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<head>
<title>Shadow DOM: CSS Style Rule cascading</title>
<meta name="assert" content="Cascading order test for style rules from various shadow trees.">
<link rel="author" title="Takayoshi Kochi" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-scoping-1/#shadow-cascading">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
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<body>
<div id="log"></div>
<script>
// Taken from the example in
// https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Shadow-DOM-Cascade-Order.md
// https://github.com/w3c/webcomponents/issues/316
// https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Shadow-DOM-Cascade-Order-in-v1.md
// with element renamed and style rule location changed.
//
// <style>my-item { color: red; }</style>
// <my-list>
// <:shadow>
// <style>::slotted(my-item) { color: blue; }</style>
// <slot></slot>
// </:shadow>
// <my-item style="color: green;">
// <:shadow>
// <style>:host { color: yellow; }</style>
// <slot></slot>
// </:shadow>
// ITEM
// </my-item>
// </my-list>
//
// There are 4 possible style rules that applies to <my-item> above:
// 1. document-wide style
// 2. ::slotted style in the shadow in <my-list>
// 3. :host style in the shadow in <my-item>
// 4. inline style within <my-item> itself.
//
// It could be possible to nest many more shadow trees in <my-list>,
// but to prevent the number of combination explosion, such case is covered
// in another test file.
//
// So testing cases where 2 style rules are competing,
// 4C2 = 6 combinations exist, multiplied by 4, which is the possible
// combination of applying "!important" for the 2 style rules.
function createMyList(mode, slottedStyle, hostStyle, inlineStyle) {
var myList = document.createElement('my-list');
var root = myList.attachShadow({'mode': mode});
root.innerHTML = '<style>' + slottedStyle + '</style><slot></slot>';
var myItem = document.createElement('my-item');
if (inlineStyle !== '')
myItem.setAttribute('style', inlineStyle);
myList.appendChild(myItem);
var root2 = myItem.attachShadow({'mode': mode});
root2.innerHTML = '<style>' + hostStyle + '</style><slot></slot>';
myItem.appendChild(document.createTextNode('ITEM'));
return myList;
}
function testCascadingOrder(mode) {
// In all test cases, the rule specified as "color: green" should win.
var testCases = [
// [A] Cases between document, ::slotteed, :host, and inline
{
title: 'A1. document vs ::slotted, document rule should win',
documentStyle: 'my-item { color: green; }',
slottedStyle: '::slotted(my-item) { color: red; }',
hostStyle: '',
inlineStyle: ''
},
{
title: 'A2. document vs :host, document rule should win',
documentStyle: 'my-item { color: green; }',
slottedStyle: '',
hostStyle: ':host { color: red; }',
inlineStyle: ''
},
{
title: 'A3. document vs inline, inline rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle: '',
hostStyle: '',
inlineStyle: 'color: green;'
},
{
title: 'A4. ::slotted vs :host, earlier in tree-of-trees rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green; }',
hostStyle: ':host { color: red; }',
inlineStyle: ''
},
{
title: 'A5. ::slotted vs inline, inline rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: red; }',
hostStyle: '',
inlineStyle: 'color: green;'
},
{
title: 'A6. :host vs inline, inline rule should win',
documentStyle: '',
slottedStyle: '',
hostStyle: ':host { color: red; }',
inlineStyle: 'color: green;'
},
// [B] Stronger rule is still stronger with !important
{
title: 'B1. document with !important vs ::slotted, document rule should win',
documentStyle: 'my-item { color: green !important; }',
slottedStyle: '::slotted(my-item) { color: red; }',
hostStyle: '',
inlineStyle: ''
},
{
title: 'B2. document with !important vs :host, document rule should win',
documentStyle: 'my-item { color: green !important; }',
slottedStyle: '',
hostStyle: ':host { color: red; }',
inlineStyle: ''
},
{
title: 'B3. document vs inline with !important, inline rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle: '',
hostStyle: '',
inlineStyle: 'color: green !important;'
},
{
title: 'B4. ::slotted with !important vs :host, earlier in tree-of-trees rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: ':host { color: red; }',
inlineStyle: ''
},
{
title: 'B5. ::slotted vs inline with !important, inline rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: '',
