The test is going well. We haven't had any problem.
Why do we use "haven't had" instead of "didn't have"?
[STRIKE]could you please clear it out straightaway[/STRIKE].
As bhai said, the first sentence makes it clear that the test is still underway. If it helps, imagine that it reads "We haven't had any problems yet" or "We haven't had any problems so far".
If it started "The test went well", showing that the test is over, it could be followed by "We didn't have any problems".
Please don't ask us to reply "straight away" (note though, that it is written as two words). We are all volunteers. We will get to your post as and when we have the time.