backend/spec/requests/error_responses_spec.rb

@@ -2,20 +2,18 @@ require 'rails_helper'
 
 RSpec.describe 'error responses', type: :request do
   describe 'manual input errors' do
-    it 'returns a stable errors array for bad requests' do
-      user = create(:user)
-      sign_in_as(user)
-
-      put "/users/#{ user.id }", params: { name: '   ' }
+    it 'returns a stable payload for bad requests' do
+      get '/tags/name/%20/deerjikists'
 
       expect(response).to have_http_status(:bad_request)
-      expect(json.fetch('errors')).to contain_exactly(
-          include('code' => 'bad_request',
-                  'field' => 'name',
-                  'message' => be_present))
+      expect(json).to include(
+          'type' => 'bad_request',
+          'message' => be_present,
+          'errors' => {},
+          'base_errors' => [be_present])
     end
 
-    it 'returns a stable errors array for unprocessable requests' do
+    it 'returns a stable field-error payload for unprocessable requests' do
       member = create(:user, :member)
       tag = create(:tag, :general, name: 'error_response_tag')
       sign_in_as(member)
@@ -23,25 +21,27 @@ RSpec.describe 'error responses', type: :request do
       patch "/tags/#{ tag.id }", params: { category: 'nico' }
 
       expect(response).to have_http_status(:unprocessable_entity)
-      expect(json.fetch('errors')).to contain_exactly(
-          include('code' => 'invalid',
-                  'field' => 'category',
-                  'message' => be_present))
+      expect(json).to include(
+          'type' => 'validation_error',
+          'message' => '入力内容を確認してください．',
+          'base_errors' => [])
+      expect(json.fetch('errors')).to include(
+          'category' => ['ニコタグは変更できません．'])
     end
   end
 
   describe 'model validation errors' do
-    it 'returns field, code, and message for model errors' do
+    it 'returns field messages for model errors' do
       user = create(:user)
       sign_in_as(user)
 
       put "/users/#{ user.id }", params: { name: 'a' * 256 }
 
       expect(response).to have_http_status(:unprocessable_entity)
-      expect(json.fetch('errors')).to include(
-          include('code' => 'too_long',
-                  'field' => 'name',
-                  'message' => be_present))
+      expect(json).to include(
+          'type' => 'validation_error',
+          'message' => '入力内容を確認してください．')
+      expect(json.fetch('errors').fetch('name')).to include(be_present)
     end
   end
 end

backend/spec/requests/materials_spec.rb

@@ -141,16 +141,21 @@ RSpec.describe 'Materials API', type: :request do
     context 'when logged in' do
       before { sign_in_as(guest_user) }
 
-      it 'returns 400 when tag is blank' do
+      it 'returns 422 when tag is blank' do
         post '/materials', params: { tag: '   ', file: dummy_upload }
 
-        expect(response).to have_http_status(:bad_request)
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+            'tag' => ['タグは必須です．'])
       end
 
-      it 'returns 400 when both file and url are blank' do
+      it 'returns 422 when both file and url are blank' do
         post '/materials', params: { tag: 'material_create_blank' }
 
-        expect(response).to have_http_status(:bad_request)
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+            'file' => ['ファイルまたは URL は必須です．'],
+            'url' => ['ファイルまたは URL は必須です．'])
       end
 
       it 'creates a material with an attached file' do
@@ -261,21 +266,26 @@ RSpec.describe 'Materials API', type: :request do
         expect(response).to have_http_status(:not_found)
       end
 
-      it 'returns 400 when tag is blank' do
+      it 'returns 422 when tag is blank' do
         put "/materials/#{ material.id }", params: {
           tag: '   ',
           file: dummy_upload
         }
 
-        expect(response).to have_http_status(:bad_request)
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+            'tag' => ['タグは必須です．'])
       end
 
-      it 'returns 400 when both file and url are blank' do
+      it 'returns 422 when both file and url are blank' do
         put "/materials/#{ material.id }", params: {
           tag: 'material_update_no_payload'
         }
 
