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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/**
* Contains a limited number of testing functions that are commonly used in a
* wide variety of situations, for example waiting for an event loop tick or an
* observer notification.
*
* More complex functions are likely to belong to a separate test-only module.
* Examples include Assert.jsm for generic assertions, FileTestUtils.jsm to work
* with local files and their contents, and BrowserTestUtils.jsm to work with
* browser windows and tabs.
*
* Individual components also offer testing functions to other components, for
* example LoginTestUtils.jsm.
*/
"use strict";
var EXPORTED_SYMBOLS = ["TestUtils"];
const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
const { setTimeout } = ChromeUtils.import("resource://gre/modules/Timer.jsm");
var TestUtils = {
executeSoon(callbackFn) {
Services.tm.dispatchToMainThread(callbackFn);
},
waitForTick() {
return new Promise(resolve => this.executeSoon(resolve));
},
/**
* Waits for the specified topic to be observed.
*
* @param {string} topic
* The topic to observe.
* @param {function} checkFn [optional]
* Called with (subject, data) as arguments, should return true if the
* notification is the expected one, or false if it should be ignored
* and listening should continue. If not specified, the first
* notification for the specified topic resolves the returned promise.
*
* @note Because this function is intended for testing, any error in checkFn
* will cause the returned promise to be rejected instead of waiting for
* the next notification, since this is probably a bug in the test.
*
* @return {Promise}
* @resolves The array [subject, data] from the observed notification.
*/
topicObserved(topic, checkFn) {
return new Promise((resolve, reject) => {
Services.obs.addObserver(function observer(subject, topic, data) {
try {
if (checkFn && !checkFn(subject, data)) {
return;
}
Services.obs.removeObserver(observer, topic);
resolve([subject, data]);
} catch (ex) {
Services.obs.removeObserver(observer, topic);
reject(ex);
}
}, topic);
});
},
/**
* Waits for the specified preference to be change.
*
* @param {string} prefName
* The pref to observe.
* @param {function} checkFn [optional]
* Called with the new preference value as argument, should return true if the
* notification is the expected one, or false if it should be ignored
* and listening should continue. If not specified, the first
* notification for the specified topic resolves the returned promise.
*
* @note Because this function is intended for testing, any error in checkFn
* will cause the returned promise to be rejected instead of waiting for
* the next notification, since this is probably a bug in the test.
*
* @return {Promise}
* @resolves The value of the preference.
*/
waitForPrefChange(prefName, checkFn) {
return new Promise((resolve, reject) => {
Services.prefs.addObserver(prefName, function observer(
subject,
topic,
data
) {
try {
let prefValue = null;
switch (Services.prefs.getPrefType(prefName)) {
case Services.prefs.PREF_STRING:
prefValue = Services.prefs.getStringPref(prefName);
break;
case Services.prefs.PREF_INT:
prefValue = Services.prefs.getIntPref(prefName);
break;
case Services.prefs.PREF_BOOL:
prefValue = Services.prefs.getBoolPref(prefName);
break;
}
if (checkFn && !checkFn(prefValue)) {
return;
}
Services.prefs.removeObserver(prefName, observer);
resolve(prefValue);
} catch (ex) {
Services.prefs.removeObserver(prefName, observer);
reject(ex);
}
});
});
},
/**
* Takes a screenshot of an area and returns it as a data URL.
*
* @param eltOrRect
* The DOM node or rect ({left, top, width, height}) to screenshot.
* @param win
* The current window.
*/
screenshotArea(eltOrRect, win) {
if (Element.isInstance(eltOrRect)) {
eltOrRect = eltOrRect.getBoundingClientRect();
}
let { left, top, width, height } = eltOrRect;
let canvas = win.document.createElementNS(
"http://www.w3.org/1999/xhtml",
"canvas"
);
let ctx = canvas.getContext("2d");
let ratio = win.devicePixelRatio;
canvas.width = width * ratio;
canvas.height = height * ratio;
ctx.scale(ratio, ratio);
ctx.drawWindow(win, left, top, width, height, "#fff");
return canvas.toDataURL();
},
/**
* Will poll a condition function until it returns true.
*
* @param condition
* A condition function that must return true or false. If the
* condition ever throws, this is also treated as a false. The
* function can be an async function.
* @param interval
* The time interval to poll the condition function. Defaults
* to 100ms.
* @param attempts
* The number of times to poll before giving up and rejecting
* if the condition has not yet returned true. Defaults to 50
* (~5 seconds for 100ms intervals)
* @return Promise
* Resolves with the return value of the condition function.
* Rejects if timeout is exceeded or condition ever throws.
*
* NOTE: This is intentionally not using setInterval, using setTimeout
* instead. setInterval is not promise-safe.
*/
waitForCondition(condition, msg, interval = 100, maxTries = 50) {
return new Promise((resolve, reject) => {
let tries = 0;
async function tryOnce() {
if (tries >= maxTries) {
msg += ` - timed out after ${maxTries} tries.`;
reject(msg);
return;
}
let conditionPassed = false;
try {
conditionPassed = await condition();
} catch (e) {
msg += ` - threw exception: ${e}`;
reject(msg);
return;
}
if (conditionPassed) {
resolve(conditionPassed);
return;
}
tries++;
setTimeout(tryOnce, interval);
}
// FIXME(bug 1596165): This could be a direct call, ideally.
setTimeout(tryOnce, interval);
});
},
shuffle(array) {
let results = [];
for (let i = 0; i < array.length; ++i) {
let randomIndex = Math.floor(Math.random() * (i + 1));
results[i] = results[randomIndex];
results[randomIndex] = array[i];
}
return results;
},
};
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