jest-leak-detector

jest-leak-detector

Module for verifying whether an object has been garbage collected or not.

Internally creates a weak reference to the object, and forces garbage collection to happen. If the reference is gone, it meant no one else was pointing to the object.

Example

(async function () {
  let reference = {};
  let isLeaking;

  const detector = new LeakDetector(reference);

  // Reference is held in memory.
  isLeaking = await detector.isLeaking();
  console.log(isLeaking); // true

  // We destroy the only reference to the object.
  reference = null;

  // Reference is gone.
  isLeaking = await detector.isLeaking();
  console.log(isLeaking); // false
})();

Changelog

25.5.0

Features

• [@jest/globals] New package so Jest's globals can be explicitly imported (#9801)
• [jest-core] Show coverage of sources related to tests in changed files (#9769)
• [jest-runtime] Populate require.cache (#9841)

Fixes

• [*] Use graceful-fs directly in every package instead of relying on fs being monkey patched (#9443)
• [expect] Prints the Symbol name into the error message with a custom asymmetric matcher (#9888)
• [jest-circus, jest-jasmine2] Support older version of jest-runtime (#9903 & #9842)
• [@jest/environment] Make sure not to reference Jest types (#9875)
• [jest-message-util] Code frame printing should respect --noStackTrace flag (#9866)
• [jest-runtime] Support importing CJS from ESM using import statements (#9850)
• [jest-runtime] Support importing parallel dynamic imports (#9858)
• [jest-transform] Improve source map handling when instrumenting transformed code (#9811)

Chore & Maintenance

• [docs] Add an example for mocking non-default export class

Performance

• [jest-resolve] Update resolve to a version using native realpath, which is faster than the default JS implementation (#9872)
• [jest-resolve] Pass custom cached realpath function to resolve (#9873)
• [jest-runtime] Add teardown method to clear any caches when tests complete (#9906)
• [jest-runtime] Do not pass files required internally through transformation when loading them (#9900)
• [jest-runtime] Use Maps instead of object literals as cache holders (#9901)