The main purpose of this project is learning and sharing. I'm learning and I'm hoping by sharing my adventure it may help you learn. If nothing else, maybe it will at least entertain you. Watching me make bonehead mistakes and hopefully discover them and fix them may be slightly entertaining. I have enabled Discussions in this project if you would like to drop a line or ask a question.
- Create a working example of Minimum CD. See Continuous Delivery Pipelines: Dave Farley Style in this project.
- Demonstrate a TDD test driven design approach to developing a small project
- Demonstrate an ATDD acceptance test driven design approach.
Releases can be found on Box.com in the vending-machine-project-releases folder. The application is a NodeJS console app that runs in your terminal. You will need to install NodeJS in order to run it. Install Node version20.x or greater from NodeJS Org. The app doesn't do much right now but if you want to execute it simply unzip the release then in the root directory
node bin/indexISC License
THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
I think the the vending machine code kata is particularly interesting to me for two reasons. Firstly, it is a little larger than other katas like FizzBuzz. Secondly, the first assignment in a software engineering class at university back in the day was to implement a vending machine in code. I was really disappointed that my team received a grade of B. We failed to understand that we were supposed to implement a real-time system. The assignment didn't mention a real-time system, but to be fair, we didn't ask. I learned a valuable lesson and ended up with an A for the class at the end so no damage. However, I think it will be fun to correct past mistakes.
See the developer's log in the design directory in this project for a developer's log along with supporting documents. Here's where I'm posting status updates as I go along. Often I will put in links so you can see how the code was at the time of writing the status. My hope is this will help show how the code evolves or maybe (I hope not) devolves over time.
Viewing the developer's log via GitHubs file viewer works well but it's a better experience viewing the other design documents via github.io which will enable the hyperlinks in the PDF documents. Here's the links for your convenience
Instructions as presented at https://cyber-dojo.org
In this exercise you will build the brains of a vending machine. It will accept money, make change, maintain inventory, and dispense products. All the things that you might expect a vending machine to accomplish.
The point of this kata to to provide a larger than trivial exercise that can be used to practice TDD. A significant portion of the effort will be in determining what tests should be written and, more importantly, written next.
As a vendor
I want a vending machine that accepts coins
So that I can collect money from the customer
The vending machine will accept valid coins (nickels, dimes, and quarters) and reject invalid ones (pennies). When a valid coin is inserted the amount of the coin will be added to the current amount and the display will be updated. When there are no coins inserted, the machine displays INSERT COIN. Rejected coins are placed in the coin return.
NOTE: The temptation here will be to create Coin objects that know their value. However, this is not how a real vending machine works. Instead, it identifies coins by their weight and size and then assigns a value to what was inserted. You will need to do something similar. This can be simulated using strings, constants, enums, symbols, or something of that nature.
As a vendor
I want customers to select products
So that I can give them an incentive to put money in the machine
There are three products: cola for $1.00, chips for $0.50, and candy for $0.65. When the respective button is pressed and enough money has been inserted, the product is dispensed and the machine displays THANK YOU. If the display is checked again, it will display INSERT COIN and the current amount will be set to $0.00. If there is not enough money inserted then the machine displays PRICE and the price of the item and subsequent checks of the display will display either INSERT COIN or the current amount as appropriate.
As a vendor
I want customers to receive correct change
So that they will use the vending machine again
When a product is selected that costs less than the amount of money in the machine, then the remaining amount is placed in the coin return.
As a customer I want to have my money returned So that I can change my mind about buying stuff from the vending machine
When the return coins button is pressed, the money the customer has placed in the machine is returned and the display shows INSERT COIN.
As a customer
I want to be told when the item I have selected is not available
So that I can select another item
When the item selected by the customer is out of stock, the machine displays SOLD OUT. If the display is checked again, it will display the amount of money remaining in the machine or INSERT COIN if there is no money in the machine.
As a customer I want to be told when exact change is required So that I can determine if I can buy something with the money I have before inserting it
When the machine is not able to make change with the money in the machine for any of the items that it sells, it will display EXACT CHANGE ONLY instead of INSERT COIN.