esm: minimal resolver spec and implementation refinementsmodules-lkgr

PR URL: https://github.com/nodejs/ecmascript-modules/pull/12

2 files changed, 16 insertions, 27 deletions

diff --git a/lib/internal/errors.js b/lib/internal/errors.js
index 0ed23a9438..9c7aa71bd4 100644
--- a/lib/internal/errors.js
+++ b/lib/internal/errors.js
@@ -800,11 +800,13 @@ E('ERR_MISSING_ARGS',
 E('ERR_MISSING_DYNAMIC_INSTANTIATE_HOOK',
   'The ES Module loader may not return a format of \'dynamic\' when no ' +
   'dynamicInstantiate function was provided', Error);
-E('ERR_MISSING_MODULE', 'Cannot find module %s', Error);
-E('ERR_MODULE_RESOLUTION_LEGACY',
-  '%s not found by import in %s.' +
-    ' Legacy behavior in require() would have found it at %s',
-  Error);
+E('ERR_MODULE_NOT_FOUND', (module, base, legacyResolution) => {
+  let msg = `Cannot find module '${module}' imported from ${base}.`;
+  if (legacyResolution)
+    msg += ' Legacy behavior in require() would have found it at ' +
+           legacyResolution;
+  return msg;
+}, Error);
 E('ERR_MULTIPLE_CALLBACK', 'Callback called multiple times', Error);
 E('ERR_NAPI_CONS_FUNCTION', 'Constructor must be a function', TypeError);
 E('ERR_NAPI_INVALID_DATAVIEW_ARGS',
@@ -898,11 +900,13 @@ E('ERR_UNHANDLED_ERROR',
     if (err === undefined) return msg;
     return `${msg} (${err})`;
   }, Error);
+// This should probably be a `TypeError`.
 E('ERR_UNKNOWN_CREDENTIAL', '%s identifier does not exist: %s', Error);
 E('ERR_UNKNOWN_ENCODING', 'Unknown encoding: %s', TypeError);
 
 // This should probably be a `TypeError`.
-E('ERR_UNKNOWN_FILE_EXTENSION', 'Unknown file extension: %s', Error);
+E('ERR_UNKNOWN_FILE_EXTENSION', 'Unknown file extension: \'%s\' imported ' +
+  'from %s', Error);
 E('ERR_UNKNOWN_MODULE_FORMAT', 'Unknown module format: %s', RangeError);
 E('ERR_UNKNOWN_SIGNAL', 'Unknown signal: %s', TypeError);
 E('ERR_UNKNOWN_STDIN_TYPE', 'Unknown stdin file type', Error);
diff --git a/lib/internal/modules/esm/default_resolve.js b/lib/internal/modules/esm/default_resolve.js
index 5976cab99c..4d47d8124e 100644
--- a/lib/internal/modules/esm/default_resolve.js
+++ b/lib/internal/modules/esm/default_resolve.js
@@ -10,21 +10,15 @@ const { getOptionValue } = require('internal/options');
 const preserveSymlinks = getOptionValue('--preserve-symlinks');
 const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
 const {
-  ERR_MISSING_MODULE,
-  ERR_MODULE_RESOLUTION_LEGACY,
+  ERR_MODULE_NOT_FOUND,
   ERR_UNKNOWN_FILE_EXTENSION
 } = require('internal/errors').codes;
 const { resolve: moduleWrapResolve } = internalBinding('module_wrap');
-const StringStartsWith = Function.call.bind(String.prototype.startsWith);
 const { pathToFileURL, fileURLToPath } = require('internal/url');
 
 const realpathCache = new Map();
 
 function search(target, base) {
-  if (base === undefined) {
-    // We cannot search without a base.
-    throw new ERR_MISSING_MODULE(target);
-  }
   try {
     return moduleWrapResolve(target, base);
   } catch (e) {
@@ -36,7 +30,7 @@ function search(target, base) {
       tmpMod.paths = CJSmodule._nodeModulePaths(
         new URL('./', questionedBase).pathname);
       const found = CJSmodule._resolveFilename(target, tmpMod);
-      error = new ERR_MODULE_RESOLUTION_LEGACY(target, base, found);
+      error = new ERR_MODULE_NOT_FOUND(target, fileURLToPath(base), found);
     } catch {
       // ignore
     }
@@ -57,16 +51,8 @@ function resolve(specifier, parentURL) {
     };
   }
 
-  let url;
-  try {
-    url = search(specifier,
-                 parentURL || pathToFileURL(`${process.cwd()}/`).href);
-  } catch (e) {
-    if (typeof e.message === 'string' &&
-        StringStartsWith(e.message, 'Cannot find module'))
-      e.code = 'MODULE_NOT_FOUND';
-    throw e;
-  }
+  let url = search(specifier,
+                   parentURL || pathToFileURL(`${process.cwd()}/`).href);
 
   const isMain = parentURL === undefined;
 
@@ -87,12 +73,11 @@ function resolve(specifier, parentURL) {
     if (isMain)
       format = 'cjs';
     else
-      throw new ERR_UNKNOWN_FILE_EXTENSION(url.pathname);
+      throw new ERR_UNKNOWN_FILE_EXTENSION(url.pathname,
+                                           fileURLToPath(parentURL));
   }
 
   return { url: `${url}`, format };
 }
 
 module.exports = resolve;
-// exported for tests
-module.exports.search = search;