Hono + Valibot request validation (Vitest): working versions (tested 2026-10-15)

{
  "name": "hono-valibot-validator",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "vitest run --reporter=default --reporter=json --outputFile=test-report.json"
  },
  "dependencies": {
    "hono": "4.13.13",
    "valibot": "1.5.0",
    "@hono/valibot-validator": "0.6.1"
  },
  "devDependencies": {
    "@types/node": "24.19.2",
    "vitest": "5.0.4"
  }
}

import { Hono } from "hono";
import { vValidator } from "@hono/valibot-validator";
import * as v from "valibot";

const Signup = v.object({
  email: v.pipe(v.string(), v.trim(), v.toLowerCase(), v.email()),
  password: v.pipe(v.string(), v.minLength(8)),
  plan: v.optional(v.picklist(["free", "pro"]), "free"),
});
const Paging = v.object({ page: v.optional(v.pipe(v.string(), v.transform(Number), v.integer(), v.minValue(1)), "1") });

export const app = new Hono()
  .post("/signup", vValidator("json", Signup, (result, c) => {
    if (!result.success) return c.json({ error: "invalid", fields: v.flatten(result.issues).nested }, 422);
  }), (c) => c.json(c.req.valid("json"), 201))
  .get("/items", vValidator("query", Paging), (c) => c.json({ page: c.req.valid("query").page }));

import { describe, it, expect } from "vitest";
import { app } from "../src/app";

const post = (body: unknown) => app.request("/signup", { method: "POST", headers: { "content-type": "application/json" }, body: JSON.stringify(body) });

describe("valibot validation", () => {
  it("transforms and defaults", async () => {
    const r = await post({ email: "  ADA@Example.com ", password: "longenough" });
    expect(r.status).toBe(201);
    expect(await r.json()).toEqual({ email: "ada@example.com", password: "longenough", plan: "free" });
  });

  it("custom 422 with field errors", async () => {
    const r = await post({ email: "bad", password: "short", plan: "gold" });
    expect(r.status).toBe(422);
    const body = await r.json();
    expect(Object.keys(body.fields).sort()).toEqual(["email", "password", "plan"]);
  });

  it("query transform", async () => {
    expect(await (await app.request("/items?page=2")).json()).toEqual({ page: 2 });
    expect((await app.request("/items?page=0")).status).toBe(400);
  });
});