Hi @anallinasrodriguez and thank you for reaching out! 
If you’re referring to the test after completing the introduction course, it just seems that one little step was missed in your registration, which is the enrollment step 
Now that I did the enrollment step for you, you’ll be able to access the test, kindly go through the course again and take some time to read through the material. After you move to the end, you’ll be able to take the test and gain the certificate 
If you’re referring to the verification tests, they are no longer available, our kind @Dalia1 correctly explained how the verification works 
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Let us know if you still need any help 