De-duplicate hoisted imports and avoid rewriting imports of built-ins (#142)

* De-duplicate hoisted imports and avoid rewriting imports of built-ins
* Add changelog entry and bump version number

Author: amannn

CHANGELOG.md

@@ -1,5 +1,6 @@
 # Change Log
-## [Unreleased]
+## [2.2.2] - Unreleased
+* De-duplicate hoisted imports and avoid rewriting imports of built-ins. [#142](https://github.com/shakacode/sass-resources-loader/pull/142) by [Jan Amann](https://github.com/amannn).
 
 ## [2.2.1] - 2021-04-14
 * Support multi-line imports with @use syntax. Fixes: [#135](https://github.com/shakacode/sass-resources-loader/issues/135). [#140](https://github.com/shakacode/sass-resources-loader/pull/140) by [Toms Burgmanis](https://github.com/tomburgs).

package.json

@@ -1,6 +1,6 @@
 {
   "name": "sass-resources-loader",
-  "version": "2.2.1",
+  "version": "2.2.2",
   "description": "SASS resources loader for Webpack",
   "main": "lib/loader.js",
   "files": [

src/utils/processResources.js

@@ -9,12 +9,23 @@ const useRegexTest = new RegExp(useRegex, 'm');
 // Makes sure that only the last instance of `useRegex` variable is found
 const useRegexReplace = new RegExp(`${useRegex}(?![\\s\\S]*${useRegex})`, 'gm');
 
-const getOutput = (source, resources, { hoistUseStatements }) => {
+export const getOutput = (source, resources, { hoistUseStatements }) => {
   if (hoistUseStatements && useRegexTest.test(source)) {
-    return source.replace(
+    const output = source.replace(
       useRegexReplace,
-      useStatements => `${useStatements}\n${resources}`,
+      (useStatements) => `${useStatements}\n${resources}`,
     );
+
+    // De-duplicate identical imports
+    const importedResources = {};
+    return output.replace(new RegExp(useRegex, 'mg'), (importedResource) => {
+      if (importedResources[importedResource]) {
+        return '';
+      }
+
+      importedResources[importedResource] = true;
+      return importedResource;
+    });
   }
 
   return `${resources}\n${source}`;

src/utils/rewritePaths.js

@@ -22,8 +22,12 @@ export default function rewritePaths(error, file, contents, moduleContext, callb
     return callback(null, contents);
   }
 
-
   const rewritten = contents.replace(useRegexp, (entire, importer, single, double, unquoted) => {
+    // Don't rewrite imports from built-ins
+    if (single.indexOf('sass:') === 0) {
+      return entire;
+    }
+
     const oldUsePath = single || double || unquoted;
 
     const absoluteUsePath = path.join(path.dirname(file), oldUsePath);

test/__snapshots__/index.test.js.snap

@@ -98,6 +98,20 @@ div {
 "
 `;
 
+exports[`sass-resources-loader imports should not rewrite the path for built-ins with @use 1`] = `
+"// Should be de-duplicated
+@use 'sass:math';
+
+
+$padding: #{math.div(4 / 2)}px;
+
+div {
+    padding: $padding;
+    margin: #{math.div(4 / 2)}px;;
+}
+"
+`;
+
 exports[`sass-resources-loader imports should preserve import method 1`] = `
 "@use 'shared/index' as secret;
 @import 'shared/variables';
@@ -126,6 +140,10 @@ exports[`sass-resources-loader resources should parse array resources 1`] = `
 
 @forward \\"variables\\";
 
+@use 'sass:math';
+
+$padding: #{math.div(4 / 2)}px;
+
 $text-color: $ccc;
 
 @mixin my-mixin {

test/index.test.js

@@ -1,6 +1,7 @@
 const path = require('path');
 const webpack = require('webpack');
 const { merge } = require('webpack-merge');
+const { getOutput } = require('../src/utils/processResources');
 
 const pathToLoader = require.resolve('../lib/loader.js');
 
@@ -240,5 +241,29 @@ describe('sass-resources-loader', () => {
       const output = require('./output/imports2').default;
       expect(output).toMatchSnapshot();
     }));
+
+    it('should not rewrite the path for built-ins with @use', () => execTest('use-builtin', {
+      hoistUseStatements: true,
+      resources: [
+        path.resolve(__dirname, './scss/shared/_math.scss'),
+      ],
+    }).then(() => {
+      // eslint-disable-next-line global-require
+      const output = require('./output/use-builtin').default;
+      expect(output).toMatchSnapshot();
+    }));
+  });
+
+  describe('getOutput', () => {
+    it('de-duplicates imports from the source when they\'re present in a resource and `hoiseUseStatements` is enabled', () => {
+      const result = getOutput(
+        "@use 'sass:math';\n@use 'sass:list';\n@use 'sass:map';\ndiv { padding: $padding; }",
+        "@use 'sass:math';\n$padding: 10px;",
+        { hoistUseStatements: true },
+      );
+      expect(result).toBe(
+        "@use 'sass:math';\n@use 'sass:list';\n@use 'sass:map';\n\n$padding: 10px;\ndiv { padding: $padding; }",
+      );
+    });
   });
 });

test/scss/shared/_math.scss

@@ -0,0 +1,3 @@
+@use 'sass:math';
+
+$padding: #{math.div(4 / 2)}px;

test/scss/use-builtin.scss

@@ -0,0 +1,7 @@
+// Should be de-duplicated
+@use 'sass:math';
+
+div {
+    padding: $padding;
+    margin: #{math.div(4 / 2)}px;;
+}