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<!DOCTYPE html>
<meta charset="UTF-8">
<title>CSS Values and Units Test: computed value of 'background-position' when specified with calc() function</title>
<link rel="author" title="Gérard Talbot" href="http://www.gtalbot.org/BrowserBugsSection/css21testsuite/">
<link rel="help" href="https://www.w3.org/TR/css-values-3/#calc-computed-value">
<meta content="This test verifies how 6 calc() functions are computed for 'background-position'." name="assert">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="target"></div>
<script>
function startTesting()
{
var targetElement = document.getElementById("target");
function verifyComputedStyle(property_name, initial_value, specified_value, expected_value)
{
test(function()
{
targetElement.style.setProperty(property_name, initial_value);
/*
The purpose of the initial_value is to act as a fallback
value in case the calc() function in the specified value
fails or in case it generates an invalid value. Since we
are running 6 consecutive tests on the same element,
then it is necessary to 'reset' its property to an
initial value.
*/
targetElement.style.setProperty(property_name, specified_value);
assert_equals(getComputedStyle(targetElement)[property_name], expected_value);
}, `testing ${property_name}: ${specified_value}`);
}
/* verifyComputedStyle(property_name, initial_value, specified_value, expected_value) */
verifyComputedStyle("background-position", "initial", "calc(2px + 3px) calc(4px + 5px)", "5px 9px");
verifyComputedStyle("background-position", "initial", "calc(18px - 7px) calc(19px - 7px)", "11px 12px");
verifyComputedStyle("background-position", "initial", "calc(4 * 5px) calc(6px * 4)", "20px 24px");
verifyComputedStyle("background-position", "initial", "calc(100px / 4) calc(119px / 7)", "25px 17px");
verifyComputedStyle("background-position", "initial", "calc(6px + 21%) calc(7em + 22%)", "calc(21% + 6px) calc(22% + 112px)");
/*
"
(...) background-position has layout-dependent behavior for
percentage values, and thus does not resolve percentages
until used-value time. Due to this, background-position
computation preserves the percentage in a calc(). (...)
"
https://www.w3.org/TR/css-values-3/#calc-computed-value
*/
verifyComputedStyle("background-position", "initial", "calc(-8px + 23%) calc(-9em + 24%)", "calc(23% - 8px) calc(24% - 144px)");
/* verifyComputedStyle(property_name, initial_value, specified_value, expected_value) */
}
startTesting();
</script>
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