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<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>VirtualizedList Tests</title>
<script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
<script src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
<link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
<link rel="stylesheet" href="chrome://global/skin/in-content/common.css">
<link rel="stylesheet" href="chrome://global/content/megalist/megalist.css">
<script type="module" src="chrome://global/content/megalist/VirtualizedList.mjs"></script>
</head>
<body>
<style>
</style>
<p id="display"></p>
<div id="content">
<virtualized-list></virtualized-list>
</div>
<pre id="test">
<script class="testbody" type="application/javascript">
const virtualizedList = document.querySelector("virtualized-list");
function dispatchScrollEvent(target, scrollY) {
target.scrollTop = scrollY;
virtualizedList.dispatchEvent(new Event('scroll'));
}
function updateVisibleItemBoundaries(visibleItemCount, value) {
if (value > visibleItemCount.max) {
visibleItemCount.max = value;
}
}
// Setup
virtualizedList.lineHeight = 64;
virtualizedList.lineCount = 1000;
virtualizedList.selectedIndex = 0;
virtualizedList.createLineElement = index => {
const lineElement = document.createElement("div");
lineElement.classList.add("line");
lineElement.textContent = `Row ${index}`;
return lineElement;
}
virtualizedList.style.display = "block";
virtualizedList.style.height = "300px";
virtualizedList.style.width = "500px";
/**
* Tests that the virtualized list renders expected number of items
*/
add_task(async function test_rebuildVisibleLines() {
let container = virtualizedList.querySelector(".lines-container");
let initialLines = container.querySelectorAll(".line");
// Get boundaries of visible item count as they are rendered.
let visibleItemsCount = {
min: initialLines.length,
max: initialLines.length,
};
is(
container.style.height,
`${virtualizedList.lineHeight * virtualizedList.lineCount}px`,
"VirtualizedList is correct height."
);
// Scroll down 800px
dispatchScrollEvent(virtualizedList, 800);
let newRenderedLines = container.querySelectorAll(".line");
updateVisibleItemBoundaries(visibleItemsCount, newRenderedLines.length);
let firstRow = container.querySelector(".line[data-index='0']");
ok(!firstRow, "The first row should be removed.");
// Scroll down another 800px
dispatchScrollEvent(virtualizedList, 800);
newRenderedLines = container.querySelectorAll(".line");
updateVisibleItemBoundaries(visibleItemsCount, newRenderedLines.length);
let thirdRow = container.querySelector(".line[data-index='2']");
ok(!thirdRow, "The third row should be removed.");
// Check that amount of visible lines is within boundaries. This is to
// ensure the list is keeping a range of rendered items and
// not increasing the element count in the DOM.
ok(
newRenderedLines.length >= visibleItemsCount.min &&
newRenderedLines.length <= visibleItemsCount.max,
"Virtual list is removing and adding lines as needed."
);
// Scroll back to top
dispatchScrollEvent(virtualizedList, 0);
newRenderedLines = container.querySelectorAll(".line");
updateVisibleItemBoundaries(visibleItemsCount, newRenderedLines.length);
firstRow = container.querySelector(".line[data-index='0']");
thirdRow = container.querySelector(".line[data-index='2']");
ok(firstRow, "The first row should be rendered again.");
ok(firstRow, "The third row should be rendered again.");
});
/**
* Tests that item selection is preserved when list is rebuilt
*/
add_task(async function test_updateLineSelection() {
let container = virtualizedList.querySelector(".lines-container");
let selectedLine = container.querySelector(".selected");
is(selectedLine.dataset.index, "0", "The correct line is selected");
// Scroll down 800px
dispatchScrollEvent(virtualizedList, 800);
selectedLine = container.querySelector(".selected");
ok(!selectedLine, "Selected line is not rendered because it's out of view");
is(virtualizedList.selectedIndex, 0, "Selected line is still preserved in list.");
// Scroll back to top
dispatchScrollEvent(virtualizedList, 0);
selectedLine = container.querySelector(".selected");
is(selectedLine.dataset.index, "0", "The same selected line is rendered.");
});
</script>
</pre>
</body>
</html>
|