-        expect(response).to have_http_status(:bad_request)
+        expect(response).to have_http_status(:unprocessable_entity)
+        expect(json.fetch('errors')).to include(
+            'file' => ['ファイルまたは URL は必須です．'],
+            'url' => ['ファイルまたは URL は必須です．'])
       end
 
       it 'updates tag, url, file, and updated_by_user' do

backend/spec/requests/nico_tags_spec.rb

@@ -75,7 +75,7 @@ RSpec.describe 'NicoTags', type: :request do
       expect(versions.last.created_by_user_id).to eq(admin.id)
     end
 
-    it '400 when linked tag normalises to nico tag' do
+    it 'returns 422 when linked tag normalises to nico tag' do
       sign_in_as(member)
 
       other_nico = create(:tag, :nico, name: 'nico:linked_ng')
@@ -87,7 +87,9 @@ RSpec.describe 'NicoTags', type: :request do
         patch "/tags/nico/#{nico_tag.id}", params: { tags: 'linked_ng_alias' }
       }.not_to change(NicoTagVersion, :count)
 
-      expect(response).to have_http_status(:bad_request)
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+          'tags' => ['ニコニコ・タグ同士は連携できません．'])
     end
   end
 end

backend/spec/requests/posts_spec.rb

@@ -704,7 +704,7 @@ RSpec.describe 'Posts API', type: :request do
             category: :nico)
       end
 
-      it 'return 400' do
+      it 'returns 422 with tag field errors' do
         sign_in_as(member)
 
         post '/posts', params: post_write_params(
@@ -714,7 +714,13 @@ RSpec.describe 'Posts API', type: :request do
           thumbnail: dummy_upload
         )
 
-        expect(response).to have_http_status(:bad_request), response.body
+        expect(response).to have_http_status(:unprocessable_entity), response.body
+        expect(json).to include(
+            'type' => 'validation_error',
+            'message' => '入力内容を確認してください．',
+            'base_errors' => [])
+        expect(json.fetch('errors')).to include(
+            'tags' => ['ニコニコ・タグは直接指定できません．'])
       end
     end
 
@@ -931,7 +937,7 @@ RSpec.describe 'Posts API', type: :request do
             category: :nico)
       end
 
-      it 'return 400' do
+      it 'returns 422 with tag field errors' do
         sign_in_as(member)
 
         put "/posts/#{post_record.id}", params: post_update_params(
@@ -939,7 +945,13 @@ RSpec.describe 'Posts API', type: :request do
             title: 'updated title',
             tags: 'nico:nico_tag')
 
-        expect(response).to have_http_status(:bad_request), response.body
+        expect(response).to have_http_status(:unprocessable_entity), response.body
+        expect(json).to include(
+            'type' => 'validation_error',
+            'message' => '入力内容を確認してください．',
+            'base_errors' => [])
+        expect(json.fetch('errors')).to include(
+            'tags' => ['ニコニコ・タグは直接指定できません．'])
       end
     end
 

backend/spec/requests/tags_deerjikists_spec.rb

@@ -275,6 +275,30 @@ RSpec.describe 'Tags deerjikists API', type: :request do
         end
       end
 
+      context 'when a row is invalid' do
+        let(:payload) do
+          [
+            { platform: '', code: code1 },
+          ]
+        end
+
+        it 'returns 422 with indexed field errors and does not replace existing deerjikists' do
+          Deerjikist.create!(platform: platform1, code: code1, tag: tag)
+
+          expect {
+            do_request
+          }.not_to change { Deerjikist.where(tag: tag).map { |d| [d.platform, d.code] } }
+
+          expect(response).to have_http_status(:unprocessable_entity)
+          expect(json).to include(
+              'type' => 'validation_error',
+              'message' => '入力内容を確認してください．',
+              'base_errors' => [])
+          expect(json.fetch('errors')).to include(
+              'deerjikists.0.platform' => [be_present])
+        end
+      end
+
       context 'when youtube code is handle' do
         let(:channel_id) { 'UCabcdefghijklmnopqrstuv' }
         let(:payload) do

backend/spec/requests/users_spec.rb

@@ -90,12 +90,14 @@ RSpec.describe 'Users', type: :request do
       expect(response).to have_http_status(:unauthorized)
     end
 
