1 files changed, 60 insertions, 0 deletions
diff --git a/devtools/shared/heapsnapshot/tests/xpcshell/test_getCensusIndividuals_01.js b/devtools/shared/heapsnapshot/tests/xpcshell/test_getCensusIndividuals_01.js
new file mode 100644
index 0000000000..6963f3f33a
--- /dev/null
+++ b/devtools/shared/heapsnapshot/tests/xpcshell/test_getCensusIndividuals_01.js
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+"use strict";
+
+// Test basic functionality of `CensusUtils.getCensusIndividuals`.
+
+function run_test() {
+  const stack1 = saveStack(1);
+  const stack2 = saveStack(1);
+  const stack3 = saveStack(1);
+
+  const COUNT = { by: "count", count: true, bytes: true };
+  const INTERNAL_TYPE = { by: "internalType", then: COUNT };
+
+  const BREAKDOWN = {
+    by: "allocationStack",
+    then: INTERNAL_TYPE,
+    noStack: INTERNAL_TYPE,
+  };
+
+  const MOCK_SNAPSHOT = {
+    takeCensus: ({ breakdown }) => {
+      assertStructurallyEquivalent(
+        breakdown,
+        CensusUtils.countToBucketBreakdown(BREAKDOWN)
+      );
+
+      //                                DFS Index
+      // prettier-ignore
+      return new Map([               // 0
+        [stack1, {                   // 1
+          JSObject: [101, 102, 103], // 2
+          JSString: [111, 112, 113], // 3
+        }],
+        [stack2, {                   // 4
+          JSObject: [201, 202, 203], // 5
+          JSString: [211, 212, 213], // 6
+        }],
+        [stack3, {                   // 7
+          JSObject: [301, 302, 303], // 8
+          JSString: [311, 312, 313], // 9
+        }],
+        ["noStack", {                // 10
+          JSObject: [401, 402, 403], // 11
+          JSString: [411, 412, 413], // 12
+        }],
+      ]);
+    },
+  };
+
+  const INDICES = new Set([3, 5, 9]);
+
+  const EXPECTED = new Set([111, 112, 113, 201, 202, 203, 311, 312, 313]);
+
+  const actual = new Set(
+    CensusUtils.getCensusIndividuals(INDICES, BREAKDOWN, MOCK_SNAPSHOT)
+  );
+
+  assertStructurallyEquivalent(EXPECTED, actual);
+}