test_grid_equality.html

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<!doctype html>

<html>

<head>

<meta charset="utf-8">

<script src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>

<link rel="stylesheet" href="chrome://mochikit/content/tests/SimpleTest/test.css" />

<style>

  #grid {

    display: grid;

    width: 100px;

    height: 100px;

  .cellOriginal {

    grid-column-end: span 2;

  .cellChanged {

    grid-column-end: span 5;

</style>

<script>

"use strict";

SimpleTest.waitForExplicitFinish();

function runTests() {

  const grid = document.getElementById("grid");

  const cell = document.getElementById("cell");

  const gridA = grid.getGridFragments()[0];

  // Check that grid fragments are equal across reflows.

  document.documentElement.offsetHeight; // Flush layout.

  const gridB = grid.getGridFragments()[0];

  is(gridB, gridA, "Grid fragments should be the same across reflows.");

  // Check that grid fragments are different when styles are different.

  cell.classList.replace("cellOriginal", "cellChanged");

  const gridC = grid.getGridFragments()[0];

  isnot(gridC, gridA, "Grids with different styles should have different fragments.");

  // Check that changing a grid to a matching style results in different fragments.

  cell.classList.replace("cellChanged", "cellOriginal");

  const gridD = grid.getGridFragments()[0];

  isnot(gridD, gridA, "Grids changed to the same styles should have different fragments.");

  SimpleTest.finish();

</script>

</head>

<body onLoad="runTests();">

<div id="grid">

  <div id="cell" class="cellOriginal"></div>

</div>

</body>

</html>