1 files changed, 57 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-grid/subgrid/line-names-001.html b/testing/web-platform/tests/css/css-grid/subgrid/line-names-001.html
new file mode 100644
index 0000000000..69c300d864
--- /dev/null
+++ b/testing/web-platform/tests/css/css-grid/subgrid/line-names-001.html
@@ -0,0 +1,57 @@
+<!DOCTYPE HTML>
+<!--
+     Any copyright is dedicated to the Public Domain.
+     http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<html><head>
+  <meta charset="utf-8">
+  <title>CSS Grid Test: subgrid item using line names from outer grid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <link rel="help" href="https://drafts.csswg.org/css-grid-2">
+  <link rel="match" href="line-names-001-ref.html">
+  <style>
+html,body {
+  color:black; background-color:white; font:24px/1 monospace; padding:0; margin:0;
+}
+
+.grid {
+  display: grid;
+  grid: auto / [a] 50px 50px [a] 50px 50px [a];
+  padding: 20px 10px;
+}
+
+.subgrid {
+  display: grid;
+  grid: 50px / subgrid;
+  grid-column: span 3;
+}
+
+x { background: grey; }
+
+  </style>
+</head>
+<body>
+
+<div class="grid">
+  <div class="subgrid">
+    <x style="grid-column: span a / a -1"></x>
+  </div>
+</div>
+
+<script>
+  const expectedResults = [
+    "subgrid [] [] [] []",
+  ];
+  [...document.querySelectorAll('.subgrid')].forEach(function(subgrid, i) {
+    let actual = window.getComputedStyle(subgrid)['grid-template-columns'];
+    let expected = expectedResults[i];
+    if (actual != expected) {
+      let err = "Unexpected getComputedStyle value for subgrid " + i + " with className '" + subgrid.className + "':" +
+      " Actual: \"" + actual + "\", Expected: \"" + expected + "\"";
+      document.body.appendChild(document.createTextNode(err));
+    }
+  });
+</script>
+
+</body>
+</html>