A Nigerian software engineer, Celestine Omin claims that he was made to sit a written test by US airport immigration officers in order to prove his skills.

Omin, 28, who works with Andela, a tech start-up, landed in New York's JFK airport last Sunday after a 24-hour flight from Nigeria. He had been granted a short-term visa to work with First Access, a financial technology company in Manhattan district, New York. 

According to him, after being asked a series of questions by a US Customs and Border Protection officer, he was taken to a small room for further checks. Another hour passed before a different customs officer came in, gave him a piece of paper and paper and told him to answer the following questions to prove he is actually a software engineer: 
"Your visa says you are a software engineer. Is that correct?" an officer is reported to have asked Mr Omin." 
Write a function to check if a Binary Search Tree is balanced. What is an abstract class, and why do you need it?"
After he handed back his answers, he was told by the officer that they were wrong. He said he presumed he was required to provide "the Wikipedia definition" for the question.

A little later, the officer told him: "Look, I am going to let you go, but you don't look convincing to me,"
"I didn't say anything back. I just walked out." said Omin.
He also found out later found that border protection officers had phoned Andela to verify his story.

Read the full interview here and also see his tweets below...