-    it 'returns 400 when name is blank' do
+    it 'returns 422 when name is blank' do
       put "/users/#{user.id}",
           params: { name: '   ' },
           headers: auth_headers(user)
 
-      expect(response).to have_http_status(:bad_request)
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(json.fetch('errors')).to include(
+          'name' => ['名前は必須です．'])
     end
 
     it 'updates name and returns user slice' do

frontend/src/lib/apiErrors.test.ts

@@ -0,0 +1,79 @@
+import { describe, expect, it, vi } from 'vitest'
+
+const api = vi.hoisted (() => ({
+  isApiError: vi.fn (),
+}))
+
+vi.mock ('@/lib/api', () => api)
+
+describe ('extractValidationError', () => {
+  it ('extracts field and base errors from 422 validation responses', async () => {
+    api.isApiError.mockReturnValueOnce (true)
+
+    const { extractValidationError } = await import ('@/lib/apiErrors')
+    const validationError = extractValidationError<'name'> ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      { name: ['名前は必須です．'] },
+          base_errors: ['全体エラー'],
+        },
+      },
+    })
+
+    expect (validationError).toEqual ({
+      message:     '入力内容を確認してください．',
+      fieldErrors: { name: ['名前は必須です．'] },
+      baseErrors:  ['全体エラー'],
+    })
+  })
+
+  it ('preserves dotted field keys for indexed form rows', async () => {
+    api.isApiError.mockReturnValueOnce (true)
+
+    const { extractValidationError } = await import ('@/lib/apiErrors')
+    const validationError = extractValidationError<'deerjikists.0.platform'> ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          errors:      { 'deerjikists.0.platform': ['プラットフォームを入力してください．'] },
+          base_errors: [],
+        },
+      },
+    })
+
+    expect (validationError?.fieldErrors).toEqual ({
+      'deerjikists.0.platform': ['プラットフォームを入力してください．'],
+    })
+  })
+
+  it ('does not treat 400 bad requests as form validation errors', async () => {
+    api.isApiError.mockReturnValueOnce (true)
+
+    const { extractValidationError } = await import ('@/lib/apiErrors')
+    const validationError = extractValidationError ({
+      response: {
+        status: 400,
+        data:   {
+          type:        'bad_request',
+          message:     'リクエストが不正です．',
+          errors:      {},
+          base_errors: ['リクエストが不正です．'],
+        },
+      },
+    })
+
+    expect (validationError).toBeNull ()
+  })
+
+  it ('ignores non-api errors', async () => {
+    api.isApiError.mockReturnValueOnce (false)
+
+    const { extractValidationError } = await import ('@/lib/apiErrors')
+
+    expect (extractValidationError (new Error ('network'))).toBeNull ()
+  })
+})

frontend/src/lib/apiErrors.ts

@@ -1,5 +1,3 @@
-import toCamel from 'camelcase-keys'
-
 import { isApiError } from '@/lib/api'
 
 export type FieldErrors<T extends string = string> = Partial<Record<T, string[]>>
@@ -19,8 +17,13 @@ export const extractValidationError = <T extends string = string> (err: unknown)
   if (!(isApiError (err)) || err.response?.status !== 422)
     return null
 
