Add node_modules to rendererOptions.sass and extend (mrmckeb#60)

Author: dagda1

src/helpers/__tests__/__snapshots__/getDtsSnapshot.test.ts.snap

@@ -1,5 +1,12 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`utils / cssSnapshots includePaths in sass options should find external file from includePaths 1`] = `
+Object {
+  "big-font": "include-path-module__big-font---Td7hY",
+  "class-with-mixin": "include-path-module__class-with-mixin---1u87_",
+}
+`;
+
 exports[`utils / cssSnapshots with a custom renderer should process a file and log 1`] = `
 Object {
   "exampleFileContents": "exampleFileContents__exampleFileContents---e3Nf2",

src/helpers/__tests__/external/package/_external.module.scss

@@ -0,0 +1,9 @@
+@import 'mixin';
+
+.class-with-mixin {
+  @include set-margin(0);
+}
+
+.big-font {
+  font-size: 82px;
+}

src/helpers/__tests__/fixtures/include-path.module.scss

@@ -0,0 +1 @@
+@import 'package/external.module.scss';

src/helpers/__tests__/getDtsSnapshot.test.ts

@@ -80,4 +80,29 @@ describe('utils / cssSnapshots', () => {
       expect(mockLogger.log).toHaveBeenCalledWith('Example log');
     });
   });
+
+  describe('includePaths in sass options', () => {
+    const fullFileName = join(
+      __dirname,
+      'fixtures',
+      'include-path.module.scss',
+    );
+    const testFile = readFileSync(fullFileName, 'utf8');
+
+    it('should find external file from includePaths', () => {
+      const classes = getClasses(
+        processor,
+        testFile,
+        fullFileName,
+        {
+          rendererOptions: {
+            sass: { includePaths: [join(__dirname, 'external')] },
+          },
+        },
+        mockLogger,
+      );
+
+      expect(classes).toMatchSnapshot();
+    });
+  });
 });

src/helpers/getClasses.ts

@@ -52,12 +52,13 @@ export const getClasses = (
       );
     } else if (fileType === FileTypes.scss) {
       const filePath = getFilePath(fileName);
+      const { includePaths, ...sassOptions } = rendererOptions.sass || {};
 
       transformedCss = sass
         .renderSync({
           data: css,
-          includePaths: [filePath],
-          ...(rendererOptions.sass || {}),
+          includePaths: [filePath, 'node_modules', ...(includePaths || [])],
+          ...sassOptions,
         })
         .css.toString();
     } else {