Debugging by induction Book: The Art of Software Testing Code Maker http://codesmaker.blogspot.com

1. Prepared By Waqar Ali
Software Engineer
Abasyn University Peshawar
Debugging By Induction
codesmaker.blogspot.com

2. Debugging by Induction
Many errors can be found by using a disciplined thought pro
cess without ever going near the computer.
• One such thought process is induction which can figure out
the solution to a problem
• You start with your own experience and then generalize a rule
Introduction

3. What?
So what is meant by debugging by induction?
• Induction is a debugging strategy
• In other words it is called reasoning or thoughtful strategy
Induction debugging start with the symptoms of the error,
possibly in the result of one or more test cases, and looking for
relationships among the symptoms, the error is often
uncovered.

4. Example
Let’s take an General Example
For example, because the last few times I cut my hair, it grew
back. Inductive reasoning allows me to generalize that after I
cut my hair it will always grow back.
For example, The last ten times I touched the hot stove
I burned my hand. I bet every time I touch the hot stove my han
d will be burned.

5. How
How to perform induction strategy?
To perform induction strategy, a number of steps are followed, which are listed below.
1. Locating relevant data: All the information about a program is collected to
identify the functions, which are executed correctly and incorrectly.
2. Organizing data: The collected data is organized according to importance.
The data can consist of possible symptoms of errors, their location in the
program, the time at which the symptoms occur during the execution of the
program and the effect of these symptoms on the program.

6. Form
This is a form used for organizing the data

7. Cont…
3. Devising hypothesis: The relationships among the symptoms
are studied and a hypothesis is devised that provides the hints
about the possible causes of error.
4. Proving hypothesis: In the final step, the hypothesis needs to
be proved. It is done by comparing the data in the hypothesis
with the original data to ensure that the hypothesis explains the
existence of hints completely. In case, the hypothesis is unable
to explain the existence of hints, it is either incomplete or
contains multiple errors in it.

8. Cont…
5. Fix the problem:
• You can proceed with fixing the problem once you complete th
e previous steps.
• By taking the time to fully work through each step, you can
feel confident that your fix will correct the bug.
• Remember though, that you still need to perform some type of
regression testing to ensure your bug fix didn’t create
problems in other program areas.
• As the application grows larger, so does the likelihood
that your fix will cause problems elsewhere.