fix: guaranteed order of preprocessor execution (#1489)

* fix: guaranteed order of preprocessor execution

* test: add regression test for guaranteed order of preprocessor execution

* chore: add changeset

---------

Co-authored-by: Dario Soller <[email protected]>

Author: DarioSoller

.changeset/swift-buses-march.md

@@ -0,0 +1,5 @@
+---
+'style-dictionary': patch
+---
+
+If several preprocessors are defined in the SD configuration, the execution of the preprocessors is now guaranteed in the exact order in which they were configured in the SD configuration.

__tests__/utils/preprocess.test.js

@@ -64,5 +64,34 @@ describe('utils', () => {
         value: '5px',
       });
     });
+
+    it('should support asynchronous preprocessors in the order of the config array', async () => {
+      const output = await preprocess(
+        {
+          foo: {
+            value: '5px',
+          },
+        },
+        ['preprocessorA', 'preprocessorC', 'preprocessorB'],
+        {
+          preprocessorB: (tokens) => {
+            tokens.baz = tokens.qux;
+            return tokens;
+          },
+          preprocessorC: async (tokens) => {
+            await new Promise((resolve) => setTimeout(resolve, 100));
+            tokens.qux = tokens.bar;
+            return tokens;
+          },
+          preprocessorA: (tokens) => {
+            tokens.bar = tokens.foo;
+            return tokens;
+          },
+        },
+      );
+      expect(output).to.have.property('baz').eql({
+        value: '5px',
+      });
+    });
   });
 });

lib/utils/preprocess.js

@@ -38,8 +38,9 @@ export async function preprocess(
 
   const preprocessors = Object.entries(preprocessorObj);
   if (preprocessors.length > 0) {
-    for (const [key, preprocessor] of preprocessors) {
-      if (appliedPreprocessors.includes(key)) {
+    for (const key of appliedPreprocessors) {
+      const preprocessor = preprocessorObj[key];
+      if (preprocessor) {
         processedTokens = await preprocessor(processedTokens, options);
       }
     }