mozilla-central/testing/web-platform/tests/css/css-properties-values-api/unit-cycles.html

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<!DOCTYPE html>
<meta name="assert" content="This test verifies that reference cycles via units are detected" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script>
function register_property(name, syntax, inherits) {
CSS.registerProperty({
name: name,
syntax: syntax,
initialValue: '0px',
inherits: inherits
});
}
function register_length(name, inherits=false) {
register_property(name, '<length>', inherits);
}
function register_universal(name) {
register_property(name, '*', false);
}
register_length('--font-size-em');
register_length('--font-size-rem');
register_length('--font-size-ex');
register_length('--font-size-ch');
register_length('--font-size-px');
register_length('--font-size-lh');
register_length('--font-size-em-via-var');
register_length('--font-size-rem-via-var');
register_length('--font-size-ex-via-var');
register_length('--font-size-ch-via-var');
register_length('--font-size-em-inherited', true);
register_length('--font-size-ex-inherited', true);
register_length('--font-size-ch-inherited', true);
register_length('--line-height-lh');
register_length('--line-height-lh-via-var');
register_length('--line-height-lh-inherited', true);
register_universal('--font-size-em-universal');
register_universal('--font-size-rem-universal');
register_universal('--font-size-ex-universal');
register_universal('--font-size-ch-universal');
register_universal('--font-size-px-universal');
register_universal('--font-size-lh-universal');
</script>
<style>
:root {
--unregistered-em: 10em;
--unregistered-rem: 10rem;
--unregistered-ex: 10ex;
--unregistered-ch: 10ch;
--unregistered-lh: 10lh;
--unregistered-em-env: calc(10em + env(test, 0px));
--unregistered-rem-env: calc(10rem + env(test, 0px));
--unregistered-ex-env: calc(10ex + env(test, 0px));
--unregistered-ch-env: calc(10ch + env(test, 0px));
--unregistered-lh-env: calc(10lh + env(test, 0px));
}
:root, #target {
--font-size-em: 2em;
--font-size-rem: 2rem;
--font-size-ex: 2ex;
--font-size-ch: 2ch;
--font-size-px: 42px;
--font-size-lh: 2lh;
--line-height-lh: 2lh;
--font-size-em-via-var: var(--unregistered-em);
--font-size-rem-via-var: var(--unregistered-rem);
--font-size-ex-via-var: var(--unregistered-ex);
--font-size-ch-via-var: var(--unregistered-ch);
--line-height-lh-via-var: var(--unregistered-lh);
--font-size-em-universal: 2em;
--font-size-rem-universal: 2rem;
--font-size-ex-universal: 2ex;
--font-size-ch-universal: 2ch;
--font-size-px-universal: 42px;
--font-size-lh-universal: 2lh;
}
#parent {
--font-size-em-inherited: 4em;
--font-size-ex-inherited: 4ex;
--font-size-ch-inherited: 4ch;
--line-height-lh-inherited: 4lh;
}
#target {
font-size: 11px;
line-height: 13px;
}
</style>
<div id=parent>
<div id=target></div>
</div>
<div id=ref></div>
<script>
function unset_dimension(element = ref) {
element.style.fontSize = '';
element.style.marginBottom = '';
}
function compute_margin_bottom(dimension, element) {
try {
element.style.marginBottom = dimension;
return getComputedStyle(element).marginBottom;
} finally {
element.style.marginBottom = '';
}
}
// Compute a dimension (e.g. 1em) given a certain fontSize.
function compute_dimension(dimension, fontSize, element = ref) {
try {
element.style.fontSize = fontSize;
return compute_margin_bottom(dimension, element);
} finally {
element.style.fontSize = '';
}
}
function assert_property_equals(name, value, element = target) {
var computedStyle = getComputedStyle(element);
assert_equals(computedStyle.getPropertyValue(name), value);
}
let unsetFontSize = compute_dimension('1em', 'unset');
const unsetLineHeight = "normal";
add_result_callback(function(){
unset_dimension(target);
unset_dimension(document.documentElement);
});
test(function() {
// Unregistered variables behave as if they're copy & paste, so
// follow the regular font-relative size resolution.
const unregistered_variables = {
'unregistered-em': target.parentElement,
'unregistered-ex': target.parentElement,
'unregistered-ch': target.parentElement,
'unregistered-lh': target.parentElement,
'unregistered-rem': document.documentElement,
};
for (let variable in unregistered_variables) {
const e = unregistered_variables[variable];
const v = `var(--${variable})`;
target.style = `font-size: ${v};`;
assert_property_equals('font-size', compute_margin_bottom(v, e));
}
}, 'Font-dependent unregistered variables can be used in font-size');
test(function() {
const universal_variables = {
'font-size-em-universal': (v) => compute_dimension(v, 'unset', target),
'font-size-ex-universal': (v) => compute_dimension(v, 'unset', target),
'font-size-ch-universal': (v) => compute_dimension(v, 'unset', target),
'font-size-lh-universal': (v) => compute_margin_bottom('2lh', target.parentElement),
'font-size-rem-universal': (v) => compute_dimension(v, 'unset', target),
};
for (let variable in universal_variables) {
const v = `var(--${variable})`;
const expected = universal_variables[variable](v);
target.style = `font-size: ${v};`;
assert_property_equals('font-size', expected);
}
}, 'Registered universal variables referencing font-dependent units can be used in font-size');
test(function() {
// Unregistered variables behave as if they're copy & paste, so
// follow the regular font-relative size resolution.
