That means your unit test failed. You will be able to know why it failed by looking at error message around this output.
So, shall I change the original value (20) by zero ?
If what you mean is to change the test I would say no. Please consider that your code may not be correct before changing the test code.
But it is working by changing the value
Yep. But if you change the test how can you know that your code was right?
Like if you got a question wrong on the SATs and then went and modified the question so that your answer was right.
I am really sorry!.
I was not familiar with Assert class.
After reading about it I came to know everything. once again I am sorry
No need to be sorry. Really happy you got it figured out!