feat: support SASS-PATH env variable

src/getSassOptions.js

@@ -106,9 +106,14 @@ function getSassOptions(loaderContext, loaderOptions, content, implementation) {
     ? proxyCustomImporters(options.importer, resourcePath)
     : [];
 
-  options.includePaths = (options.includePaths || []).concat(
-    path.dirname(resourcePath)
-  );
+  options.includePaths = []
+    .concat(options.includePaths || [])
+    .concat(
+      process.env.SASS_PATH
+        ? process.env.SASS_PATH.split(process.platform === 'win32' ? ';' : ':')
+        : []
+    )
+    .concat(path.dirname(resourcePath));
 
   return options;
 }

test/__snapshots__/loader.test.js.snap

@@ -224,6 +224,60 @@ SassError: expected \\"{\\".",
 
 exports[`loader should output an understandable error with a problem in "@use" (dart-sass) (scss): warnings 1`] = `Array []`;
 
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (sass): css 1`] = `
+".foo {
+  color: red;
+}
+
+.bar {
+  color: blue;
+}"
+`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (sass): errors 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (sass): warnings 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (scss): css 1`] = `
+".foo {
+  color: red;
+}
+
+.bar {
+  color: blue;
+}"
+`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (scss): errors 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (dart-sass) (scss): warnings 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (sass): css 1`] = `
+".foo {
+  color: red; }
+
+.bar {
+  color: blue; }
+"
+`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (sass): errors 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (sass): warnings 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (scss): css 1`] = `
+".foo {
+  color: red; }
+
+.bar {
+  color: blue; }
+"
+`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (scss): errors 1`] = `Array []`;
+
+exports[`loader should respect the "SASS_PATH" environment variable (node-sass) (scss): warnings 1`] = `Array []`;
+
 exports[`loader should throw an error with a explicit file and a file does not exist (dart-sass) (sass): errors 1`] = `
 Array [
   "ModuleBuildError: Module build failed (from ../src/cjs.js):

test/loader.test.js

@@ -655,6 +655,39 @@ describe('loader', () => {
         expect(getErrors(stats)).toMatchSnapshot('errors');
       });
 
+      it(`should respect the "SASS_PATH" environment variable (${implementationName}) (${syntax})`, async () => {
+        const OLD_SASS_PATH = process.env.SASS_PATH;
+
+        process.env.SASS_PATH =
+          process.platform === 'win32'
+            ? `${path.resolve('test', syntax, 'sass_path')};${path.resolve(
+                'test',
+                syntax,
+                'sass_path_other'
+              )}`
+            : `${path.resolve('test', syntax, 'sass_path')}:${path.resolve(
+                'test',
+                syntax,
+                'sass_path_other'
+              )}`;
+
+        const testId = getTestId('sass_path-env', syntax);
+        const options = {
+          implementation: getImplementationByName(implementationName),
+        };
+        const compiler = getCompiler(testId, { loader: { options } });
+        const stats = await compile(compiler);
+        const codeFromBundle = getCodeFromBundle(stats, compiler);
+        const codeFromSass = getCodeFromSass(testId, options);
+
+        expect(codeFromBundle.css).toBe(codeFromSass.css);
+        expect(codeFromBundle.css).toMatchSnapshot('css');
+        expect(getWarnings(stats)).toMatchSnapshot('warnings');
+        expect(getErrors(stats)).toMatchSnapshot('errors');
+
+        process.env.SASS_PATH = OLD_SASS_PATH;
+      });
+
       if (implementation === dartSass) {
         it(`should output an understandable error with a problem in "@use" (${implementationName}) (${syntax})`, async () => {
           const testId = getTestId('error-use', syntax);

test/sass/sass_path-env.sass

@@ -0,0 +1,2 @@
+@import 'file'
+@import 'other'

test/sass/sass_path/file.sass

@@ -0,0 +1,2 @@
+.foo
+  color: red

test/sass/sass_path_other/other.sass

@@ -0,0 +1,2 @@
+.bar
+  color: blue

test/scss/sass_path-env.scss

@@ -0,0 +1,2 @@
+@import 'file';
+@import 'other';

test/scss/sass_path/file.scss

@@ -0,0 +1,3 @@
+.foo {
+  color: red;
+}

test/scss/sass_path_other/other.scss

@@ -0,0 +1,3 @@
+.bar {
+  color: blue;
+}