Disclaimer

The puzzle used for this kata is taken from Advent Of Code 2021 (Day 2 - Part 2). All credits goes to AOC's team for their incredible work.

The TCR Utility Tool I'm using is an adaptation on Murex's one that can be found in one of my repos.

Kata

The goal of this kata is to allow people to get familiar with TCR (Test && Commit || Revert), and experience it in a safe context as a pair or mob.

You need to figure how to pilot this submarine.

It seems like the submarine can take a series of commands like forward 1, down 2, or up 3:

down X increases your aim by X units.
up X decreases your aim by X units.
forward X does two things:
- It increases your horizontal position by X units.
- It increases your depth by your aim multiplied by X.

Note that since you're on a submarine, down and up affect your aim and do the opposite of what you might think.

The submarine seems to already have a planned course. You should probably figure out where it's going. For example:

Your horizontal position, depth and aim all start at 0. The steps above would then modify them as follows:

forward 5 adds 5 to your horizontal position, a total of 5.
- Because your aim is 0, your depth does not change.
down 5 adds 5 to your aim, resulting in a value of 5.
forward 8 adds 8 to your horizontal position, a total of 13.
- Because your aim is 5, your depth increases by 8*5=40.
up 3 decreases your aim by 3, resulting in a value of 2.
down 8 adds 8 to your aim, resulting in a value of 10.
forward 2 adds 2 to your horizontal position, a total of 15.
- Because your aim is 10, your depth increases by 2*10=20 to a total of 60.

After following these instructions, you would have a horizontal position of 15 and a depth of 60.

The goal of the kata is to make all acceptance tests pass following Test-Driven Development and using the TCR Utility Tool.

Create a branch of your own so you don't push all your commits on the main branch!

Follow the Test-Driven Development approach.
Use the TCR Utility Tool with the according mode (Driver|Navigator)
- Here's the command line to use :

tcrw -p -t xunit

ISubmarine interface cannot be changed.
Submarine component should have an empty constructor.
Handle empty/wrong input so they don't affect the state of the submarine without stopping the process.
When an acceptance test pass, change its tag to 'Acceptance'.
Apply SOLID principles whenever possible
Think about design (not sure all the code should be in the Submarine class, right?).
- For example, grouping domain knowledge inside value objects might be a good idea.
Refactor the code like it's production code.

Baby-steps. If you think you're going small, think smaller.
You should have TCR generating commits often, like every few minutes.
If you spend more than 5 minutes on an implementation, discard your changes and start with another approach.
The submarine's behavior is detailed in the summary.
Try to implement pure functions for better predictability.
Use acceptance tests to follow your progress.