1 files changed, 71 insertions, 0 deletions
diff --git a/devtools/client/inspector/changes/test/browser_changes_declaration_identical_rules.js b/devtools/client/inspector/changes/test/browser_changes_declaration_identical_rules.js
new file mode 100644
index 0000000000..08ac6d173d
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+++ b/devtools/client/inspector/changes/test/browser_changes_declaration_identical_rules.js
@@ -0,0 +1,71 @@
+/* Any copyright is dedicated to the Public Domain.
+ http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test tracking changes to CSS declarations in different stylesheets but in rules
+// with identical selectors.
+
+const TEST_URI = `
+  <style type='text/css'>
+    div {
+      color: red;
+    }
+  </style>
+  <style type='text/css'>
+    div {
+      font-size: 1em;
+    }
+  </style>
+  <div></div>
+`;
+
+add_task(async function () {
+  await addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
+  const { inspector, view: ruleView } = await openRuleView();
+  const { document: doc, store } = selectChangesView(inspector);
+
+  await selectNode("div", inspector);
+  const prop1 = getTextProperty(ruleView, 1, { "font-size": "1em" });
+  const prop2 = getTextProperty(ruleView, 2, { color: "red" });
+
+  let onTrackChange;
+
+  onTrackChange = waitForDispatch(store, "TRACK_CHANGE");
+  info("Disable the declaration in the first rule");
+  await togglePropStatus(ruleView, prop1);
+  info("Wait for change to be tracked");
+  await onTrackChange;
+
+  onTrackChange = waitForDispatch(store, "TRACK_CHANGE");
+  info("Disable the declaration in the second rule");
+  await togglePropStatus(ruleView, prop2);
+  info("Wait for change to be tracked");
+  await onTrackChange;
+
+  const removeDecl = getRemovedDeclarations(doc);
+  is(removeDecl.length, 2, "Two declarations tracked as removed");
+  // The last of the two matching rules shows up first in Rule view given that the
+  // specificity is the same. This is correct. If the properties were the same, the latest
+  // declaration would overwrite the first and thus show up on top.
+  is(
+    removeDecl[0].property,
+    "font-size",
+    "Correct property name for second declaration"
+  );
+  is(
+    removeDecl[0].value,
+    "1em",
+    "Correct property value for second declaration"
+  );
+  is(
+    removeDecl[1].property,
+    "color",
+    "Correct property name for first declaration"
+  );
+  is(
+    removeDecl[1].value,
+    "red",
+    "Correct property value for first declaration"
+  );
+});