test: support import index file from package

test/index.test.js

@@ -171,6 +171,11 @@ implementations.forEach((implementation) => {
             ));
           it('should resolve sass field correctly', () =>
             execTest(`import-sass-field`));
+          // Works only in dart-sass implementation
+          if (implementation === dartSass) {
+            it('should resolve index file in module correctly', () =>
+              execTest('import-index'));
+          }
         });
         describe('custom importers', () => {
           it('should use custom importer', () =>

test/sass/import-index.sass

@@ -0,0 +1 @@
+@import "~sass-package-with-index"

test/scss/import-index.scss

@@ -0,0 +1 @@
+@import "~scss-package-with-index";

test/tools/createSpec.js

@@ -113,6 +113,13 @@ function createSpec(ext) {
           return;
         }
 
+        if (fileWithoutExt === 'import-index' && implementation !== dartSass) {
+          // Skip CSS imports for all implementations that are not node-sass
+          // CSS imports is a legacy feature that we only support for node-sass
+          // See discussion https://github.com/webpack-contrib/sass-loader/pull/573/files?#r199109203
+          return;
+        }
+
         sassOptions.functions = customFunctions(implementation);
 
         const [name] = implementation.info.split('\t');