Follow up: unify v3 and v4 zod types via describe matrix and a test helper (#1141)

src/shared/zodTestMatrix.ts

@@ -0,0 +1,22 @@
+import * as z3 from 'zod/v3';
+import * as z4 from 'zod/v4';
+
+// Shared Zod namespace type that exposes the common surface area used in tests.
+export type ZNamespace = typeof z3 & typeof z4;
+
+export const zodTestMatrix = [
+    {
+        zodVersionLabel: 'Zod v3',
+        z: z3 as ZNamespace,
+        isV3: true as const,
+        isV4: false as const
+    },
+    {
+        zodVersionLabel: 'Zod v4',
+        z: z4 as ZNamespace,
+        isV3: false as const,
+        isV4: true as const
+    }
+] as const;
+
+export type ZodMatrixEntry = (typeof zodTestMatrix)[number];