worker: improve code coverage

lib/internal/worker.js

@@ -496,6 +496,7 @@ function eventLoopUtilization(util1, util2) {
 }
 
 module.exports = {
+  kHandle,
   ownsProcessState,
   isMainThread,
   SHARE_ENV,

test/parallel/test-worker-environmentdata.js

@@ -1,4 +1,5 @@
 'use strict';
+// Flags: --expose-internals
 
 require('../common');
 const {
@@ -8,6 +9,8 @@ const {
   threadId,
 } = require('worker_threads');
 
+const { assignEnvironmentData } = require('internal/worker');
+
 const {
   deepStrictEqual,
   strictEqual,
@@ -26,6 +29,8 @@ if (!process.env.HAS_STARTED_WORKER) {
   strictEqual(getEnvironmentData('foo'), 'bar');
   deepStrictEqual(getEnvironmentData('hello'), { value: 'world' });
   strictEqual(getEnvironmentData(1), undefined);
+  assignEnvironmentData(undefined); // It won't setup any key.
+  strictEqual(getEnvironmentData(undefined), undefined);
 
   // Recurse to make sure the environment data is inherited
   if (threadId <= 2)

test/parallel/test-worker-heap-snapshot.js

@@ -0,0 +1,22 @@
+'use strict';
+
+// Flags: --expose-internals
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker_threads');
+const { HeapSnapshotStream } = require('internal/heap_utils');
+const { kHandle } = require('internal/worker');
+
+const worker = new Worker(__filename);
+const snapShotResult = { ondone: () => {} };
+worker[kHandle].takeHeapSnapshot = common.mustCall(() => snapShotResult);
+
+worker.on('online', () => {
+  const snapShotResponse = worker.getHeapSnapshot();
+  snapShotResult.ondone({});
+
+  snapShotResponse.then(common.mustCall((heapSnapshotStream) => {
+    assert.ok(heapSnapshotStream instanceof HeapSnapshotStream);
+    worker.terminate();
+  }));
+});