How do you encourage junior developers in the company to write tests?

This week I had a very interesting conversation with a beginner developer looking for his first job opportunity. He asked me what the real importance of tests is in everyday life and how to structure test cases, how to detect possible test cases. It was an interesting conversation. I encouraged him to continue studying hard about tests and techniques. But and you? How would you do that? I really want to know your opinion! 😃