1 files changed, 64 insertions, 0 deletions
diff --git a/devtools/client/inspector/grids/test/browser_grids_grid-outline-updates-on-grid-change.js b/devtools/client/inspector/grids/test/browser_grids_grid-outline-updates-on-grid-change.js
new file mode 100644
index 0000000000..778217cc40
--- /dev/null
+++ b/devtools/client/inspector/grids/test/browser_grids_grid-outline-updates-on-grid-change.js
@@ -0,0 +1,64 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Tests that the grid outline does reflect the grid in the page even after the grid has
+// changed.
+
+const TEST_URI = `
+  <style>
+  .container {
+    display: grid;
+    grid-template-columns: repeat(2, 20vw);
+    grid-auto-rows: 20px;
+  }
+  </style>
+  <div class="container">
+    <div>item 1</div>
+    <div>item 2</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;
+
+  info("Clicking on the first checkbox to highlight the grid");
+  const checkbox = doc.querySelector("#grid-list input");
+
+  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-outline-cell", 2);
+
+  checkbox.click();
+
+  await onHighlighterShown;
+  await onCheckboxChange;
+  let elements = await onGridOutlineRendered;
+
+  info("Checking the grid outline is shown.");
+  is(elements.length, 2, "Grid outline is shown.");
+
+  info("Changing the grid in the page");
+  const onReflow = inspector.once("reflow-in-selected-target");
+  const onGridOutlineChanged = waitForDOM(doc, ".grid-outline-cell", 4);
+
+  await SpecialPowers.spawn(gBrowser.selectedBrowser, [], () => {
+    const div = content.document.createElement("div");
+    div.textContent = "item 3";
+    content.document.querySelector(".container").appendChild(div);
+  });
+
+  await onReflow;
+  elements = await onGridOutlineChanged;
+
+  info("Checking the grid outline is correct.");
+  is(elements.length, 4, "Grid outline was changed.");
+});