-  const data = toCamel ((err.response.data ?? { }) as Record<string, unknown>,
-			{ deep: true }) as RawValidationError
+  const rawData = (err.response.data ?? { }) as Record<string, unknown>
+  const data: RawValidationError = {
+    type:       rawData.type as string | undefined,
+    message:    rawData.message as string | undefined,
+    errors:     rawData.errors as Record<string, string[]> | undefined,
+    baseErrors: rawData.base_errors as string[] | undefined,
+  }
 
   if (data.type !== 'validation_error' && !(data.errors))
     return null

frontend/src/pages/deerjikists/DeerjikistDetailPage.test.tsx

@@ -0,0 +1,72 @@
+import { fireEvent, screen, waitFor } from '@testing-library/react'
+import { Route, Routes } from 'react-router-dom'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
+
+import DeerjikistDetailPage from '@/pages/deerjikists/DeerjikistDetailPage'
+import { buildTag } from '@/test/factories'
+import { renderWithProviders } from '@/test/render'
+
+const tagsApi = vi.hoisted (() => ({
+  fetchDeerjikistsByTag: vi.fn (),
+}))
+
+const api = vi.hoisted (() => ({
+  apiPut:     vi.fn (),
+  isApiError: vi.fn (),
+}))
+
+const toastApi = vi.hoisted (() => ({
+  toast: vi.fn (),
+}))
+
+vi.mock ('@/lib/tags', () => tagsApi)
+vi.mock ('@/lib/api', () => api)
+vi.mock ('@/components/ui/use-toast', () => toastApi)
+
+const renderPage = () =>
+  renderWithProviders (
+      <Routes>
+        <Route path="/tags/:id/deerjikists" element={<DeerjikistDetailPage/>}/>
+      </Routes>,
+      { route: '/tags/7/deerjikists' },
+  )
+
+describe ('DeerjikistDetailPage', () => {
+  beforeEach (() => {
+    vi.clearAllMocks ()
+    api.isApiError.mockReturnValue (false)
+  })
+
+  it ('shows indexed validation errors returned for deerjikist rows', async () => {
+    tagsApi.fetchDeerjikistsByTag.mockResolvedValueOnce ({
+      tag:         buildTag ({ id: 7, name: 'deerjika', category: 'deerjikist' }),
+      deerjikists: [{ platform: null, code: 'abc' }],
+    })
+    api.isApiError.mockReturnValue (true)
+    api.apiPut.mockRejectedValueOnce ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      { 'deerjikists.0.platform': ['プラットフォームを入力してください．'] },
+          base_errors: [],
+        },
+      },
+    })
+
+    renderPage ()
+
+    await screen.findByDisplayValue ('abc')
+    fireEvent.submit (screen.getByRole ('button', { name: '更新' }).closest ('form')!)
+
+    await waitFor (() => {
+      expect (api.apiPut).toHaveBeenCalledWith (
+          '/tags/7/deerjikists',
+          [{ platform: null, code: 'abc' }],
+      )
+    })
+    expect (await screen.findByText ('プラットフォームを入力してください．')).toBeInTheDocument ()
+    expect (screen.getByRole ('combobox')).toHaveAttribute ('aria-invalid', 'true')
+  })
+})

frontend/src/pages/materials/MaterialNewPage.test.tsx

@@ -1,11 +1,13 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
-import { describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import MaterialNewPage from '@/pages/materials/MaterialNewPage'
 import { renderWithProviders } from '@/test/render'
 
 const api = vi.hoisted (() => ({
-  apiPost: vi.fn (),
+  apiGet:     vi.fn (),
+  apiPost:    vi.fn (),
+  isApiError: vi.fn (),
 }))
 
 const toastApi = vi.hoisted (() => ({
@@ -16,6 +18,12 @@ vi.mock ('@/lib/api', () => api)
 vi.mock ('@/components/ui/use-toast', () => toastApi)
 
 describe ('MaterialNewPage', () => {
+  beforeEach (() => {
+    vi.clearAllMocks ()
+    api.apiGet.mockResolvedValue ([])
+    api.isApiError.mockReturnValue (false)
+  })
+
   it ('initializes tag from query and submits form data', async () => {
     api.apiPost.mockResolvedValueOnce ({})
 
