const { saveRepositories } = require('./functions/save-repositories')
 
run(handlers, saveRepositories, 'repos.json').catch(console.error)
 

Logging Action Failures

Logging all action failures explicitly can add a lot of noise to your code. Effects-as-data provides an onFailure hook that will be called for each failed action with a detailed payload about the error. This allows for every effect in the system to be independently monitored and reported on, automatically.

function onFailure (payload) {
  //  payload: 
  //  { 
  //   fn: 'saveRepositories', 
  //   log: [ 
  //     [42, {type: 'firstAction'}], 
  //     [{success: true, payload: 'something from firstAction'}, {type: 'theFailingAction'}] 
  //   ], 
  //   failure: { 
  //     success: false, 
  //     error: { 
  //       message: 'Some happened on this line for that reason' 
  //     } 
  //   }, 
  //   action: {type: 'theFailingAction'} 
  // } 
 
  myLoggingFn(payload)
}
 
function * test () {
  yield { type: 'firstAction' }
  yield { type: 'theFailingAction' }
}
 
return run(handlers, test, 42, {
  name: 'testFunction',
  onFailure
})

Actions packaged with effects-as-data

Table of Contents

env

src/actions/node/env.js:33-37

Create an env action. yield an env action get process.env.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/node')
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return the environment', testExample(() => {
    return [
      [null, actions.env()],
      [{ NODE_ENV: 'development' }, success({ NODE_ENV: 'development' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/node')
 
function * example () {
  const result = yield actions.env()
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/node')
 
run(handlers, example).then((env) => {
  env.payload.NODE_ENV === 'development' //  true, if process.env.NODE_ENV === 'development' 
})

Returns Object an action of type env.

readFile

src/actions/node/fs.js:37-44

Creates a readFile action. yield a readFile action to read a file using fs.readFile.

Parameters

  • file string file path
  • options Object? options for fs.readFile (optional, default {})
  • path

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/node')
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should read a file', testExample(() => {
    const path = '/path/to/file.txt'
    return [
      [{ path }, actions.readFile(path, { encoding: 'utf8' })],
      ['FOO', success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/node')
 
function * example ({ path }) {
  const result = yield actions.readFile(path, { encoding: 'utf8' })
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/node')
 
run(handlers, example, { path: '/path/to/file.txt' }).then((result) => {
  result.payload === 'FOO' //  true, if '/path/to/file.txt' has the content 'FOO'. 
})

Returns Object an action of type readFile.

writeFile

src/actions/node/fs.js:84-91

Creates a writeFile action. yield a writeFile action to write a file using fs.writeFile.

Parameters

  • file string file path
  • the any contents to write
  • options Object? options for fs.writeFile (optional, default {})
  • path
  • data

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should write a file', testExample(() => {
    const path = '/path/to/file.txt'
    const contents = 'BAR'
    return [
      [{ path, contents }, writeFile(path, contents, { encoding: 'utf8' })],
      //  expect a `success` from writeFile and for the function to return the `success` 
      [success(), success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/node')
 
function * example ({ path, contents }) {
  const result = yield actions.writeFile(path, contents, { encoding: 'utf8' })
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/node')
 
run(handlers, example, { path: '/path/to/file.txt', contents: 'FOO' }).then((result) => {
  result.success === true && result.payload === null //  true, if write to '/path/to/file.txt' was successful. 
})

Returns Object an action of type writeFile.

prompt

src/actions/node/prompt.js:35-40

Creates a prompt action. yield a prompt action read input form a user from the command line.

Parameters

  • question string prompt for the user

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/node')
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should prompt the user', testExample(() => {
    return [
      [null, actions.prompt("What's your favorite color?")],
      ['green', success('green')]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/node')
 
function * example () {
  const result = yield actions.prompt("What's your favorite color?")
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/node')
 
run(handlers, example).then((result) => {
  result.payload === 'green' //  true, if the user typed "green" on the command line. 
})

Returns Object an action of type prompt.

requireModule

src/actions/node/require-module.js:35-40

Creates a requireModule action. yield a requireModule action to require a module.

Parameters

  • the string absolute path to the module.
  • path

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/node')
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should require a module', testExample(() => {
    return [
      [null, actions.requireModule('/path/to/my-module')],
      [{ foo: 'bar' }, success({ foo: 'bar' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/node')
 
function * example () {
  const result = yield actions.requireModule('/path/to/my-module')
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/node')
 
run(handlers, example).then((result) => {
  result.payload == { foo: 'bar' } //  true 
})

Returns Object an action of type requireModule.

call

src/actions/universal/call.js:43-50

Creates a call action. yield a call action to call another effects-as-data function. call is used to compose effects-as-data functions in a testible manner.

