fix: convertDTCG for already DTCG input (#1445)

.changeset/eight-cats-juggle.md

@@ -0,0 +1,5 @@
+---
+'style-dictionary': patch
+---
+
+Fix convertToDTCG for sets that are already (partially) DTCG.

__tests__/utils/convertToDTCG.test.js

@@ -247,6 +247,41 @@ describe('utils', () => {
       });
     });
 
+    it('should handle input that is DTCG syntax already properly', () => {
+      const result = convertToDTCG({
+        colors: {
+          red: {
+            $value: '#ff0000',
+            $type: 'color',
+            $extensions: {
+              'com.example': {
+                modify: {
+                  value: 0.5, // <- to check that it doesn't incorrectly identify this as a "token"
+                  type: 'transparentize',
+                },
+              },
+            },
+          },
+        },
+      });
+      expect(result).to.eql({
+        $type: 'color',
+        colors: {
+          red: {
+            $value: '#ff0000',
+            $extensions: {
+              'com.example': {
+                modify: {
+                  value: 0.5,
+                  type: 'transparentize',
+                },
+              },
+            },
+          },
+        },
+      });
+    });
+
     it('should work with any number of nestings', () => {
       const result = convertToDTCG({
         colors: {

lib/utils/convertToDTCG.js

@@ -25,20 +25,18 @@ function recurse(slice, opts) {
   let types = new Set();
 
   // this slice within the dictionary is a design token
-  if (Object.hasOwn(slice, 'value')) {
+  // Check for $value in case the input is already DTCG syntax
+  if (Object.hasOwn(slice, 'value') || Object.hasOwn(slice, '$value')) {
     const token = /** @type {DesignToken} */ (slice);
-    // convert to $ prefixed properties
     Object.keys(token).forEach((key) => {
-      switch (key) {
-        case 'type':
-          // track the encountered types for this layer
-          types.add(/** @type {string} */ (token[key]));
-        // eslint-disable-next-line no-fallthrough
-        case 'value':
-        case 'description':
-          token[`$${key}`] = token[key];
-          delete token[key];
-        // no-default
+      if (['type', '$type'].includes(key)) {
+        // track the encountered types for this layer
+        types.add(/** @type {string} */ (token[key]));
+      }
+      // convert to $ prefixed properties
+      if (['type', 'description', 'value'].includes(key)) {
+        token[`$${key}`] = token[key];
+        delete token[key];
       }
     });
     return types;