1 files changed, 78 insertions, 0 deletions
diff --git a/devtools/server/tests/browser/browser_perf-samples-02.js b/devtools/server/tests/browser/browser_perf-samples-02.js
new file mode 100644
index 0000000000..a48ccdcece
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+++ b/devtools/server/tests/browser/browser_perf-samples-02.js
@@ -0,0 +1,78 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/**
+ * Tests if the retrieved profiler data samples always have a (root) node.
+ * If this ever changes, the |ThreadNode.prototype.insert| function in
+ * devtools/client/performance/modules/logic/tree-model.js will have to be changed.
+ */
+
+"use strict";
+
+// Time in ms
+const WAIT_TIME = 1000;
+
+add_task(async function() {
+  const target = await addTabTarget(MAIN_DOMAIN + "doc_perf.html");
+
+  const front = await target.getFront("performance");
+
+  const rec = await front.startRecording();
+  // allow the profiler module to sample some cpu activity
+  busyWait(WAIT_TIME);
+
+  await front.stopRecording(rec);
+  const profile = rec.getProfile();
+  let sampleCount = 0;
+
+  for (const thread of profile.threads) {
+    info("Checking thread: " + thread.name);
+
+    for (const sample of thread.samples.data) {
+      sampleCount++;
+
+      const stack = getInflatedStackLocations(thread, sample);
+      if (stack[0] != "(root)") {
+        ok(
+          false,
+          "The sample " + stack.toSource() + " doesn't have a root node."
+        );
+      }
+    }
+  }
+
+  ok(
+    sampleCount > 0,
+    "At least some samples have been iterated over, checking for root nodes."
+  );
+
+  await target.getFront("performance");
+  gBrowser.removeCurrentTab();
+});
+
+/**
+ * Inflate a particular sample's stack and return an array of strings.
+ */
+function getInflatedStackLocations(thread, sample) {
+  const stackTable = thread.stackTable;
+  const frameTable = thread.frameTable;
+  const stringTable = thread.stringTable;
+  const SAMPLE_STACK_SLOT = thread.samples.schema.stack;
+  const STACK_PREFIX_SLOT = stackTable.schema.prefix;
+  const STACK_FRAME_SLOT = stackTable.schema.frame;
+  const FRAME_LOCATION_SLOT = frameTable.schema.location;
+
+  // Build the stack from the raw data and accumulate the locations in
+  // an array.
+  let stackIndex = sample[SAMPLE_STACK_SLOT];
+  const locations = [];
+  while (stackIndex !== null) {
+    const stackEntry = stackTable.data[stackIndex];
+    const frame = frameTable.data[stackEntry[STACK_FRAME_SLOT]];
+    locations.push(stringTable[frame[FRAME_LOCATION_SLOT]]);
+    stackIndex = stackEntry[STACK_PREFIX_SLOT];
+  }
+
+  // The profiler tree is inverted, so reverse the array.
+  return locations.reverse();
+}