Fix createRequire so it works for local node_modules.

For most uses of `require()` in emscripten this does not matter since
we load mostly system libraries.  However for the `ws` module it is
needed.  This bug was being masked by the fact that we were setting
`NODE_PATH` in our socket test running.  This is no longer needed now
that we run (non-parallel) tests in the emscripten tree (in out/test).

This is followup to emscripten-core#23265 which itself was an attempt to revert 23169.

Fixes: emscripten-core#23503

src/shell.js

@@ -105,7 +105,7 @@ if (ENVIRONMENT_IS_NODE) {
   // We need to use `createRequire()` to construct the require()` function.
   const { createRequire } = await import('module');
   /** @suppress{duplicate} */
-  var require = createRequire('/');
+  var require = createRequire(import.meta.url);
 #endif
 
 #if PTHREADS || WASM_WORKERS

test/common.py

@@ -1334,7 +1334,7 @@ def verify_es5(self, filename):
       self.fail('es-check failed to verify ES5 output compliance')
 
   # Build JavaScript code from source code
-  def build(self, filename, libraries=None, includes=None, force_c=False, output_suffix='.js', emcc_args=None, output_basename=None):
+  def build(self, filename, libraries=None, includes=None, force_c=False, emcc_args=None, output_basename=None, output_suffix=None):
     if not os.path.exists(filename):
       filename = test_file(filename)
     compiler = [compiler_for(filename, force_c)]
@@ -1343,6 +1343,9 @@ def build(self, filename, libraries=None, includes=None, force_c=False, output_s
       assert shared.suffix(filename) != '.c', 'force_c is not needed for source files ending in .c'
       compiler.append('-xc')
 
+    if not output_suffix:
+      output_suffix = '.mjs' if emcc_args and '-sEXPORT_ES6' in emcc_args else '.js'
+
     if output_basename:
       output = output_basename + output_suffix
     else:

test/other/codesize/test_codesize_minimal_esm.gzsize

@@ -1 +1 @@
-1539
+1540

test/other/codesize/test_codesize_minimal_esm.jssize

@@ -1 +1 @@
-3209
+3221

test/test_sockets.py

@@ -117,10 +117,11 @@ def __enter__(self):
       npm_checked = True
 
     # compile the server
-    proc = run_process([EMCC, '-Werror', test_file(self.filename), '-o', 'server.js', '-DSOCKK=%d' % self.listen_port] + self.args)
+    suffix = '.mjs' if '-sEXPORT_ES6' in self.args else '.js'
+    proc = run_process([EMCC, '-Werror', test_file(self.filename), '-o', 'server' + suffix, '-DSOCKK=%d' % self.listen_port] + self.args)
     print('Socket server build: out:', proc.stdout or '', '/ err:', proc.stderr or '')
 
-    process = Popen(config.NODE_JS + ['server.js'])
+    process = Popen(config.NODE_JS + ['server' + suffix])
     self.processes.append(process)
     return self
 
@@ -166,11 +167,6 @@ def setUpClass(cls):
     print('Running the socket tests. Make sure the browser allows popups from localhost.')
     print()
 
-    # Use emscripten root for node module lookup.  This is needed because the unit tests each
-    # run with CWD set to a temporary directory outside the emscripten tree.
-    print('Setting NODE_PATH=' + path_from_root('node_modules'))
-    os.environ['NODE_PATH'] = path_from_root('node_modules')
-
   # Note: in the WebsockifyServerHarness and CompiledServerHarness tests below, explicitly use
   # consecutive server listen ports, because server teardown might not occur deterministically
   # (python dtor time) and is a bit racy.
@@ -283,7 +279,7 @@ def test_enet(self):
   @crossplatform
   @parameterized({
     'native': [WebsockifyServerHarness, 59160, ['-DTEST_DGRAM=0']],
-    'tcp': [CompiledServerHarness, 59162, ['-DTEST_DGRAM=0']],
+    'tcp': [CompiledServerHarness, 59162, ['-DTEST_DGRAM=0', '-sEXPORT_ES6', '--extern-post-js', test_file('modularize_post_js.js')]],
     'udp': [CompiledServerHarness, 59164, ['-DTEST_DGRAM=1']],
     'pthread': [CompiledServerHarness, 59166, ['-pthread', '-sPROXY_TO_PTHREAD']],
   })