Merge pull request #3673 from atingmicrosoft/atingmicrosoft/fix-scss-…

…issues

[heft-sass-plugin] Fix identification of SASS partials on Windows

common/changes/@rushstack/heft-sass-plugin/atingmicrosoft-fix-scss-issues_2022-10-05-00-02.json

@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-sass-plugin",
+      "comment": "Fix an issue with identifying partial sass files on Windows.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/heft-sass-plugin"
+}

heft-plugins/heft-sass-plugin/src/SassProcessor.ts

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
 // See LICENSE in the project root for license information.
 
+import * as path from 'path';
 import { render, Result, SassError } from 'node-sass';
 import * as postcss from 'postcss';
 import cssModules from 'postcss-modules';
@@ -168,8 +169,7 @@ export class SassProcessor extends StringValuesTypingsGenerator {
    * Partial filenames always begin with a leading underscore and do not produce a CSS output file.
    */
   private _isSassPartial(filePath: string): boolean {
-    const lastSlashIndex: number = filePath.lastIndexOf('/');
-    return filePath.charAt(lastSlashIndex + 1) === '_';
+    return path.basename(filePath)[0] === '_';
   }
 
   private async _transpileSassAsync(