fix: configureFonts should be deterministic (callstack#4095)

Brion-bitzen · Oct 12, 2023 · 557ba69 · 557ba69
1 parent 2bb6256
commit 557ba69
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diff --git a/src/styles/__tests__/fonts.test.js b/src/styles/__tests__/fonts.test.js
@@ -271,4 +271,20 @@ describe('configureFonts', () => {
       },
     });
   });
+
+  it('should be deterministic', () => {
+    // first call that should not mutate the original config
+    configureFonts({
+      config: {
+        labelMedium: {
+          color: 'coral',
+        },
+      },
+    });
+
+    // second call that should return the original config without modification
+    const fontsB = configureFonts({ config: {} });
+
+    expect(fontsB.labelMedium.color).toBeUndefined();
+  });
 });
diff --git a/src/styles/fonts.tsx b/src/styles/fonts.tsx
@@ -99,6 +99,7 @@ function configureV3Fonts(
   }
 
   return Object.assign(
+    {},
     typescale,
     ...Object.entries(config).map(([variantName, variantProperties]) => ({
       [variantName]: {