Blood in the Water - why bug 'feeding frenzies' are a good sign

I've been fortunate that my company has enjoyed a successful year and I've been in a position to take on new testers. As the team has grown an interesting phenomenon has become more apparent relating to patterns of bugs that are raised against our system . At first glance it is an apparently worrying trend, however if we look deeper I think it is something that gives me confidence that we're hiring the right folks and ultimately provides an indication of a healthy testing culture.

A feeding frenzy

We enjoy a highly collaborative relationship between the testers and developers across the team. One way that this manifests itself is through open discussion on any issues that we find through testing. Rather than limiting our communication to playing tennis with the bugs database, we'll discuss emerging problems openly with developers. We'll chat about the risks relating to an issue and decide whether to tackle immediately or raise in the tracking system for future prioritisation. Most importantly, though, we'll try to identify the contributory factors behind the issue to pin down exactly what has caused it to occur.

The phenomenon that I find interesting is that, after one of the testers in the team has been discussing an issue in the office, over the next few hours or days I will often see more bugs which have common characteristics to the original issue being raised. The interesting part is that these will come, not from the original tester, but by other members of the team not immediately connected to the original discussion. These will always differ sufficiently from the original issue to not be mere bug plagiarism, but I'll see a clear correlation between the original bug and the subsequent ones to know that the occurrence of the latter was directly influenced by the former.

A Sign of Distraction?

So are the testers getting distracted? That is one way of looking at it. Another is that they are simply copying each other, but given the fact that I place no value on the number of issues a tester raises, this would be pointless. I take a different view. An extremely useful source but rarely mentioned source of testing information is simply listening in on conversations that take place in the office, eavesdropping if you will. If you were to ask me to list my top 10 most powerful testing techniques then eavesdropping would probably rank in there somewhere. When a crop of issues is raised around an area which has recently been the subject of discussion this tells me that the testers in my team have their ears open and are listening to the information that is being generated and shared between their colleagues daily. Not only that but they are using that information, processing it and applying it to their testing.

The Birth of a Heuristic

Testers use heuristics to generate testing ideas. These will be based on combined information from a variety of sources including documentation, conversations, articles and publications, testing theory and simple prior experience. Many of the 'major' issues that I and my team have identified in my system over recent years have been rooted very much in the specifics of the application and its design rather than in programmatical error. The use of context relevant testing heuristics has certainly allowed us to identify and resolve such issues that may otherwise have gone undetected through more traditional 'requirements traceability matrix' based approaches (As I discussed in this post an effective way of sharing these heuristics between team members is to generate and maintain a team heuristics sheet on a Wiki). The fact that a discussion around a new problem area can result in a flurry of related issues being generated to me is an indication that the team are mentally processing new information to generate new heuristics, and then using their instincts to identify other areas of the system where their application might be relevant. This process of heuristic evolution via 'mutation' to me is a valuable sign of critical thinking on the part of my team and is certainly a positive behaviour that should be encouraged. This is why, whenever I see a series of issues being raised within the team that looks like the testers have been copying each others homework, it always makes me smile. After all, you can't turn off instinct in the best hunters, and when there's blood in the water expect a feeding frenzy to follow.

Image: Wikipedia