Tag Archives: testing

What is a bug?

Buggy software doesn’t work. According to wikipedia

A software bug is an error … in a computer program or system that causes it to produce an incorrect or unexpected result, or to behave in unintended ways. Most bugs arise from mistakes and errors made by people in either a program’s source code or its design ...

When something is wrong with a program, we rarely hear of it having one bug — we hear of it having many bugs. I’m wondering: Where does one bug end and the next bug begin?

To answer this question, we need an operational definition of a bug, not the indirect notion present in the Wikipedia quote. 1

This post starts to explore such a definition, but I’m not satisfied with it yet — I’m hoping you will provide your thoughts in the comments to move it forward.

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  1. Andreas Zeller, in his book Why Programs Fail, prefers the term defect to bug since the latter term is sometimes used to refer to erroneous behavior, rather than erroneous code. I stick with the term bug, in this post, and use it to mean the problematic code (only).


Filed under Semantics, Software engineering