lib: improve error message on missing module

doc/api/errors.md

@@ -1964,7 +1964,12 @@ an `Error` with this code will be emitted.
 
 <a id="MODULE_NOT_FOUND"></a>
 ### MODULE_NOT_FOUND
-
+<!-- YAML
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/25690
+    description: Added `requireStack` property.
+-->
 A module file could not be resolved while attempting a [`require()`][] or
 `import` operation.
 

lib/internal/modules/cjs/loader.js

@@ -606,9 +606,20 @@ Module._resolveFilename = function(request, parent, isMain, options) {
   // Look up the filename first, since that's the cache key.
   var filename = Module._findPath(request, paths, isMain);
   if (!filename) {
+    const requireStack = [];
+    for (var cursor = parent;
+      cursor;
+      cursor = cursor.parent) {
+      requireStack.push(cursor.filename || cursor.id);
+    }
+    let message = `Cannot find module '${request}'`;
+    if (requireStack.length > 0) {
+      message = message + '\nRequire stack:\n- ' + requireStack.join('\n- ');
+    }
     // eslint-disable-next-line no-restricted-syntax
-    var err = new Error(`Cannot find module '${request}'`);
+    var err = new Error(message);
     err.code = 'MODULE_NOT_FOUND';
+    err.requireStack = requireStack;
     throw err;
   }
   return filename;

lib/internal/modules/esm/default_resolve.js

@@ -66,8 +66,11 @@ function resolve(specifier, parentURL) {
                  parentURL || pathToFileURL(`${process.cwd()}/`).href);
   } catch (e) {
     if (typeof e.message === 'string' &&
-        StringStartsWith(e.message, 'Cannot find module'))
+        StringStartsWith(e.message, 'Cannot find module')) {
       e.code = 'MODULE_NOT_FOUND';
+      // TODO: also add e.requireStack to match behavior with CJS
+      // MODULE_NOT_FOUND.
+    }
     throw e;
   }
 

test/fixtures/require-resolve.js

@@ -15,21 +15,21 @@ assert.strictEqual(
 // Verify that existing paths are removed.
 assert.throws(() => {
   require.resolve('bar', { paths: [] })
-}, /^Error: Cannot find module 'bar'$/);
+}, /^Error: Cannot find module 'bar'/);
 
 // Verify that resolution path can be overwritten.
 {
   // three.js cannot be loaded from this file by default.
   assert.throws(() => {
     require.resolve('three')
-  }, /^Error: Cannot find module 'three'$/);
+  }, /^Error: Cannot find module 'three'/);
 
   // If the nested-index directory is provided as a resolve path, 'three'
   // cannot be found because nested-index is used as a starting point and not
   // a searched directory.
   assert.throws(() => {
     require.resolve('three', { paths: [nestedIndex] })
-  }, /^Error: Cannot find module 'three'$/);
+  }, /^Error: Cannot find module 'three'/);
 
   // Resolution from nested index directory also checks node_modules.
   assert.strictEqual(

test/parallel/test-internal-modules.js

@@ -5,7 +5,7 @@ const assert = require('assert');
 
 assert.throws(function() {
   require('internal/freelist');
-}, /^Error: Cannot find module 'internal\/freelist'$/);
+}, /^Error: Cannot find module 'internal\/freelist'/);
 
 assert.strictEqual(
   require(fixtures.path('internal-modules')),

test/parallel/test-loaders-hidden-from-users.js

@@ -9,7 +9,7 @@ common.expectsError(
     require('internal/bootstrap/loaders');
   }, {
     code: 'MODULE_NOT_FOUND',
-    message: 'Cannot find module \'internal/bootstrap/loaders\''
+    message: /Cannot find module 'internal\/bootstrap\/loaders'/
   }
 );
 
@@ -20,6 +20,6 @@ common.expectsError(
     require('owo');
   }, {
     code: 'MODULE_NOT_FOUND',
-    message: 'Cannot find module \'owo\''
+    message: /Cannot find module 'owo'/
   }
 );

test/parallel/test-module-loading-error.js

@@ -80,9 +80,10 @@ common.expectsError(
     message: 'The argument \'id\' must be a non-empty string. Received \'\''
   });
 
-common.expectsError(
+assert.throws(
   () => { require('../fixtures/packages/is-dir'); },
   {
     code: 'MODULE_NOT_FOUND',
-    message: 'Cannot find module \'../fixtures/packages/is-dir\''
-  });
+    message: /Cannot find module '\.\.\/fixtures\/packages\/is-dir'/
+  }
+);

test/parallel/test-module-multi-extensions.js

@@ -35,7 +35,7 @@ fs.writeFileSync(dotfileWithExtension, 'console.log(__filename);', 'utf8');
   require(modulePath);
   assert.throws(
     () => require(`${modulePath}.foo`),
-    new Error(`Cannot find module '${modulePath}.foo'`)
+    (err) => err.message.startsWith(`Cannot find module '${modulePath}.foo'`)
   );
   require(`${modulePath}.foo.bar`);
   delete require.cache[file];
@@ -47,7 +47,7 @@ fs.writeFileSync(dotfileWithExtension, 'console.log(__filename);', 'utf8');
   const modulePath = path.join(tmpdir.path, 'test-extensions');
   assert.throws(
     () => require(modulePath),
-    new Error(`Cannot find module '${modulePath}'`)
+    (err) => err.message.startsWith(`Cannot find module '${modulePath}'`)
   );
   delete require.cache[file];
   Module._pathCache = Object.create(null);
@@ -69,7 +69,7 @@ fs.writeFileSync(dotfileWithExtension, 'console.log(__filename);', 'utf8');
   const modulePath = path.join(tmpdir.path, 'test-extensions.foo');
   assert.throws(
     () => require(modulePath),
-    new Error(`Cannot find module '${modulePath}'`)
+    (err) => err.message.startsWith(`Cannot find module '${modulePath}'`)
   );
   delete require.extensions['.foo.bar'];
   Module._pathCache = Object.create(null);

test/parallel/test-repl.js

@@ -534,6 +534,8 @@ const errorTests = [
     expect: [
       'Thrown:',
       /^{ Error: Cannot find module 'internal\/repl'/,
+      /^Require stack:/,
+      /^- <repl>/,
       /^    at .*/,
       /^    at .*/,
       /^    at .*/,

test/sequential/test-module-loading.js

@@ -131,7 +131,7 @@ require('../fixtures/node_modules/foo');
   assert.ok(my_path.path_func instanceof Function);
   // this one does not exist and should throw
   assert.throws(function() { require('./utils'); },
-                /^Error: Cannot find module '\.\/utils'$/);
+                /^Error: Cannot find module '\.\/utils'/);
 }
 
 let errorThrown = false;
@@ -170,12 +170,13 @@ assert.strictEqual(require('../fixtures/registerExt2').custom, 'passed');
 assert.strictEqual(require('../fixtures/foo').foo, 'ok');
 
 // Should not attempt to load a directory
-try {
-  tmpdir.refresh();
-  require(tmpdir.path);
-} catch (err) {
-  assert.strictEqual(err.message, `Cannot find module '${tmpdir.path}'`);
-}
+assert.throws(
+  () => {
+    tmpdir.refresh();
+    require(tmpdir.path);
+  },
+  (err) => err.message.startsWith(`Cannot find module '${tmpdir.path}`)
+);
 
 {
   // Check load order is as expected