jest-angular-memory-leak-example

Simple zone.js + jsdom memory leak example

This repo was created for angular/angular#24048 investigation

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Run npm install firstly

Run npm test

> jest --runInBand --logHeapUsage

 PASS  __tests__/test8.spec.js (44 MB heap size)
 PASS  __tests__/test11.spec.js (47 MB heap size)
 PASS  __tests__/test13.spec.js (50 MB heap size)
 PASS  __tests__/test17.spec.js (52 MB heap size)
 PASS  __tests__/test20.spec.js (55 MB heap size)
 PASS  __tests__/test16.spec.js (58 MB heap size)
 PASS  __tests__/test19.spec.js (62 MB heap size)
 PASS  __tests__/test6.spec.js (65 MB heap size)
 PASS  __tests__/test1.spec.js (68 MB heap size)
 PASS  __tests__/test24.spec.js (72 MB heap size)
 PASS  __tests__/test18.spec.js (75 MB heap size)
 PASS  __tests__/test23.spec.js (78 MB heap size)
 PASS  __tests__/test7.spec.js (81 MB heap size)
 PASS  __tests__/test21.spec.js (84 MB heap size)
 PASS  __tests__/test9.spec.js (88 MB heap size)
 PASS  __tests__/test15.spec.js (91 MB heap size)
 PASS  __tests__/test12.spec.js (94 MB heap size)
 PASS  __tests__/test10.spec.js (98 MB heap size)
 PASS  __tests__/test5.spec.js (101 MB heap size)
 PASS  __tests__/test25.spec.js (104 MB heap size)
 PASS  __tests__/test4.spec.js (107 MB heap size)
 PASS  __tests__/test2.spec.js (111 MB heap size)
 PASS  __tests__/test22.spec.js (114 MB heap size)
 PASS  __tests__/test14.spec.js (117 MB heap size)
 PASS  __tests__/test3.spec.js (120 MB heap size)

Test Suites: 25 passed, 25 total
Tests:       25 passed, 25 total
Snapshots:   0 total
Time:        4.07s
Ran all test suites.

As you can see there is steady heap usage increase

Run npm test -- --detectLeaks

● Test suite failed to run

    EXPERIMENTAL FEATURE!
    Your test suite is leaking memory. Please ensure all references are cleaned.

    There is a number of things that can leak memory:
      - Async operations that have not finished (e.g. fs.readFile).
      - Timers not properly mocked (e.g. setInterval, setTimeout).
      - Keeping references to the global scope.

      at node_modules/jest/node_modules/jest-cli/build/test_scheduler.js:264:22

As you can see jest reports memory leaks

Comment/remove require('zone.js/dist/zone.js'); in setupJest.js and run npm test

> jest --runInBand --logHeapUsage

 PASS  __tests__/test8.spec.js (50 MB heap size)
 PASS  __tests__/test1.spec.js (46 MB heap size)
 PASS  __tests__/test19.spec.js (45 MB heap size)
 PASS  __tests__/test17.spec.js (44 MB heap size)
 PASS  __tests__/test20.spec.js (43 MB heap size)
 PASS  __tests__/test13.spec.js (43 MB heap size)
 PASS  __tests__/test11.spec.js (43 MB heap size)
 PASS  __tests__/test22.spec.js (43 MB heap size)
 PASS  __tests__/test18.spec.js (44 MB heap size)
 PASS  __tests__/test6.spec.js (43 MB heap size)
 PASS  __tests__/test2.spec.js (44 MB heap size)
 PASS  __tests__/test25.spec.js (43 MB heap size)
 PASS  __tests__/test16.spec.js (44 MB heap size)
 PASS  __tests__/test9.spec.js (44 MB heap size)
 PASS  __tests__/test7.spec.js (44 MB heap size)
 PASS  __tests__/test21.spec.js (44 MB heap size)
 PASS  __tests__/test4.spec.js (43 MB heap size)
 PASS  __tests__/test24.spec.js (44 MB heap size)
 PASS  __tests__/test14.spec.js (44 MB heap size)
 PASS  __tests__/test10.spec.js (44 MB heap size)
 PASS  __tests__/test3.spec.js (44 MB heap size)
 PASS  __tests__/test23.spec.js (43 MB heap size)
 PASS  __tests__/test5.spec.js (44 MB heap size)
 PASS  __tests__/test15.spec.js (44 MB heap size)
 PASS  __tests__/test12.spec.js (44 MB heap size)

Test Suites: 25 passed, 25 total
Tests:       25 passed, 25 total
Snapshots:   0 total
Time:        2.922s
Ran all test suites.

As you can see there is NO steady heap usage increase