@@ -35,4 +43,30 @@ describe ('MaterialNewPage', () => {
     expect (formData.get ('url')).toBe ('https://example.com/ref')
     expect (toastApi.toast).toHaveBeenCalledWith ({ title: '送信成功!' })
   })
+
+  it ('shows validation errors for file and url fields', async () => {
+    api.isApiError.mockReturnValue (true)
+    api.apiPost.mockRejectedValueOnce ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      {
+            file: ['ファイルまたは URL は必須です．'],
+            url:  ['ファイルまたは URL は必須です．'],
+          },
+          base_errors: [],
+        },
+      },
+    })
+
+    renderWithProviders (<MaterialNewPage/>)
+
+    fireEvent.change (screen.getAllByRole ('textbox')[0], { target: { value: '虹夏' } })
+    fireEvent.click (screen.getByRole ('button', { name: '追加' }))
+
+    expect (await screen.findAllByText ('ファイルまたは URL は必須です．')).toHaveLength (2)
+    expect (screen.getAllByRole ('textbox')[1]).toHaveAttribute ('aria-invalid', 'true')
+  })
 })

frontend/src/pages/posts/PostNewPage.test.tsx

@@ -1,13 +1,14 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
-import { describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import PostNewPage from '@/pages/posts/PostNewPage'
 import { buildUser } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
 
 const api = vi.hoisted (() => ({
-  apiGet:  vi.fn (),
-  apiPost: vi.fn (),
+  apiGet:     vi.fn (),
+  apiPost:    vi.fn (),
+  isApiError: vi.fn (),
 }))
 
 const toastApi = vi.hoisted (() => ({
@@ -18,6 +19,11 @@ vi.mock ('@/lib/api', () => api)
 vi.mock ('@/components/ui/use-toast', () => toastApi)
 
 describe ('PostNewPage', () => {
+  beforeEach (() => {
+    vi.clearAllMocks ()
+    api.isApiError.mockReturnValue (false)
+  })
+
   it ('blocks guests', () => {
     renderWithProviders (<PostNewPage user={buildUser ({ role: 'guest' })}/>)
 
@@ -55,4 +61,36 @@ describe ('PostNewPage', () => {
     expect (formData.get ('tags')).toBe ('tag1 tag2')
     expect (toastApi.toast).toHaveBeenCalledWith ({ title: '投稿成功!' })
   })
+
+  it ('shows 422 validation errors for post fields', async () => {
+    api.apiGet.mockResolvedValue ([])
+    api.isApiError.mockReturnValue (true)
+    api.apiPost.mockRejectedValueOnce ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      { tags: ['ニコニコ・タグは直接指定できません．'] },
+          base_errors: ['投稿内容を確認してください．'],
+        },
+      },
+    })
+
+    renderWithProviders (<PostNewPage user={buildUser ({ role: 'member' })}/>)
+
+    const checkboxes = screen.getAllByRole ('checkbox', { name: '自動' })
+    fireEvent.click (checkboxes[0])
+    fireEvent.click (checkboxes[1])
+
+    const textboxes = screen.getAllByRole ('textbox')
+    fireEvent.change (textboxes[0], { target: { value: 'https://example.com/post' } })
+    fireEvent.change (textboxes[1], { target: { value: '投稿タイトル' } })
+    fireEvent.change (textboxes[3], { target: { value: 'nico:nico_tag' } })
+    fireEvent.click (screen.getByRole ('button', { name: '追加' }))
+
+    expect (await screen.findByText ('投稿内容を確認してください．')).toBeInTheDocument ()
+    expect (screen.getByText ('ニコニコ・タグは直接指定できません．')).toBeInTheDocument ()
+    expect (screen.getAllByRole ('textbox')[3]).toHaveAttribute ('aria-invalid', 'true')
+  })
 })

frontend/src/pages/tags/TagDetailPage.test.tsx

@@ -1,6 +1,6 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
 import { Route, Routes } from 'react-router-dom'
-import { describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import TagDetailPage from '@/pages/tags/TagDetailPage'
 import { buildTag } from '@/test/factories'
@@ -11,7 +11,8 @@ const tagsApi = vi.hoisted (() => ({
 }))
 
 const api = vi.hoisted (() => ({
-  apiPut: vi.fn (),
+  apiPut:     vi.fn (),
+  isApiError: vi.fn (),
 }))
 
