Inspired by Test Double Consulting Agency
You work at a credit card company and as a value-add they want to start providing alerts to users when their spending in any particular category is higher than usual.
Paymentis a simple value object with a
Categoryis an enumerable type of a collection of things like “entertainment”, “restaurants”, and “golf”
- For a given
userId, fetch the payments for the current month and the previous month
- Compare the total amount paid for the each month, grouped by category; filter down to the categories for which the user spent at least 50% more this month than last month
- Compose an e-mail message to the user that lists the categories for which spending was unusually high, with a subject like “Unusual spending of $1076 detected!” and this body:
Hello card user!
We have detected unusually high spending on your card in these categories:
* You spent $148 on groceries
* You spent $928 on travel
The Credit Card Company
More details about the goal, caveats, extra credit or solutions: Unusual Spending Kata by Test Double.
Get the code
If your favorite language is missing, feel free to create a pull request. Be sure the maintainer will be happy ;-)
Image by Rachel M. Carmena. It represents a greeting of respect and gratitude made at the beginning and at the end of a kata.