Tester or developer?

In 1989. I started to learn my first programming language at high school. It was pascal. Unfortunately, we learned it by writing our programs on a sheet of paper , and when we had a computer lab scheduled for us we retyped those programs and executed them. In programs we had to implement various algorithms for creating various shapes by printing '*' on computer screen. My primary learning goal was to understand those algorithms. At that time I didn't know where to look for alternative learning materials. One of the reasons was that at that time I had been learning English language for just one year. But, there was one guy, Mirko, in my class that was a way ahead of me. He was taking about programming craft. He was self learner. He knew English language very well. 
Mirko: "Your are not finished with your program when you implement algorithm correctly. This is just the beginning. For example, you have also to consider memory consumption of your program.
At that moment I started my testing learning path.