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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /css/css-cascade/layer-statement-before-import.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<title>CSS Cascade Layers: Empty layer statements before import rules</title>
<link rel="author" href="mailto:xiaochengh@chromium.org">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<div id="target"></div>
<div id="reference" style="color: green"></div>
<script>
// In all test cases, the 'color' property value of #target should be green.
const testCases = [
{
title: 'length and item',
style: `
@layer first, second;
@import url(data:text/css,);
@layer second {
#target { color: green; }
}
@layer first {
#target { color: red; }
}
`,
operations: function(sheet) {
assert_equals(sheet.cssRules.length, 4);
assert_equals(sheet.cssRules.item(0).cssText, '@layer first, second;');
assert_equals(sheet.cssRules.item(1).cssText, `@import url("data:text/css,");`);
assert_equals(sheet.cssRules.item(2).cssText,
'@layer second {\n #target { color: green; }\n}');
assert_equals(sheet.cssRules.item(3).cssText,
'@layer first {\n #target { color: red; }\n}');
}
},
{
title: 'insertRule before imports',
style: `
@import url(data:text/css,);
@layer second {
#target { color: green; }
}
@layer first {
#target { color: red; }
}
`,
operations: function(sheet) {
sheet.insertRule('@layer first, second', 0);
}
},
{
title: 'insertRule after imports',
style: `
@layer first, second;
@import url(data:text/css,);
@layer first {
#target { color: red; }
}
`,
operations: function(sheet) {
sheet.insertRule('@layer second { #target { color: green; } }', 2);
}
},
{
title: 'insert other rules to pre-import layer statements fails',
style: `
@layer first, second;
@import url(data:text/css,);
@layer second {
#target { color: green; }
}
@layer first {
#target { color: red; }
}
`,
operations: function(sheet) {
assert_throws_dom('HierarchyRequestError',
() => sheet.insertRule('#target { color: red !important; }', 0));
assert_throws_dom('HierarchyRequestError',
() => sheet.insertRule('#target { color: red !important; }', 1));
}
},
{
title: 'insert other rules before the first layer statement without imports',
style: `
@layer first, second;
@layer second {
#target { color: red !important; }
}
`,
operations: function(sheet) {
sheet.insertRule(`@layer first {
#target { color: green !important; }
}`, 0);
}
},
{
title: 'deleteRule before imports',
style: `
@layer second, first;
@import url(data:text/css,);
@layer first {
#target { color: red; }
}
@layer second {
#target { color: green; }
}
`,
operations: function(sheet) {
sheet.deleteRule(0);
}
},
{
title: 'deleteRule after imports',
style: `
@layer first, second;
@import url(data:text/css,);
@layer second {
#target { color: green; }
}
@layer first {
#target { color: red; }
}
#target {
color: red;
}
`,
operations: function(sheet) {
sheet.deleteRule(4);
}
},
];
const target = document.getElementById('target');
const reference = document.getElementById('reference');
for (let testCase of testCases) {
promise_test(async t => {
let styleElement = document.createElement('style');
styleElement.textContent = testCase.style;
await new Promise(resolve => {
styleElement.onload = resolve;
styleElement.onerror = resolve;
document.head.append(styleElement);
});
let sheet = styleElement.sheet;
try {
testCase.operations(sheet);
assert_equals(getComputedStyle(target).color, getComputedStyle(reference).color);
} finally {
styleElement.remove();
}
}, testCase.title);
}
</script>