fixup! fixup! fixup! loader: return package format from defaultResolv…

…e if known

test/es-module/test-esm-resolve-type.js

@@ -96,6 +96,42 @@ try {
   };
 
   // Create a dummy dual package
+  //
+  /**
+   * this creates following directory structure:
+   *
+   * ./node_modules:
+   *   |-> my-dual-package
+   *       |-> es
+   *           |-> index.js
+   *           |-> package.json [2]
+   *       |-> lib
+   *           |-> index.js
+   *       |->package.json [1]
+   *
+   * [1] - main package.json of the package
+   *     - it contains:
+   *             - type: 'commonjs'
+   *             - main: 'lib/mainfile.js'
+   *             - conditional exports for 'require' (lib/index.js) and
+   *                                       'import' (es/index.js)
+   * [2] - package.json add-on for the import case
+   *     - it only contains:
+   *             - type: 'module'
+   *
+   * in case the package is consumed as an ESM by importing it:
+   *    import * as my-package from 'my-dual-package'
+   * it will cause the resolve method to return:
+   *  {
+   *     url: '<base_path>/node_modules/my-dual-package/es/index.js',
+   *     format: 'module'
+   *  }
+   *
+   *  following testcase ensures that resolve works correctly in this case
+   *  returning the information as specified above. Source for 'url' value
+   *  is [1], source for 'format' value is [2]
+   */
+
   const moduleName = 'my-dual-package';
 
   const nmDir = rel('node_modules');
@@ -114,7 +150,7 @@ try {
 
   const mainPkgJsonContent = {
     type: 'commonjs',
-    main: 'lib/mainfile.js',
+    main: 'lib/index.js',
     exports: {
       '.': {
         'require': './lib/index.js',
@@ -140,6 +176,7 @@ try {
   // test the resolve
   const resolveResult = resolve(`${moduleName}`);
   assert.strictEqual(resolveResult.format, 'module');
+  assert.ok(resolveResult.url.includes('my-dual-package/es/index.js'));
 
   // cleanup
   fs.unlinkSync(esScript);