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Pinafore-Web-Client-Frontend/tests/spyDomListeners.js
Nolan Lawson cbbf5abd7a
test: test for DOM listener memory leaks (#1654)
* test: test for DOM listener memory leaks

* fix whitespace change, unintended
2019-11-23 23:42:22 -08:00

88 lines
2.3 KiB
JavaScript

import { ClientFunction as exec } from 'testcafe'
export const installDomListenerListener = exec(() => {
function eql (a, b) {
const aType = typeof a
const bType = typeof b
switch (aType) {
case 'boolean':
return bType === 'boolean' && b === a
case 'undefined':
return bType === 'undefined'
case 'object':
if (a === null) {
return b === null
}
if (b === null) {
return false
}
if (Object.keys(a).length !== Object.keys(b).length) {
return false
}
for (const key of Object.keys(a)) {
if (a[key] !== b[key]) {
return false
}
}
return true
}
return false
}
function spyAddListener (proto) {
const addEventListener = proto.addEventListener
proto.addEventListener = function (type, listener, options) {
if (!this.__listeners) {
this.__listeners = {}
}
if (!this.__listeners[type]) {
this.__listeners[type] = []
}
this.__listeners[type].push({ listener, options })
return addEventListener.apply(this, arguments)
}
}
function spyRemoveListener (proto) {
const removeEventListener = proto.removeEventListener
proto.removeEventListener = function (type, listener, options) {
if (this.__listeners && this.__listeners[type]) {
const arr = this.__listeners[type]
for (let i = arr.length - 1; i >= 0; i--) {
const { listener: otherListener, options: otherOptions } = arr[i]
if (listener === otherListener && eql(options, otherOptions)) {
arr.splice(i, 1)
}
}
}
return removeEventListener.apply(this, arguments)
}
}
function spy (proto) {
spyAddListener(proto)
spyRemoveListener(proto)
}
spy(Element.prototype)
spy(document)
spy(window)
})
export const getNumDomListeners = exec(() => {
function getNumListeners (obj) {
let sum = 0
if (obj.__listeners) {
for (const key of Object.keys(obj.__listeners)) {
sum += obj.__listeners[key].length
}
}
return sum
}
return [...document.querySelectorAll('*')]
.concat([window, document])
.map(getNumListeners)
.reduce((a, b) => a + b, 0)
})