How To Prepare Test Case For Captcha?

Test Cases for CAPTCHA:
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1. Ensure that the CAPTCHA code screen should be viewable.
2. Ensure that the CAPTCHA code should be in Image format.
3. Ensure that the CAPTCHA code should be reusable.(able to get new code by clicked link)
4. Ensure that the CAPTCHA code should generate new code once the page is refreshed.
5. Ensure that the CAPTCHA code should generate new code once entered the wrong code.
6. Ensure that the CAPTCHA code should not able to copy/paste.
7. Ensure that the CAPTCHA code should be Case Sensitive or vice versa(According to the Requirement).
8. Ensure that the CAPTCHA code should not distruot the other fields in the form once entered wrong.(Other form fields should not clear)
9. Application should not accept the Invalid CAPTCHA code on form feed and should display proper alert message.
10. Application should accept the Valid CAPTCHA code on form feed.