1 files changed, 51 insertions, 0 deletions
diff --git a/devtools/client/inspector/grids/test/browser_grids_grid-outline-selected-grid.js b/devtools/client/inspector/grids/test/browser_grids_grid-outline-selected-grid.js
new file mode 100644
index 0000000000..ada2a635e4
--- /dev/null
+++ b/devtools/client/inspector/grids/test/browser_grids_grid-outline-selected-grid.js
@@ -0,0 +1,51 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests that the grid outline is shown when a grid container is selected.
+
+const TEST_URI = `
+  <style type='text/css'>
+    #grid {
+      display: grid;
+    }
+  </style>
+  <div id="grid">
+    <div id="cella">Cell A</div>
+    <div id="cellb">Cell B</div>
+    <div id="cellc">Cell C</div>
+  </div>
+`;
+
+add_task(async function () {
+  await addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
+
+  const { inspector, gridInspector } = await openLayoutView();
+  const { document: doc } = gridInspector;
+  const { highlighters, store } = inspector;
+
+  const gridList = doc.getElementById("grid-list");
+  const checkbox = gridList.children[0].querySelector("input");
+
+  info("Checking the initial state of the Grid Inspector.");
+  ok(
+    !doc.getElementById("grid-outline-container"),
+    "There should be no grid outline shown."
+  );
+
+  info("Toggling ON the CSS grid highlighter from the layout panel.");
+  const onHighlighterShown = highlighters.once("grid-highlighter-shown");
+  const onCheckboxChange = waitUntilState(
+    store,
+    state => state.grids.length == 1 && state.grids[0].highlighted
+  );
+  const onGridOutlineRendered = waitForDOM(doc, "#grid-cell-group rect", 3);
+  checkbox.click();
+  await onHighlighterShown;
+  await onCheckboxChange;
+  const elements = await onGridOutlineRendered;
+
+  info("Checking the grid outline is shown.");
+  is(elements.length, 3, "Grid outline is shown.");
+});