 const toastApi = vi.hoisted (() => ({
@@ -28,9 +29,14 @@ const renderPage = () =>
         <Route path="/tags/:id" element={<TagDetailPage/>}/>
       </Routes>,
       { route: '/tags/7' },
-  )
+)
 
 describe ('TagDetailPage', () => {
+  beforeEach (() => {
+    vi.clearAllMocks ()
+    api.isApiError.mockReturnValue (false)
+  })
+
   it ('loads and displays an editable tag', async () => {
     tagsApi.fetchTag.mockResolvedValueOnce (
         buildTag ({ id: 7, name: '虹夏', category: 'character', aliases: ['drums'] }),
@@ -68,4 +74,28 @@ describe ('TagDetailPage', () => {
 
     expect (await screen.findByRole ('button', { name: '更新' })).toBeDisabled ()
   })
+
+  it ('shows validation errors returned for tag fields', async () => {
+    tagsApi.fetchTag.mockResolvedValueOnce (buildTag ({ id: 7, name: 'old' }))
+    api.isApiError.mockReturnValue (true)
+    api.apiPut.mockRejectedValueOnce ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      { category: ['ニコタグは変更できません．'] },
+          base_errors: [],
+        },
+      },
+    })
+
+    renderPage ()
+
+    await screen.findByDisplayValue ('old')
+    fireEvent.submit (screen.getByRole ('button', { name: '更新' }).closest ('form')!)
+
+    expect (await screen.findByText ('ニコタグは変更できません．')).toBeInTheDocument ()
+    expect (screen.getByRole ('combobox')).toHaveAttribute ('aria-invalid', 'true')
+  })
 })

frontend/src/pages/users/SettingPage.test.tsx

@@ -1,12 +1,13 @@
 import { fireEvent, screen, waitFor } from '@testing-library/react'
-import { describe, expect, it, vi } from 'vitest'
+import { beforeEach, describe, expect, it, vi } from 'vitest'
 
 import SettingPage from '@/pages/users/SettingPage'
 import { buildUser } from '@/test/factories'
 import { renderWithProviders } from '@/test/render'
 
 const api = vi.hoisted (() => ({
-  apiPut: vi.fn (),
+  apiPut:     vi.fn (),
+  isApiError: vi.fn (),
 }))
 
 const toastApi = vi.hoisted (() => ({
@@ -23,6 +24,11 @@ vi.mock ('@/components/users/InheritDialogue', () => ({
 }))
 
 describe ('SettingPage', () => {
+  beforeEach (() => {
+    vi.clearAllMocks ()
+    api.isApiError.mockReturnValue (false)
+  })
+
   it ('shows loading when user is absent', () => {
     renderWithProviders (<SettingPage user={null} setUser={vi.fn ()}/>)
 
@@ -51,4 +57,28 @@ describe ('SettingPage', () => {
     expect (setUser).toHaveBeenCalled ()
     expect (toastApi.toast).toHaveBeenCalledWith ({ title: '設定を更新しました．' })
   })
+
+  it ('shows validation errors returned for the name field', async () => {
+    const user = buildUser ({ id: 11, name: 'old' })
+    api.isApiError.mockReturnValue (true)
+    api.apiPut.mockRejectedValueOnce ({
+      response: {
+        status: 422,
+        data:   {
+          type:        'validation_error',
+          message:     '入力内容を確認してください．',
+          errors:      { name: ['名前は必須です．'] },
+          base_errors: [],
+        },
+      },
+    })
+
+    renderWithProviders (<SettingPage user={user} setUser={vi.fn ()}/>)
+
+    fireEvent.change (screen.getByRole ('textbox'), { target: { value: '' } })
+    fireEvent.click (screen.getByRole ('button', { name: '更新' }))
+
+    expect (await screen.findByText ('名前は必須です．')).toBeInTheDocument ()
+    expect (screen.getByRole ('textbox')).toHaveAttribute ('aria-invalid', 'true')
+  })
 })