Parameters

  • fn Function an effects-as-data generator function.
  • payload any? the payload for the effects-as-data function.
  • options Object? options for call (optional, default {})

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should call an effects-as-data function', testExample(() => {
    return [
      ['123', actions.call(getUser, { id: '123' })],
      [{ id: '123', username: 'foo' }, success({ id: '123', username: 'foo' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * getUser ({ id }) {
 const user = yield actions.httpGet(`https://example.com/api/v1/users/${id}`)
 return user
}
 
function * example ({ id }) {
  const result = yield actions.call(getUser, { id })
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { id: '123' }).then((user) => {
  user.payload.id === '123' //  true 
  user.payload.username === 'foo' //  true, if a user with an id of '123' has the `username` 'foo'. 
})

Returns Object an action of type call.

echo

src/actions/universal/echo.js:35-40

Creates an echo action. yield an echo action for the handler to return payload. This is used as a placeholder when multiple actions are being yielded and some of the actions need to be yielded conditionally.

Parameters

  • payload any the value to be returns from the handler.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return its argument', testExample(() => {
    const value = { foo: 'bar' }
    return [
      [{ value }, actions.echo(value)],
      [value, success(value)]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ value }) {
  const result = yield actions.echo(value)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { value: 32 }).then((result) => {
  result.payload === 32 //  true 
})

Returns Object an action of type echo.

guid

src/actions/universal/guid.js:33-37

Creates a guid action. yield a guid action to get a shiny new guid.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return a guid', testExample(() => {
    return [
      [null, actions.guid()],
      ['83feb66e-cf36-40a3-ad23-a150f0b7ed4d', success('83feb66e-cf36-40a3-ad23-a150f0b7ed4d')]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example () {
  const result = yield actions.guid()
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example).then((result) => {
  result.payload === '15270902-2798-4c34-aaa8-9a55726b58af' //  true, if `uuid.v4()` returned '15270902-2798-4c34-aaa8-9a55726b58af' 
})

Returns Object an action of type guid.

httpGet

src/actions/universal/http.js:43-50

Creates a httpGet action. yield an httpGet action to do an http GET request.

Parameters

  • url string the url to GET.
  • headers Object? request headers. (optional, default {})
  • options Object? options for fetch. (optional, default {})

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return a result from GET', testExample(() => {
    return [
      [{ url: 'http://www.example.com' }, actions.httpGet('http://www.example.com')],
      [{ foo: 'bar' }, success({ foo: 'bar' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ url }) {
  const result = yield actions.httpGet(url)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const url = 'https://www.example.com/api/v1/something'
run(handlers, example, { url }).then((result) => {
  result.payload === { foo: 'bar' } //  true, if a GET to `url` returned `{ foo: 'bar' }` 
})

Returns Object an action of type httpGet.

httpPost

src/actions/universal/http.js:89-97

Creates a httpPost action. yield an httpPost action to do an http POST request.

Parameters

  • url string the url to POST.
  • payload Object? the payload to POST.
  • headers Object? request headers. (optional, default {})
  • options Object? options for fetch. (optional, default {})

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should POST payload to url', testExample(() => {
    const url = 'http://www.example.com/api/v1/user'
    return [
      [{ url }, actions.httpPost(url, { foo: 'bar' })],
      [success(), success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example (payload) {
  const result = yield actions.httpPost('http://www.example.com/api/v1/user', payload)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { foo: 'bar' }).then((result) => {
  result.success === true //  true, if a POST was successful 
})

Returns Object an action of type httpPost.

httpPut

src/actions/universal/http.js:136-144

Creates a httpPut action. yield an httpPut action to do an http PUT request.

Parameters

  • url string the url to PUT.
  • payload Object? the payload to PUT.
  • headers Object? request headers. (optional, default {})
  • options Object? options for fetch. (optional, default {})

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should PUT payload to url', testExample(() => {
    const url = 'http://www.example.com/api/v1/user'
    return [
      [{ url }, actions.httpPut(url, { foo: 'bar' })],
      [success(), success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example (payload) {
  const result = yield actions.httpPut('http://www.example.com/api/v1/user', payload)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { foo: 'bar' }).then((result) => {
  result.success === true //  true, if a PUT was successful 
})

Returns Object an action of type httpPut.

httpDelete

src/actions/universal/http.js:181-188

Creates a httpDelete action. yield an httpDelete action to do an http DELETE request.

