Jest Leak Detector

import LeakDetector from "jest-leak-detector";

const LeakDetector = require("jest-leak-detector");

import LeakDetector from "jest-leak-detector";

async function detectLeak() {
  let reference = { data: "some object" };
  
  // Create detector to monitor the object
  const detector = new LeakDetector(reference);
  
  // Check if object is still in memory (should be true)
  let isLeaking = await detector.isLeaking();
  console.log(isLeaking); // true
  
  // Remove reference
  reference = null;
  
  // Check again after nullifying reference (should be false)
  isLeaking = await detector.isLeaking();
  console.log(isLeaking); // false
}

class LeakDetector {
  /**
   * Creates a leak detector for monitoring object garbage collection
   * @param value - The object to monitor (cannot be a primitive value)
   * @param opt - Optional configuration for detection behavior
   * @throws TypeError if value is a primitive (undefined, null, boolean, number, string, symbol)
   */
  constructor(value: unknown, opt?: LeakDetectorOptions);

  /**
   * Checks if the monitored object is still in memory
   * Forces garbage collection and checks if the object is still referenced
   * @returns Promise resolving to true if object is still in memory, false if garbage collected
   */
  isLeaking(): Promise<boolean>;
}

// Monitor simple objects
const detector = new LeakDetector({ foo: "bar" });
const isLeaking = await detector.isLeaking();

// Monitor functions
const fn = () => console.log("test");
const fnDetector = new LeakDetector(fn);

// Monitor arrays
const arr = [1, 2, 3];
const arrDetector = new LeakDetector(arr);

// With configuration options
const detector = new LeakDetector(someObject, {
  shouldGenerateV8HeapSnapshot: false
});

interface LeakDetectorOptions {
  /**
   * Whether to generate V8 heap snapshots for more aggressive garbage collection
   * Heap snapshots provide more thorough GC but are slower to execute
   * @default true
   */
  shouldGenerateV8HeapSnapshot: boolean;
}

// These will throw TypeError
new LeakDetector(null);        // TypeError: Primitives cannot leak memory. You passed a object: <null>
new LeakDetector(42);          // TypeError: Primitives cannot leak memory. You passed a number: <42>
new LeakDetector("string");    // TypeError: Primitives cannot leak memory. You passed a string: <"string">
new LeakDetector(true);        // TypeError: Primitives cannot leak memory. You passed a boolean: <true>
new LeakDetector(undefined);   // TypeError: Primitives cannot leak memory. You passed a undefined: <undefined>
new LeakDetector(Symbol());    // TypeError: Primitives cannot leak memory. You passed a symbol: <Symbol()>