【再掲】タグの局所記載 (#351) (#380)

#353 を再開できなかったので．

Reviewed-on: #380
Co-authored-by: miteruzo <miteruzo@naver.com>
Co-committed-by: miteruzo <miteruzo@naver.com>

frontend/src/components/PostEditForm.test.tsx

@@ -66,4 +66,27 @@ describe ('PostEditForm', () => {
     expect (onSave).toHaveBeenCalledWith (expect.objectContaining ({ versionNo: 5 }))
     expect (toastApi.toast).toHaveBeenCalledWith ({ description: '更新しました．' })
   })
+
+  it ('preserves duration while the video tag is temporarily removed', () => {
+    const post = buildPost ({
+      videoMs: 180_500,
+      tags:    [
+        buildTag ({ id: 1, name: '動画', category: 'general' }),
+        buildTag ({ id: 2, name: 'general-tag', category: 'general' }),
+      ],
+    })
+
+    render (<PostEditForm post={post} onSave={vi.fn ()}/>)
+
+    expect (screen.getByRole ('spinbutton')).toHaveValue (180.5)
+
+    const tags = screen.getAllByRole ('textbox')[2]
+    fireEvent.change (tags, { target: { value: 'general-tag' } })
+    expect (screen.queryByRole ('spinbutton')).not.toBeInTheDocument ()
+
+    fireEvent.change (tags, {
+      target: { value: '動画 general-tag' },
+    })
+    expect (screen.getByRole ('spinbutton')).toHaveValue (180.5)
+  })
 })