March 2015
Intermediate to advanced
600 pages
21h 54m
English
Content preview from Ruby Cookbook, 2nd Edition
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Chapter 19. Testing, Debugging, Optimizing, and Documenting
The recipes in previous chapters focus on writing code to do what you want. This chapter focuses on verifying that your code really works, and on fixing it when it breaks. We start off simple and move to more advanced debugging techniques.
What happens when your program has a bug? The best-case scenario is that you discover the bug before it affects anyone, including other developers. That’s the goal of unit tests (Recipe 19.7). Ruby and the Ruby community promote a philosophy of writing automated tests as (or even before) you write the corresponding functionality. At every stage of development, you know that your program works, and if you make a change that breaks something, you know about it immediately. These tests can replace much boring manual testing and bug hunting.
Suppose a bug slips past your tests, and you only discover it in production. How’s it going to manifest itself? If you’re lucky, you’ll see an exception: a notification from some piece of Ruby code that something is wrong.
Exceptions interrupt the normal flow of execution, and, if not handled, will crash the program. The good news is that they give you a place in the code to start debugging. It’s worse if a bug doesn’t cause an exception, because you’ll only notice its byproducts: corrupt data or even security violations. We show code for handling exceptions (Recipes 19.3 and 19.4) and for creating your own (Recipe 19.2).
Successful debugging means ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.