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diff --git a/devtools/shared/heapsnapshot/tests/xpcshell/test_HeapAnalyses_getImmediatelyDominated_01.js b/devtools/shared/heapsnapshot/tests/xpcshell/test_HeapAnalyses_getImmediatelyDominated_01.js
new file mode 100644
index 0000000000..47860870cb
--- /dev/null
+++ b/devtools/shared/heapsnapshot/tests/xpcshell/test_HeapAnalyses_getImmediatelyDominated_01.js
@@ -0,0 +1,91 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test the HeapAnalyses{Client,Worker} "getImmediatelyDominated" request.
+
+const breakdown = {
+  by: "coarseType",
+  objects: { by: "count", count: true, bytes: true },
+  scripts: { by: "count", count: true, bytes: true },
+  strings: { by: "count", count: true, bytes: true },
+  other: { by: "count", count: true, bytes: true },
+  domNode: { by: "count", count: true, bytes: true },
+};
+
+add_task(async function () {
+  const client = new HeapAnalysesClient();
+
+  const snapshotFilePath = saveNewHeapSnapshot();
+  await client.readHeapSnapshot(snapshotFilePath);
+  const dominatorTreeId = await client.computeDominatorTree(snapshotFilePath);
+
+  const partialTree = await client.getDominatorTree({
+    dominatorTreeId,
+    breakdown,
+  });
+  ok(
+    !!partialTree.children.length,
+    "root should immediately dominate some nodes"
+  );
+
+  // First, test getting a subset of children available.
+  const response = await client.getImmediatelyDominated({
+    dominatorTreeId,
+    breakdown,
+    nodeId: partialTree.nodeId,
+    startIndex: 0,
+    maxCount: partialTree.children.length - 1,
+  });
+
+  ok(Array.isArray(response.nodes));
+  ok(response.nodes.every(node => node.parentId === partialTree.nodeId));
+  ok(response.moreChildrenAvailable);
+  equal(response.path.length, 1);
+  equal(response.path[0], partialTree.nodeId);
+
+  for (const node of response.nodes) {
+    equal(typeof node.shortestPaths, "object", "Should have shortest paths");
+    equal(
+      typeof node.shortestPaths.nodes,
+      "object",
+      "Should have shortest paths' nodes"
+    );
+    equal(
+      typeof node.shortestPaths.edges,
+      "object",
+      "Should have shortest paths' edges"
+    );
+  }
+
+  // Next, test getting a subset of children available.
+  const secondResponse = await client.getImmediatelyDominated({
+    dominatorTreeId,
+    breakdown,
+    nodeId: partialTree.nodeId,
+    startIndex: 0,
+    maxCount: Infinity,
+  });
+
+  ok(Array.isArray(secondResponse.nodes));
+  ok(secondResponse.nodes.every(node => node.parentId === partialTree.nodeId));
+  ok(!secondResponse.moreChildrenAvailable);
+  equal(secondResponse.path.length, 1);
+  equal(secondResponse.path[0], partialTree.nodeId);
+
+  for (const node of secondResponse.nodes) {
+    equal(typeof node.shortestPaths, "object", "Should have shortest paths");
+    equal(
+      typeof node.shortestPaths.nodes,
+      "object",
+      "Should have shortest paths' nodes"
+    );
+    equal(
+      typeof node.shortestPaths.edges,
+      "object",
+      "Should have shortest paths' edges"
+    );
+  }
+
+  client.destroy();
+});