mithril-query

Query mithril virtual dom for testing purposes

Installation

npm install mithril-query --save-dev

Setup

In order to run tests in mithril 2.x we need to do some dom-mocking for the renderer. mithril-query will try to do this mocking for you, if it can't find the required globals, but this might not work properly due to module loading order. If you load mithril-query before everything else it should work as expected.

In any other case, this can be done manually by calling the ensureGlobals helper upfront (e. G. by adding if into a 'setup' file in your 'mocha' tests).

require('mithril-query').ensureGlobals()

Changes from version 3.x to 4.x

Root state access

... is gone, since mithril does not provide a way to access it

Booleans

... are now rendered as empty strings, like mithril does, because, well, mithril renders

Lifecycles

... are now fully supported, including synthetic DOM elements 🎉

find/first

... are now returning DOM elements instead of vdom nodes.

Custom events

... aren't supported anymore. Feel free to file a ticket, if you want them back.

Usage

You can run this tests server side or use browserify and run them in browsers.

const m = require('mithril')

module.exports = {
  view: function() {
    return m('div', [
      m('span', 'spanContent'),
      m('#fooId', 'fooContent'),
      m('.barClass', 'barContent'),
    ])
  },
}

/* eslint-env mocha */
const mq = require('mithril-query')
const simpleModule = require('./simple')

describe('simple module', function() {
  it('should generate appropriate output', function() {
    var output = mq(simpleModule)
    output.should.have('span')
    output.should.have('div > span')
    output.should.have('#fooId')
    output.should.have('.barClass')
    output.should.have(':contains(barContent)')
    output.should.contain('barContent')
  })
})

Run the test with

mocha simple.test.js

API

Initialise

First call mithril-query with either a vnode or a component. You can call it with one extra argument which will be used as attrs in the component case.

var mq = require('mithril-query')

// plain vnode
var out = mq(m('div'))

// object component
var myComponent = {
  view: function({ attrs }) {
    return m('div', attrs.text)
  },
}
var out = mq(myComponent, { text: 'huhu' })

// closure component
function myComponent() {
  return {
    view: function({ attrs }) {
      return m('div', attrs.text)
    },
  }
}
var out = mq(myComponent, { text: 'huhu' })

Query API

As you can see mq returns an out-Object which has the following test-API.

• out.first(selector) – Returns the first element that matches the selector (think document.querySelector).
• out.find(selector) – Returns all elements that match the selector (think document.querySelectorAll).
• out.has(selector) –  Returns true if any element in tree matches the selector, otherwise false.
• out.contains(string) – Returns true if any element in tree contains the string, otherwise false.
• out.log(selector, [logFN]) – Small helper function to log out what was selected. Mainly for debugging purposes. You can give an optional function which is called with the result. It defaults to HTML-Pretty-Printer (pretty-html-log] that logs the HTML-representation to stdout.

You can use these nice assertions. They throw errors if they're not fulfilled. See the example in the example folder.

• out.should.have([count], selector)

Throws if no element is found with selector. If count is given, it throws if count does not match.

• out.should.not.have(selector) – Throws if an element is found with selector.
• out.should.have.at.least(count, selector) – Throws if there a fewer than count elements matching the selector
• out.should.have([selector0, selector1, selector2]) – Throws there aren't at least one element for each selector.
• out.should.contain(string) – Throws if no element contains string.
• out.should.not.contain(string) - Throws if any element contains string.

Event triggering

It is also possible to trigger element events like onfocus and onclick and set values on <input>-fields. This allows you to write "integration tests" that run also on server side.

Attention: Currently there is no event bubbling supported.

• out.click(selector, [eventData]) – Runs onclick for first element that matches selector. Optional eventData is given as to the event constructor. eventData.redraw = false is respected.
• out.setValue(selector, string, [eventData]) – Runs oninput and onchange for first element that matches selector.
• out.trigger(selector, eventname, [eventData]) – General purpose event triggerer. Calls eventname on first matching element.

It also supports key events

• out.keydown(selector, keycode, [eventData]) – calls onkeydown with keycode
• out.keydown(selector, keyname, [eventData]) – calls onkeydown with keycode mapped from name. Mapping is done with this lib.

keyup, keypress are supported as well.

Auto "Redrawing"

Since mithril-query uses mithril on a fake DOM, auto rendering works as expected.

Example:

  // module code
  const component = {
    visible: true
    oninit({ state }) {
      state.toggleMe = () => (state.visible = !state.visible)
    },
    view({ state }) {
      return m(
        state.visible ? '.visible' : '.hidden',
        { onclick: state.toggleMe},
        'Test'
      )
    },
  }


  // actual test
  out = mq(component)
  out.should.have('.visible')
  out.click('.visible')
  out.should.not.have('.visible')
  out.should.have('.hidden')
  out.click('.hidden', { redraw: false })
  out.should.have('.hidden')

As you can see, you can prevent auto redraw by providing a redraw: false as last argument to click method.

You can also manually trigger redraw:

var out = mq(module)
out.should.have('.visible')
out.redraw()

helpers

If you need to access the rendered root element you can simply access it with

out.rootEl

onremove handling

To trigger onremove-handlers of all initialized components, just call out.onremove()