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// Expected values. Format: [name, pref_off_value, pref_on_value]
var expected_values = [
[
"device-aspect-ratio",
screen.width + "/" + screen.height,
window.innerWidth + "/" + window.innerHeight,
],
["device-height", screen.height + "px", window.innerHeight + "px"],
["device-width", screen.width + "px", window.innerWidth + "px"],
];
// Create a line containing a CSS media query and a rule to set the bg color.
var mediaQueryCSSLine = function (key, val, color) {
return (
"@media (" +
key +
": " +
val +
") { #" +
key +
" { background-color: " +
color +
"; } }\n"
);
};
var green = "rgb(0, 128, 0)";
var blue = "rgb(0, 0, 255)";
// Set a pref value asynchronously, returning a promise that resolves
// when it succeeds.
var pushPref = function (key, value) {
return SpecialPowers.pushPrefEnv({ set: [[key, value]] });
};
// Set the resistFingerprinting pref to the given value, and then check that the background
// color has been updated properly as a result of re-evaluating the media queries.
var checkColorForPref = async function (setting, testDivs, expectedColor) {
await pushPref("privacy.resistFingerprinting", setting);
for (let div of testDivs) {
let color = window.getComputedStyle(div).backgroundColor;
is(color, expectedColor, "background for '" + div.id + "' is " + color);
}
};
var test = async function () {
// If the "off" and "on" expected values are the same, we can't actually
// test anything here. (Might this be the case on mobile?)
let skipTest = false;
for (let [key, offVal, onVal] of expected_values) {
if (offVal == onVal) {
todo(false, "Unable to test because '" + key + "' is invariant");
return;
}
}
let css =
".test { margin: 1em; padding: 1em; color: white; width: max-content; font: 2em monospace }\n";
// Create a test element for each of the media queries we're checking, and append the matching
// "on" and "off" media queries to the CSS.
let testDivs = [];
for (let [key, offVal, onVal] of expected_values) {
let div = document.createElement("div");
div.textContent = key;
div.setAttribute("class", "test");
div.setAttribute("id", key);
testDivs.push(div);
document.getElementById("display").appendChild(div);
css += mediaQueryCSSLine(key, onVal, "green");
css += mediaQueryCSSLine(key, offVal, "blue");
}
document.getElementById("test-css").textContent = css;
// Check that the test elements change color as expected when we flip the resistFingerprinting pref.
await checkColorForPref(true, testDivs, green);
await checkColorForPref(false, testDivs, blue);
await checkColorForPref(true, testDivs, green);
};