assert: create internal/assert micro-module

For use in built-in modules that could benefit from `assert()` without
having to load the entire module (unless an AssertionError actually
occurs): lib/internal/assert.js.

PR-URL: nodejs#25956
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>

lib/internal/assert.js

@@ -0,0 +1,9 @@
+'use strict';
+
+function assert(value, message) {
+  if (!value) {
+    require('assert')(value, message);
+  }
+}
+
+module.exports = assert;

node.gyp

@@ -85,6 +85,7 @@
       'lib/vm.js',
       'lib/worker_threads.js',
       'lib/zlib.js',
+      'lib/internal/assert.js',
       'lib/internal/assert/assertion_error.js',
       'lib/internal/async_hooks.js',
       'lib/internal/buffer.js',

test/parallel/test-internal-assert.js

@@ -0,0 +1,15 @@
+// Flags: --expose-internals
+'use strict';
+
+require('../common');
+
+const assert = require('assert');
+const internalAssert = require('internal/assert');
+
+// Should not throw.
+internalAssert(true);
+internalAssert(true, 'fhqwhgads');
+
+assert.throws(() => { internalAssert(false); }, assert.AssertionError);
+assert.throws(() => { internalAssert(false, 'fhqwhgads'); },
+              { code: 'ERR_ASSERTION', message: 'fhqwhgads' });