fix/zod contracts lose branding (#513)

* fix: #511 use type inference from zod in zodContract * fix zodContracts output type inference * fix: Import missing type * Update quick-adults-punch.md * Format --------- Co-authored-by: Igor Kamyşev <[email protected]>
igorkamyshev · Sep 4, 2024 · 7769b64 · 7769b64
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commit 7769b64
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diff --git a/.changeset/quick-adults-punch.md b/.changeset/quick-adults-punch.md
@@ -0,0 +1,5 @@
+---
+"@farfetched/zod": patch
+---
+
+Fix `zodContracts` type inference for branded types
diff --git a/packages/zod/src/__tests__/contract.test-d.ts b/packages/zod/src/__tests__/contract.test-d.ts
@@ -58,4 +58,17 @@ describe('zodContract', () => {
       >();
     }
   });
+
+  test('branded type', () => {
+    const BrandedContainer = zod.object({
+      branded: zod.string().brand<'Branded'>(),
+    });
+    const brandedContract = zodContract(BrandedContainer);
+
+    const smth: unknown = { branded: 'branded' };
+
+    if (brandedContract.isData(smth)) {
+      expectTypeOf(smth).toEqualTypeOf<zod.infer<typeof BrandedContainer>>();
+    }
+  });
 });
diff --git a/packages/zod/src/zod_contract.ts b/packages/zod/src/zod_contract.ts
@@ -1,4 +1,4 @@
-import { type ZodType } from 'zod';
+import { type ZodType, type TypeOf } from 'zod';
 import { type Contract } from '@farfetched/core';
 
 /**
@@ -7,8 +7,10 @@ import { type Contract } from '@farfetched/core';
  *
  * @param {ZodType} data Zod Contract for valid data
  */
-function zodContract<D>(data: ZodType<D>): Contract<unknown, D> {
-  function isData(prepared: unknown): prepared is D {
+function zodContract<T extends ZodType<any, any, any>>(
+  data: T
+): Contract<unknown, TypeOf<T>> {
+  function isData(prepared: unknown): prepared is T {
     return data.safeParse(prepared).success;
   }