browser_memory_allocations_01.js

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/* Any copyright is dedicated to the Public Domain.

 * http://creativecommons.org/publicdomain/zero/1.0/ */

"use strict";

add_task(async function () {

  const target = await addTabTarget("data:text/html;charset=utf-8,test-doc");

  const memory = await target.getFront("memory");

  await memory.attach();

  await memory.startRecordingAllocations();

  ok(true, "Can start recording allocations");

  // Allocate some objects.

  const [line1, line2, line3] = await SpecialPowers.spawn(

    gBrowser.selectedBrowser,

[],

    function () {

      // Use eval to ensure allocating the object in the page's compartment

      return content.eval(

        "(" +

          function () {

            let alloc1, alloc2, alloc3;

            /* eslint-disable max-nested-callbacks */

            (function outer() {

              (function middle() {

                (function inner() {

                  alloc1 = {};

                  alloc1.line = Error().lineNumber;

                  alloc2 = [];

                  alloc2.line = Error().lineNumber;

                  // eslint-disable-next-line new-parens

                  alloc3 = new (function () {})();

                  alloc3.line = Error().lineNumber;

                })();

              })();

            })();

            /* eslint-enable max-nested-callbacks */

            return [alloc1.line, alloc2.line, alloc3.line];

} +

          ")()"

);

);

  const response = await memory.getAllocations();

  await memory.stopRecordingAllocations();

  ok(true, "Can stop recording allocations");

  // Filter out allocations by library and test code, and get only the

  // allocations that occurred in our test case above.

  function isTestAllocation(alloc) {

    const frame = response.frames[alloc];

    return (

      frame &&

      frame.functionDisplayName === "inner" &&

      (frame.line === line1 || frame.line === line2 || frame.line === line3)

);

  const testAllocations = response.allocations.filter(isTestAllocation);

  Assert.greaterOrEqual(

    testAllocations.length,

3,

    "Should find our 3 test allocations (plus some allocations for the error " +

      "objects used to get line numbers)"

);

  // For each of the test case's allocations, ensure that the parent frame

  // indices are correct. Also test that we did get an allocation at each

  // line we expected (rather than a bunch on the first line and none on the

  // others, etc).

  const expectedLines = new Set([line1, line2, line3]);

  is(expectedLines.size, 3, "We are expecting 3 allocations");

  for (const alloc of testAllocations) {

    const innerFrame = response.frames[alloc];

    ok(innerFrame, "Should get the inner frame");

    is(innerFrame.functionDisplayName, "inner");

    expectedLines.delete(innerFrame.line);

    const middleFrame = response.frames[innerFrame.parent];

    ok(middleFrame, "Should get the middle frame");

    is(middleFrame.functionDisplayName, "middle");

    const outerFrame = response.frames[middleFrame.parent];

    ok(outerFrame, "Should get the outer frame");

    is(outerFrame.functionDisplayName, "outer");

    // Not going to test the rest of the frames because they are Task.jsm

    // and promise frames and it gets gross. Plus, I wouldn't want this test

    // to start failing if they changed their implementations in a way that

    // added or removed stack frames here.

  is(expectedLines.size, 0, "Should have found all the expected lines");

  await memory.detach();

  await target.destroy();

});