Parameters

  • url string the url to DELETE.
  • headers Object? request headers. (optional, default {})
  • options Object? options for fetch. (optional, default {})

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return a result from DELETE', testExample(() => {
    return [
      [{ id: '32' }, actions.httpDelete('http://www.example.com/api/v1/user/32')],
      [success(), success())]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ id }) {
  const result = yield actions.httpDelete(`http://www.example.com/api/v1/user/${id}`)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { id: '123' }).then((result) => {
  result.success === true //  true, if a DELETE to http://www.example.com/api/v1/user/123 was successful 
})

Returns Object an action of type httpDelete.

jsonParse

src/actions/universal/json-parse.js:35-40

Creates a jsonParse action. yield a jsonParse action to parse a JSON string. Why not just use JSON.parse() inline? Although a successful parsing operation is deterministic, a failed parsing operation is not.

Parameters

  • payload string the JSON string to parse.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should parse a JSON string', testExample(() => {
    return [
      [{ json: '{"foo": "bar"}' }, actions.jsonParse('{"foo": "bar"}')],
      [{ foo: 'bar' }, success({ foo: 'bar' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ json }) {
  const result = yield actions.jsonParse(json)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { json: '{"foo": "bar"}' }).then((result) => {
  result.payload.foo === 'bar' //  true 
})

Returns Object an action of type jsonParse.

logInfo

src/actions/universal/log.js:35-40

Creates a logInfo action. yield a logInfo action to log to the console using console.info.

Parameters

  • payload string? the payload to log.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should log a message', testExample(() => {
    return [
      [{ message: 'foo' }, actions.logInfo('foo')],
      [null, success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ message }) {
  const result = yield actions.logInfo(message)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { message: 'bar' }).then((result) => {
  //  "bar" should have been `console.info`ed 
})

Returns Object an action of type logInfo.

logError

src/actions/universal/log.js:76-81

Creates a logError action. yield a logError action to log to the console using console.error.

Parameters

  • payload string? the payload to log.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should log a message', testExample(() => {
    return [
      [{ message: 'foo' }, actions.logError('foo')],
      [null, success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example ({ message }) {
  const result = yield actions.logError(message)
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example, { message: 'bar' }).then((result) => {
  //  "bar" should have been `console.error`ed 
})

Returns Object an action of type logError.

now

src/actions/universal/now.js:33-37

Create an now action. yield a now action to get the current timestamp from Date.now().

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return the current timestamp', testExample(() => {
    return [
      [null, actions.now()],
      [123456, success(123456)]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example () {
  const timestamp = yield actions.now()
  return timestamp
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example).then((timestamp) => {
  timestamp.payload === 1490030160103 //  true, if Date.now() returned 1490030160103 
})

Returns Object an action of type now.

randomNumber

src/actions/universal/random-number.js:33-37

Create an randomNumber action. yield a randomNumber to get a random number using Math.random().

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return the current timestamp', testExample(() => {
    return [
      [null, actions.randomNumber()],
      [0.123, success(0.123)]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example () {
  const n = yield actions.randomNumber()
  return n
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example).then((n) => {
  n.payload === 0.345 //  true, if Math.random() returned 0.345 
})

Returns Object an action of type randomNumber.

getState

src/actions/universal/state.js:34-39

Creates a getState action. yield a getState to get application state.

Parameters

  • keys Array an array of paths to sections of state. For example, ['user.firstName', 'settings.showBanner']

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should return user from application state', testExample(() => {
    return [
      [null, actions.getState(['user'])],
      [{ id: '123', username: 'foo' }, success({ id: '123', username: 'foo' })]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example () {
  const user = yield actions.getState(['user'])
  return user
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
run(handlers, example).then((user) => {
  user.id === 'abc' //  true, if the user has an `id` of 'abc' 
})

Returns Object an action of type getState.

setState

src/actions/universal/state.js:76-81

Creates a setState action. yield a setState to set application state.

Parameters

  • payload Object? An object that will be mergeed into the application state.

Examples

//  Test It 
const { testIt } = require('effects-as-data/test')
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
const testExample = testIt(example)
 
describe('example()', () => {
  it('should set a user on the application state', testExample(() => {
    const user = { user: '123' }
    return [
      [user, actions.setState({ user })],
      [null, success()]
    ]
  }))
})
//  Write It 
const { actions } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
function * example (user) {
  const result = yield actions.setState({ user })
  return result
}
//  Run It 
const { handlers, run } = require('effects-as-data/universal') //  also available in require('effects-as-data/node') 
 
const user = { id: '123', username: 'foo' }
run(handlers, example, user).then((result) => {
  result.success === true //  true, and `user` should be available on the application state using `actions.getState(['user'])` 
})

Returns Object an action of type setState.