Merge pull request #5909 from NomicFoundation/fix-zod-union-schema

Fix the unionType zod helper

v-next/hardhat-zod-utils/src/index.ts

@@ -32,11 +32,19 @@ export const unionType = (
   types: Parameters<typeof z.union>[0],
   errorMessage: string,
 ) =>
-  // eslint-disable-next-line no-restricted-syntax -- This is the only place we allow z.union
-  z.union(types, {
-    errorMap: () => ({
+  // NOTE: The reason we use `z.any().superRefine` instead of `z.union` is that
+  // we found a bug with the `z.union` method that causes it to return a
+  // "deeper" validation error, when we expecte the `errorMessage`.
+  // See: https://github.com/colinhacks/zod/issues/2940#issuecomment-2380836931
+  z.any().superRefine((val, ctx) => {
+    if (types.some((t) => t.safeParse(val).success)) {
+      return;
+    }
+
+    ctx.addIssue({
+      code: z.ZodIssueCode.custom,
       message: errorMessage,
-    }),
+    });
   });
 
 /**

v-next/hardhat-zod-utils/test/index.ts

@@ -41,6 +41,40 @@ describe("unionType", () => {
 
     assertParseResult(union.safeParse(undefined), "Expected error message");
   });
+
+  it("Should work with deep errors", () => {
+    const mySchema = unionType(
+      [z.string(), z.number()],
+      "Expected a string or number",
+    );
+
+    assertParseResult(mySchema.safeParse(false), "Expected a string or number");
+
+    const mySchema2 = unionType(
+      [z.string().url(), z.number()],
+      "Expected a URL or number",
+    );
+
+    assertParseResult(mySchema2.safeParse(false), "Expected a URL or number");
+    assertParseResult(mySchema2.safeParse("a"), "Expected a URL or number");
+  });
+
+  it("Should accept valid data", () => {
+    const mySchema = unionType(
+      [z.string(), z.number()],
+      "Expected a string or number",
+    );
+
+    mySchema.parse("asd");
+    mySchema.parse(123);
+
+    const mySchema2 = unionType(
+      [z.string().url(), z.number()],
+      "Expected a URL or number",
+    );
+    mySchema2.parse("http://example.com");
+    mySchema2.parse(123);
+  });
 });
 
 describe("conditionalUnionType", () => {