1 files changed, 137 insertions, 0 deletions
diff --git a/dom/heapsnapshot/tests/unit/test_census_diff_06.js b/dom/heapsnapshot/tests/unit/test_census_diff_06.js
new file mode 100644
index 000000000..430ff8c9c
--- /dev/null
+++ b/dom/heapsnapshot/tests/unit/test_census_diff_06.js
@@ -0,0 +1,137 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test diffing census reports of a "complex" and "realistic" breakdown.
+
+const BREAKDOWN = {
+  by: "coarseType",
+  objects: {
+    by: "allocationStack",
+    then: {
+      by: "objectClass",
+      then: { by: "count", count: false, bytes: true },
+      other: { by: "count", count: false, bytes: true }
+    },
+    noStack: {
+      by: "objectClass",
+      then: { by: "count", count: false, bytes: true },
+      other: { by: "count", count: false, bytes: true }
+    }
+  },
+  strings: {
+    by: "internalType",
+    then: { by: "count", count: false, bytes: true }
+  },
+  scripts: {
+    by: "internalType",
+    then: { by: "count", count: false, bytes: true }
+  },
+  other: {
+    by: "internalType",
+    then: { by: "count", count: false, bytes: true }
+  },
+};
+
+const stack1 = saveStack();
+const stack2 = saveStack();
+const stack3 = saveStack();
+
+const REPORT1 = {
+  objects: new Map([
+    [stack1, { Function: { bytes: 1 },
+               Object: { bytes: 2 },
+               other: { bytes: 0 },
+             }],
+    [stack2, { Array: { bytes: 3 },
+               Date: { bytes: 4 },
+               other: { bytes: 0 },
+             }],
+    ["noStack", { Object: { bytes: 3 }}],
+  ]),
+  strings: {
+    JSAtom: { bytes: 10 },
+    JSLinearString: { bytes: 5 },
+  },
+  scripts: {
+    JSScript: { bytes: 1 },
+    "js::jit::JitCode": { bytes: 2 },
+  },
+  other: {
+    "mozilla::dom::Thing": { bytes: 1 },
+  }
+};
+
+const REPORT2 = {
+  objects: new Map([
+    [stack2, { Array: { bytes: 1 },
+               Date: { bytes: 2 },
+               other: { bytes: 3 },
+             }],
+    [stack3, { Function: { bytes: 1 },
+               Object: { bytes: 2 },
+               other: { bytes: 0 },
+             }],
+    ["noStack", { Object: { bytes: 3 }}],
+  ]),
+  strings: {
+    JSAtom: { bytes: 5 },
+    JSLinearString: { bytes: 10 },
+  },
+  scripts: {
+    JSScript: { bytes: 2 },
+    "js::LazyScript": { bytes: 42 },
+    "js::jit::JitCode": { bytes: 1 },
+  },
+  other: {
+    "mozilla::dom::OtherThing": { bytes: 1 },
+  }
+};
+
+const EXPECTED = {
+  "objects": new Map([
+    [stack1, { Function: { bytes: -1 },
+               Object: { bytes: -2 },
+               other: { bytes: 0 },
+             }],
+    [stack2, { Array: { bytes: -2 },
+               Date: { bytes: -2 },
+               other: { bytes: 3 },
+             }],
+    [stack3, { Function: { bytes: 1 },
+               Object: { bytes: 2 },
+               other: { bytes: 0 },
+             }],
+    ["noStack", { Object: { bytes: 0 }}],
+  ]),
+  "scripts": {
+    "JSScript": {
+      "bytes": 1
+    },
+    "js::jit::JitCode": {
+      "bytes": -1
+    },
+    "js::LazyScript": {
+      "bytes": 42
+    }
+  },
+  "strings": {
+    "JSAtom": {
+      "bytes": -5
+    },
+    "JSLinearString": {
+      "bytes": 5
+    }
+  },
+  "other": {
+    "mozilla::dom::Thing": {
+      "bytes": -1
+    },
+    "mozilla::dom::OtherThing": {
+      "bytes": 1
+    }
+  }
+};
+
+function run_test() {
+  assertDiff(BREAKDOWN, REPORT1, REPORT2, EXPECTED);
+}