chore: fix latest compile TS and Node 20 workflow failures

.github/workflows/ci_main.yml

@@ -11,6 +11,8 @@ jobs:
   build:
     runs-on: ubuntu-latest
     strategy:
+      # Prevent GitHub from canceling all in-progress jobs when a matrix job fails
+      fail-fast: false
       matrix:
         node: ['18', '20']
 

packages/rxjs/package.json

@@ -61,7 +61,7 @@
   "scripts": {
     "lint": "eslint --ext=ts,js src spec spec-dtslint",
     "dtslint": "npm run lint && tsc -b ./src/tsconfig.types.json",
-    "test": "cross-env TS_NODE_PROJECT=tsconfig.mocha.json mocha --config spec/support/.mocharc.js \"spec/**/*-spec.ts\"",
+    "test": "cross-env TS_NODE_PROJECT=tsconfig.mocha.json node --expose-gc ../../node_modules/.bin/_mocha --config spec/support/.mocharc.js \"spec/**/*-spec.ts\"",
     "test:esm": "node spec/module-test-spec.mjs",
     "test:circular": "dependency-cruiser --validate .dependency-cruiser.json -x \"^node_modules\" dist/esm",
     "test:import": "node integration/import/runner.js",

packages/rxjs/spec/Subscriber-spec.ts

@@ -1,5 +1,5 @@
 import { expect } from 'chai';
-import type { Observer} from 'rxjs';
+import type { Observer } from 'rxjs';
 import { Subscriber, Observable, of, config, operate } from 'rxjs';
 import * as sinon from 'sinon';
 import { asInteropSubscriber } from './helpers/interop-helper';
@@ -301,35 +301,40 @@ describe('Subscriber', () => {
     });
   });
 
-  const FinalizationRegistry = (global as any).FinalizationRegistry;
-  if (FinalizationRegistry && global.gc) {
-    it('should not leak the destination', (done) => {
-      let observer: Observer<number> | undefined = {
-        next() {
-          /* noop */
-        },
-        error() {
-          /* noop */
-        },
-        complete() {
-          /* noop */
-        },
-      };
+  it('should not leak the destination', function (done) {
+    this.timeout(10000);
 
-      const registry = new FinalizationRegistry((value: any) => {
-        expect(value).to.equal('observer');
-        done();
-      });
-      registry.register(observer, 'observer');
+    const observer: Observer<number> | undefined = {
+      next() {
+        /* noop */
+      },
+      error() {
+        /* noop */
+      },
+      complete() {
+        /* noop */
+      },
+    };
+
+    /**
+     * Use WeakRef instead of FinalizationRegistry (as was originally used). Per MDN, FinalizationRegistry is not a deterministic enough mechanism
+     * on which to base reliable tests: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/FinalizationRegistry
+     */
+    const weakRef = new WeakRef(observer);
 
-      const subscription = of(42).subscribe(observer);
+    // Subscribe to the observable which will complete and unsubscribe automatically. This should not cause any remaining references to the observer after garbage collection.
+    of(42).subscribe(observer);
 
-      observer = undefined;
+    setTimeout(() => {
       global.gc?.();
-    });
-  } else {
-    console.warn(`No support for FinalizationRegistry in Node ${process.version}`);
-  }
+
+      if (weakRef.deref() === undefined) {
+        done();
+      } else {
+        done(new Error('Observer was not garbage collected - possible memory leak'));
+      }
+    }, 1000);
+  });
 });
 
 describe('operate', () => {

packages/rxjs/tsconfig.json

@@ -9,7 +9,7 @@
     "moduleResolution": "node",
     "stripInternal": true,
     "noEmit": true,
-    "lib": ["esnext", "dom"],
+    "lib": ["es2022", "dom"],
     "target": "esnext",
     "baseUrl": ".",
     "paths": {