Collin: You always test before the code goes into production. If you don't, you're asking for your customers to have a buggy, non-working experience.
me: How do you test?
Collin: Usually coders have three “environments”: development, test, and production. Development can be anything, but test is supposed to be just like production, except only the developers can see it. You write test cases that put the code into a certain state and ensures that whatever you ask the code to do - you get the results you expect. One of the metrics programmers use is code coverage, which maps what portions of your code (line by line) are used in your tests. One of the major coding paradigms is “Red Green Coding”, where you write the tests first, and they fail, then you go back and implent the features until they pass. This keeps you from faking passing tests.
me: (vague idea of what he's discussing, but horrible flashbacks of my programmer/IT days kick in and mind starts to shut down)
Collin: It's like greasing a baking pan before cooking, rather than saying afterwards, “I meant to leave that stuck to the bottom.”
me: Ohhhhhhh. NOW I get it.