inlineStyle: 'color: red;'
},
{
title: 'B6. :host vs inline with !important, inline rule should win',
documentStyle: '',
slottedStyle: '',
hostStyle: ':host { color: red; }',
inlineStyle: 'color: green !important;'
},
// [C] Weaker rule gets stronger with !important
{
title: 'C1. document vs ::slotted with !important, ::slotted rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: '',
inlineStyle: ''
},
{
title: 'C2. document vs :host with !important, :host rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle: '',
hostStyle: ':host { color: green !important; }',
inlineStyle: ''
},
{
title: 'C3. document with !important vs inline, document rule should win',
documentStyle: 'my-item { color: green !important; }',
slottedStyle: '',
hostStyle: '',
inlineStyle: 'color: red;'
},
{
title: 'C4. ::slotted vs :host with !important, later in tree-of-trees rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: ':host { color: red; }',
inlineStyle: ''
},
{
title: 'C5. ::slotted with !important vs inline, ::slotted rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: '',
inlineStyle: 'color: red;'
},
{
title: 'C6. :host with !important vs inline, :host rule should win',
documentStyle: '',
slottedStyle: '',
hostStyle: ':host { color: green !important; }',
inlineStyle: 'color: red;'
},
// [D] Cases between document, ::slotteed, :host, and inline, both with !important
{
title: 'D1. document vs ::slotted both with !important, ::slotted rule should win',
documentStyle: 'my-item { color: red !important; }',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: '',
inlineStyle: ''
},
{
title: 'D2. document vs :host both with !important, :host rule should win',
documentStyle: 'my-item { color: red !important; }',
slottedStyle: '',
hostStyle: ':host { color: green !important; }',
inlineStyle: ''
},
{
title: 'D3. document vs inline both with !important, inline rule should win',
documentStyle: 'my-item { color: red !important; }',
slottedStyle: '',
hostStyle: '',
inlineStyle: 'color: green !important;'
},
{
title: 'D4. ::slotted vs :host both with !important, later in tree-of-trees rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: red !important; }',
hostStyle: ':host { color: green !important; }',
inlineStyle: ''
},
{
title: 'D5. ::slotted vs inline both with !important, ::slotted rule should win',
documentStyle: '',
slottedStyle: '::slotted(my-item) { color: green !important; }',
hostStyle: '',
inlineStyle: 'color: red !important;'
},
{
title: 'D6. :host vs inline both with !important, :host rule should win',
documentStyle: '',
slottedStyle: '',
hostStyle: ':host { color: green !important; }',
inlineStyle: 'color: red !important;'
},
// [E] Putting all together
{
title: 'E1. all style applied, inline rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle: '::slotted(my-item) { color: blue; }',
hostStyle: ':host { color: yellow; }',
inlineStyle: 'color: green;'
},
{
title: 'E2. all styles with !important applied, rule in the last tree-of-trees should win',
documentStyle: 'my-item { color: red !important; }',
slottedStyle: '::slotted(my-item) { color: blue !important; }',
hostStyle: ':host { color: green !important; }',
inlineStyle: 'color: yellow !important;'
},
];
for (var i = 0; i < testCases.length; ++i) {
var testCase = testCases[i];
var documentStyle = document.createElement('style');
documentStyle.appendChild(document.createTextNode(testCase['documentStyle']));
document.head.appendChild(documentStyle);
var myList = createMyList(mode,
testCase['slottedStyle'], testCase['hostStyle'], testCase['inlineStyle']);
document.body.appendChild(myList);
test(function () {
var myItem = myList.querySelector('my-item');
assert_equals(window.getComputedStyle(myItem).color, 'rgb(0, 128, 0)',
testCase['title']);
}, testCase['title'] + ' for ' + mode + ' mode.');
myList.parentNode.removeChild(myList);
document.head.removeChild(documentStyle)
}
}
// Open or Closed should not make any difference in style application.
testCascadingOrder('open');
testCascadingOrder('closed');
// Taken from the example in
// https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Shadow-DOM-Cascade-Order.md
// https://github.com/w3c/webcomponents/issues/316
// https://github.com/w3c/webcomponents/blob/gh-pages/proposals/Shadow-DOM-Cascade-Order-in-v1.md
// with element renamed and style rule location changed.
