The guide for the novice debugger
table of contents
- What is debugging?
- Why do we have bugs?
- Why debugging is hard?
- Approaching a problem
- Debugging strategies
- Debugging Tips and tricks
- How to fix a bug
Software developers spend 50% of their time debugging
Debugging is the process of finding and resolving defects or problems within the program that prevent correct operation of computer software or a system
what is debugging?
Debugging is simply a domain-specific term for problem solving
what is debugging?
We must stop interpret bugs as failures of individual programmers
what is debugging?
solving bugs is an important part of the learning process.
what is debugging?
Why do we have bugs in the first place?
Software errors result when
chains of cognitive breakdowns
are formed over the course of programming activity.
why do we have bugs?
most bugs are caused by the assumptions we didn't realize we were making
why do we have bugs?
What makes some developers better than others at debugging?
-
Experience
-
Good problem-solving skills
What makes good debuggers?
Fixed mindset vs Growth mindset
What makes good debuggers?
Why debugging is hard?
Debugging is a malleable skill, that becoming better at it requires you to work hard at the edge of your ability.
why debugging is hard?
If you don't fully understand a problem and then implement a "provably correct" solution based on incomplete understanding, debugging will still be required
why debugging is hard?
The hardest part of finding a solution is actually understanding the problem
Your goal is to determine precisely what is not working and define it
why debugging is hard?
A lot of things can go wrong
- Compiler/transpiler
- Bundling
- Transformations
- Editor/IDE
- extensions
- Tests
- Network
- Virtual Machine
- Browser
- Language
- Hardware
- API
why debugging is hard?
Approaching a problem
Be persistent
Approaching a problem
Be curious
(be ready to learn new subjects)
Approaching a problem
Be ready to make some mess in the codebase
Approaching a problem
Always verify your assumptions
Approaching a problem
Make a progress by ruling out hypothesizes and isolate the problem
Approaching a problem
Take a break if needed
Approaching a problem
Don't be afraid of node_modules
Approaching a problem
There is no single algorithm that leads to the understanding of a problem, there are multiple strategies
Generate a hypothesis
debugging strategies
Follow the stack trace
debugging strategies
simplify/isolate the problem
debugging strategies
Google the error message
debugging strategies
The debugger should be your last resort
Use the debugger
Use the debugger
debugging strategies
Some debugging tips and tricks
Can be reproduced on a fresh clone + install?
(probably problem with dependencies)
debugging tips and tricks
Can be reproduced on a different machine
(probably problem with the environment)
debugging tips and tricks
Verify what exactly is causing the bug
1. Get to a place in history when everything was fine
2. Recreate the problem a single step.
debugging tips and tricks
How to fix a bug?
-
Write a test that reproduces the problem and fails.
-
Make it pass (by modifying production code)
If (needed && possible)