test: replace internal API test with public API test

The internal freelist `hasItems()` test use the internal API directly.
This commit changes them to use the API as it is exposed publicly. It
tests the same code paths, but does it without needing
`--expose-internals`.

Refs: nodejs#27588 (review)

test/parallel/test-freelist.js

@@ -28,13 +28,3 @@ assert.strictEqual(flist1.free({ id: 'test5' }), false);
 assert.strictEqual(flist1.alloc().id, 'test3');
 assert.strictEqual(flist1.alloc().id, 'test2');
 assert.strictEqual(flist1.alloc().id, 'test1');
-
-// Check list has elements
-const flist2 = new FreeList('flist2', 2, Object);
-assert.strictEqual(flist2.hasItems(), false);
-
-flist2.free({ id: 'test1' });
-assert.strictEqual(flist2.hasItems(), true);
-
-flist2.alloc();
-assert.strictEqual(flist2.hasItems(), false);

test/parallel/test-http-common.js

@@ -1,9 +1,11 @@
 'use strict';
 require('../common');
 const assert = require('assert');
-const httpCommon = require('_http_common');
-const checkIsHttpToken = httpCommon._checkIsHttpToken;
-const checkInvalidHeaderChar = httpCommon._checkInvalidHeaderChar;
+const {
+  _checkInvalidHeaderChar: checkInvalidHeaderChar,
+  _checkIsHttpToken: checkIsHttpToken,
+  parsers
+} = require('_http_common');
 
 // checkIsHttpToken
 assert(checkIsHttpToken('t'));
@@ -31,3 +33,13 @@ assert.strictEqual(checkInvalidHeaderChar('tt'), false);
 assert.strictEqual(checkInvalidHeaderChar('ttt'), false);
 assert.strictEqual(checkInvalidHeaderChar('tttt'), false);
 assert.strictEqual(checkInvalidHeaderChar('ttttt'), false);
+
+// parsers
+{
+  const dummyParser = { id: 'fhqwhgads' };
+  assert.strictEqual(parsers.hasItems(), false);
+  assert.strictEqual(parsers.free(dummyParser), true);
+  assert.strictEqual(parsers.hasItems(), true);
+  assert.strictEqual(parsers.alloc(), dummyParser);
+  assert.strictEqual(parsers.hasItems(), false);
+}