Debugging 2

Tightening the loop and getting visibility (on the web).

Learning Objectives

Define 'debugging' as the process of eliminating bugs from an expected program output
Explain the mantra 'Tighten the loop; Get visibility'
Use the mantra to resolve bugs across the web stack.

In this program, there are many bugs. You have three objectives:

Find the bugs and fix them. You can assume that the tests describe the correct behaviour.
You need to get all the tests passing.
You need to run the app and make sure it works.

Last week, you practiced this debugging method:

Tighten the loop (find the exact line the bug is coming from)
Get visibility (use p to inspect everything to help you home in on the exact line)
Once you know the one thing that is wrong, out of place, misspelled, or not giving you what you expect, try to fix it.

This week, you'll build these skills. You'll practice:

Tightening the loop across the whole web stack: from the browser, to a template, to a controller, to a Ruby object, to a test.
Using error messages and p to get visibility in templates, controllers, Ruby objects and tests.

Run the app with shotgun. This will automatically reload your changes so you don't need to restart your server on each code change.
Browse the app at the URL in your server logs.

As a person
So I can feel more relaxed
I want to state a thing I'm struggling with and see it shouted by the table flip emoji

As a person
So I can feel more relaxed
I want to see a random happy emoji on the home page