1 files changed, 74 insertions, 0 deletions
diff --git a/devtools/client/inspector/computed/test/browser_computed_shadow_host.js b/devtools/client/inspector/computed/test/browser_computed_shadow_host.js
new file mode 100644
index 0000000000..19562eb1ed
--- /dev/null
+++ b/devtools/client/inspector/computed/test/browser_computed_shadow_host.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+const {
+  PropertyView,
+} = require("resource://devtools/client/inspector/computed/computed.js");
+
+// Test matched selectors for a :host selector in the computed view.
+
+const SHADOW_DOM = `<style>
+  :host {
+    color: red;
+  }
+
+  .test-span {
+    color: blue;
+  }
+</style>
+<span class="test-span">test</span>`;
+
+const TEST_PAGE = `
+  <div id="host"></div>
+  <script>
+    const div = document.querySelector("div");
+    div.attachShadow({ mode: "open" }).innerHTML = \`${SHADOW_DOM}\`;
+  </script>`;
+
+const TEST_URI = `https://example.com/document-builder.sjs?html=${encodeURIComponent(
+  TEST_PAGE
+)}`;
+
+add_task(async function () {
+  await addTab(TEST_URI);
+  const { inspector, view } = await openComputedView();
+
+  {
+    await selectNode("#host", inspector);
+    const propertyView = await getPropertyViewWithSelectors(view, "color");
+    const selectors = propertyView.matchedSelectors.map(s => s.selector);
+    Assert.deepEqual(
+      selectors,
+      [":host", ":root"],
+      "host has the expected selectors for color"
+    );
+  }
+
+  {
+    const nodeFront = await getNodeFrontInShadowDom(
+      ".test-span",
+      "#host",
+      inspector
+    );
+    await selectNode(nodeFront, inspector);
+    const propertyView = await getPropertyViewWithSelectors(view, "color");
+    const selectors = propertyView.matchedSelectors.map(s => s.selector);
+    Assert.deepEqual(
+      selectors,
+      [".test-span", ":host", ":root"],
+      "shadow host child has the expected selectors for color"
+    );
+  }
+});
+
+async function getPropertyViewWithSelectors(view, property) {
+  const propertyView = new PropertyView(view, property);
+  propertyView.createListItemElement();
+  propertyView.matchedExpanded = true;
+
+  await propertyView.refreshMatchedSelectors();
+
+  return propertyView;
+}