1 files changed, 150 insertions, 0 deletions
diff --git a/devtools/shared/heapsnapshot/tests/xpcshell/test_DominatorTreeNode_partialTraversal_01.js b/devtools/shared/heapsnapshot/tests/xpcshell/test_DominatorTreeNode_partialTraversal_01.js
new file mode 100644
index 0000000000..6da0587f57
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+++ b/devtools/shared/heapsnapshot/tests/xpcshell/test_DominatorTreeNode_partialTraversal_01.js
@@ -0,0 +1,150 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test that we correctly set `moreChildrenAvailable` when doing a partial
+// traversal of a dominator tree to create the initial incrementally loaded
+// `DominatorTreeNode` tree.
+
+// `tree` maps parent to children:
+//
+// 100
+//   |- 200
+//   |    |- 500
+//   |    |- 600
+//   |    `- 700
+//   |- 300
+//   |    |- 800
+//   |    |- 900
+//   `- 400
+//        |- 1000
+//        |- 1100
+//        `- 1200
+const tree = new Map([
+  [100, [200, 300, 400]],
+  [200, [500, 600, 700]],
+  [300, [800, 900]],
+  [400, [1000, 1100, 1200]],
+]);
+
+const mockDominatorTree = {
+  root: 100,
+  getRetainedSize: _ => 10,
+  getImmediatelyDominated: id => (tree.get(id) || []).slice(),
+};
+
+const mockSnapshot = {
+  describeNode: _ => ({
+    objects: { count: 0, bytes: 0 },
+    strings: { count: 0, bytes: 0 },
+    scripts: { count: 0, bytes: 0 },
+    other: { SomeType: { count: 1, bytes: 10 } },
+    domNode: { count: 0, bytes: 0 },
+  }),
+};
+
+const breakdown = {
+  by: "coarseType",
+  objects: { by: "count", count: true, bytes: true },
+  strings: { by: "count", count: true, bytes: true },
+  scripts: { by: "count", count: true, bytes: true },
+  other: {
+    by: "internalType",
+    then: { by: "count", count: true, bytes: true },
+  },
+  domNode: { by: "count", count: true, bytes: true },
+};
+
+const expected = {
+  nodeId: 100,
+  label: ["other", "SomeType"],
+  shallowSize: 10,
+  retainedSize: 10,
+  shortestPaths: undefined,
+  children: [
+    {
+      nodeId: 200,
+      label: ["other", "SomeType"],
+      shallowSize: 10,
+      retainedSize: 10,
+      parentId: 100,
+      shortestPaths: undefined,
+      children: [
+        {
+          nodeId: 500,
+          label: ["other", "SomeType"],
+          shallowSize: 10,
+          retainedSize: 10,
+          parentId: 200,
+          moreChildrenAvailable: false,
+          shortestPaths: undefined,
+          children: undefined,
+        },
+        {
+          nodeId: 600,
+          label: ["other", "SomeType"],
+          shallowSize: 10,
+          retainedSize: 10,
+          parentId: 200,
+          moreChildrenAvailable: false,
+          shortestPaths: undefined,
+          children: undefined,
+        },
+      ],
+      moreChildrenAvailable: true,
+    },
+    {
+      nodeId: 300,
+      label: ["other", "SomeType"],
+      shallowSize: 10,
+      retainedSize: 10,
+      parentId: 100,
+      shortestPaths: undefined,
+      children: [
+        {
+          nodeId: 800,
+          label: ["other", "SomeType"],
+          shallowSize: 10,
+          retainedSize: 10,
+          parentId: 300,
+          moreChildrenAvailable: false,
+          shortestPaths: undefined,
+          children: undefined,
+        },
+        {
+          nodeId: 900,
+          label: ["other", "SomeType"],
+          shallowSize: 10,
+          retainedSize: 10,
+          parentId: 300,
+          moreChildrenAvailable: false,
+          shortestPaths: undefined,
+          children: undefined,
+        },
+      ],
+      moreChildrenAvailable: false,
+    },
+  ],
+  moreChildrenAvailable: true,
+  parentId: undefined,
+};
+
+function run_test() {
+  // Traverse the whole depth of the test tree, but one short of the number of
+  // siblings. This will exercise the moreChildrenAvailable handling for
+  // siblings.
+  const actual = DominatorTreeNode.partialTraversal(
+    mockDominatorTree,
+    mockSnapshot,
+    breakdown,
+    // maxDepth
+    4,
+    // siblings
+    2
+  );
+
+  dumpn("Expected = " + JSON.stringify(expected, null, 2));
+  dumpn("Actual = " + JSON.stringify(actual, null, 2));
+
+  assertStructurallyEquivalent(expected, actual);
+}