const unregistered_variables = {
'unregistered-em-env': target.parentElement,
'unregistered-ex-env': target.parentElement,
'unregistered-ch-env': target.parentElement,
'unregistered-lh-env': target.parentElement,
'unregistered-rem-env': document.documentElement,
};
for (let variable in unregistered_variables) {
const e = unregistered_variables[variable];
const v = `var(--${variable})`;
target.style = `font-size: ${v};`;
assert_property_equals('font-size', compute_margin_bottom(v, e));
}
}, 'Font-dependent unregistered variables referencing env() can be used in font-size');
test(function() {
target.style = 'font-size: var(--font-size-px);';
assert_property_equals('font-size', '42px');
assert_property_equals('--font-size-px', '42px');
}, 'Non-font-dependent variables can be used in font-size');
test(function() {
target.style = 'font-size: var(--font-size-em);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-em', '0px');
}, 'Lengths with em units may not be referenced from font-size');
test(function() {
target.style = 'font-size: var(--font-size-ex);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-ex', '0px');
}, 'Lengths with ex units may not be referenced from font-size');
test(function() {
target.style = 'font-size: var(--font-size-ch);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-ch', '0px');
}, 'Lengths with ch units may not be referenced from font-size');
test(function() {
target.style = 'font-size: var(--font-size-lh);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-lh', '0px');
}, 'Lengths with lh units may not be referenced from font-size');
test(function() {
target.style = 'font-size: var(--font-size-rem);';
let expected = compute_dimension('2rem', 'unset', document.documentElement);
assert_property_equals('--font-size-rem', expected);
assert_property_equals('font-size', expected);
}, 'Lengths with rem units may be referenced from font-size on non-root element');
test(function() {
let root = document.documentElement;
root.style = 'font-size: var(--font-size-rem);';
assert_property_equals('font-size', unsetFontSize, root);
assert_property_equals('--font-size-rem', '0px', root);
}, 'Lengths with rem units may not be referenced from font-size on root element');
test(function() {
target.style = 'line-height: var(--line-height-lh);';
assert_property_equals('line-height', unsetLineHeight);
assert_property_equals('--line-height-lh', '0px');
}, 'Lengths with lh units may not be referenced from line-height');
test(function() {
target.style = 'font-size: var(--noexist, var(--font-size-em));';
assert_property_equals('font-size', unsetFontSize);
}, 'Fallback may not use font-relative units');
test(function() {
target.style = 'line-height: var(--noexist, var(--line-height-lh));';
assert_property_equals('line-height', unsetLineHeight);
}, 'Fallback may not use line-height-relative units');
test(function() {
target.style = 'font-size: var(--font-size-em, 42px);';
assert_property_equals('font-size', unsetFontSize);
}, 'Fallback not triggered while inside em unit cycle');
test(function() {
target.style = 'font-size: var(--font-size-ex, 42px);';
assert_property_equals('font-size', unsetFontSize);
}, 'Fallback not triggered while inside ex unit cycle');
test(function() {
target.style = 'font-size: var(--font-size-ch, 42px);';
assert_property_equals('font-size', unsetFontSize);
}, 'Fallback not triggered while inside ch unit cycle');
test(function() {
let root = document.documentElement;
root.style = 'font-size: var(--font-size-rem, 42px);';
assert_property_equals('font-size', unsetFontSize, root);
root.style = 'font-size: unset;';
}, 'Fallback not triggered while inside rem unit cycle on root element');
test(function() {
target.style = 'line-height: var(--line-height-lh, 42px);';
assert_property_equals('line-height', unsetLineHeight);
}, 'Fallback not triggered while inside lh unit cycle');
test(function() {
target.style = 'font-size: var(--font-size-em-via-var);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-em-via-var', '0px');
}, 'Lengths with em units are detected via var references');
test(function() {
target.style = 'font-size: var(--font-size-ex-via-var);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-ex-via-var', '0px');
}, 'Lengths with ex units are detected via var references');
test(function() {
target.style = 'font-size: var(--font-size-ch-via-var);';
assert_property_equals('font-size', unsetFontSize);
assert_property_equals('--font-size-ch-via-var', '0px');
}, 'Lengths with ch units are detected via var references');
test(function() {
let root = document.documentElement;
root.style = 'font-size: var(--font-size-rem-via-var);';
assert_property_equals('font-size', unsetFontSize, root);
assert_property_equals('--font-size-rem-via-var', '0px', root);
root.style = 'font-size: unset';
}, 'Lengths with rem units are detected via var references');
test(function() {
target.style = 'line-height: var(--line-height-lh-via-var);';
assert_property_equals('line-height', unsetLineHeight);
assert_property_equals('--line-height-lh-via-var', '0px');
}, 'Lengths with lh units are detected via var references');
test(function() {
let expected4em = compute_dimension('4em', 'unset');
target.style = 'font-size: var(--font-size-em-inherited);';
assert_property_equals('font-size', expected4em);
assert_property_equals('--font-size-em-inherited', expected4em);
}, 'Inherited lengths with em units may be used');
test(function() {
let expected4ex = compute_dimension('4ex', 'unset');
target.style = 'font-size: var(--font-size-ex-inherited);';
assert_property_equals('font-size', expected4ex);
assert_property_equals('--font-size-ex-inherited', expected4ex);
}, 'Inherited lengths with ex units may be used');
test(function() {
let expected4ch = compute_dimension('4ch', 'unset');
target.style = 'font-size: var(--font-size-ch-inherited);';
assert_property_equals('font-size', expected4ch);
assert_property_equals('--font-size-ch-inherited', expected4ch);
}, 'Inherited lengths with ch units may be used');
test(function() {
let expected4lh = compute_dimension('4lh', 'unset');
target.style = 'line-height: var(--line-height-lh-inherited);';
assert_property_equals('line-height', expected4lh);
assert_property_equals('--line-height-lh-inherited', expected4lh);
}, 'Inherited lengths with lh units may be used');
</script>