//
// <style>my-item { color: red; }</style>
// <my-list>
// <:shadow>
// <style>::slotted(my-item) { color: blue; }</style>
// <div>
// <:shadow>
// <slot/>
// </:shadow>
// <slot/>
// </div>
// </:shadow>
// <my-item style="color: green;">
// <:shadow>
// <style>:host { color: yellow; }</style>
// <slot/>
// </:shadow>
// ITEM
// </my-item>
// </my-list>
//
// The difference from the example tree above is that <my-list> has 2 levels of
// shadow trees, each with ::slotted(my-list) style rules.
function createMyListWith2LevelShadow(mode, slottedStyle1, slottedStyle2, hostStyle) {
var myList = document.createElement('my-list');
var root = myList.attachShadow({'mode': mode});
root.innerHTML = '<style>' + slottedStyle1 + '</style><div><slot></slot></div>';
var div = root.querySelector('div');
var root2 = div.attachShadow({'mode': mode});
root2.innerHTML = '<style>' + slottedStyle2 + '</style><slot></slot>';
var myItem = document.createElement('my-item');
myList.appendChild(myItem);
var root3 = myItem.attachShadow({'mode': mode});
root3.innerHTML = '<style>' + hostStyle + '</style><slot></slot>';
myItem.appendChild(document.createTextNode('ITEM'));
return myList;
}
function testCascadingOrderWith2LevelShadow(mode) {
// In all test cases, the rule specified as "color: green" should win.
var testCases = [
{
title: 'F1. document vs others, document (the first rule in tree-of-trees order) rule should win',
documentStyle: 'my-item { color: green; }',
slottedStyle1: '::slotted(my-item) { color: red; }',
slottedStyle2: '::slotted(my-item) { color: red; }',
hostStyle: ':host { color: red; }',
},
{
title: 'F2. document with !important vs others, document rule should win',
documentStyle: 'my-item { color: green !important; }',
slottedStyle1: '::slotted(my-item) { color: red; }',
slottedStyle2: '::slotted(my-item) { color: red; }',
hostStyle: ':host { color: red; }',
},
{
title: 'F3. document vs ::slotted with !important, important rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle1: '::slotted(my-item) { color: green !important; }',
slottedStyle2: '::slotted(my-item) { color: red; }',
hostStyle: ':host { color: red; }',
},
{
title: 'F4. document vs ::slotted with !important, important rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle1: '::slotted(my-item) { color: red; }',
slottedStyle2: '::slotted(my-item) { color: green !important; }',
hostStyle: ':host { color: red; }',
},
{
title: 'F5. document vs :host with !important, important rule should win',
documentStyle: 'my-item { color: red; }',
slottedStyle1: '::slotted(my-item) { color: red; }',
slottedStyle2: '::slotted(my-item) { color: red; }',
hostStyle: ':host { color: green !important; }',
},
{
title: 'F6. all rules with !important, the last rule in tree-of-trees should win',
documentStyle: 'my-item { color: red !important; }',
slottedStyle1: '::slotted(my-item) { color: red !important; }',
slottedStyle2: '::slotted(my-item) { color: red !important; }',
hostStyle: ':host { color: green !important ; }',
}
];
for (var i = 0; i < testCases.length; ++i) {
var testCase = testCases[i];
var documentStyle = document.createElement('style');
documentStyle.appendChild(document.createTextNode(testCase['documentStyle']));
document.head.appendChild(documentStyle);
var myList = createMyListWith2LevelShadow(mode,
testCase['slottedStyle1'], testCase['slottedStyle2'], testCase['hostStyle']);
document.body.appendChild(myList);
test(function () {
var myItem = myList.querySelector('my-item');
assert_equals(window.getComputedStyle(myItem).color, 'rgb(0, 128, 0)',
testCase['title']);
}, testCase['title'] + ' for ' + mode + ' mode.');
myList.parentNode.removeChild(myList);
document.head.removeChild(documentStyle)
}
}
// Open or Closed should not make any difference in style application.
testCascadingOrderWith2LevelShadow('open');
testCascadingOrderWith2LevelShadow('closed');
</script>
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