1 files changed, 54 insertions, 0 deletions
diff --git a/dom/heapsnapshot/tests/unit/test_HeapAnalyses_takeCensusDiff_01.js b/dom/heapsnapshot/tests/unit/test_HeapAnalyses_takeCensusDiff_01.js
new file mode 100644
index 000000000..6f22cbad3
--- /dev/null
+++ b/dom/heapsnapshot/tests/unit/test_HeapAnalyses_takeCensusDiff_01.js
@@ -0,0 +1,54 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that the HeapAnalyses{Client,Worker} can take diffs between censuses.
+
+function run_test() {
+  run_next_test();
+}
+
+const BREAKDOWN = {
+  by: "objectClass",
+  then: { by: "count", count: true, bytes: false },
+  other: { by: "count", count: true, bytes: false },
+};
+
+add_task(function* () {
+  const client = new HeapAnalysesClient();
+
+  const markers = [allocationMarker()];
+
+  const firstSnapshotFilePath = saveNewHeapSnapshot();
+
+  // Allocate and hold an additional AllocationMarker object so we can see it in
+  // the next heap snapshot.
+  markers.push(allocationMarker());
+
+  const secondSnapshotFilePath = saveNewHeapSnapshot();
+
+  yield client.readHeapSnapshot(firstSnapshotFilePath);
+  yield client.readHeapSnapshot(secondSnapshotFilePath);
+  ok(true, "Should have read both heap snapshot files");
+
+  const { delta } = yield client.takeCensusDiff(firstSnapshotFilePath,
+                                                secondSnapshotFilePath,
+                                                { breakdown: BREAKDOWN });
+
+  equal(delta.AllocationMarker.count, 1,
+    "There exists one new AllocationMarker in the second heap snapshot");
+
+  const { delta: deltaTreeNode } = yield client.takeCensusDiff(firstSnapshotFilePath,
+                                                               secondSnapshotFilePath,
+                                                               { breakdown: BREAKDOWN },
+                                                               { asTreeNode: true });
+
+  // Have to manually set these because symbol properties aren't structured
+  // cloned.
+  delta[CensusUtils.basisTotalBytes] = deltaTreeNode.totalBytes;
+  delta[CensusUtils.basisTotalCount] = deltaTreeNode.totalCount;
+
+  compareCensusViewData(BREAKDOWN, delta, deltaTreeNode,
+    "Returning delta-census as a tree node represents same data as the report");
+
+  client.destroy();
+});