Ki take home exercise

Notes on submission

A lean approach was taken to the task, see comments
The original pom.xml file had a duplicate dependency that needed removal for the task to run

Background

The Ki website allows customers to open an account and purchase shares in one or more funds. Before a customer can buy shares, they top up their account with a desired amount, using a debit card.

The website is supported by an underlying investment platform, consisting of modules that each perform a specific role. Each module is a separate package, installed on the platform as a dependency. One of these modules is tasked with processing an incoming payments CSV file, then generating a share order CSV, consumed by another module.

This report contains the customer_id and the number of shares their payment(s) will purchase, given the share price.

"customer_id","shares"
"123","100"
"987","3400"

For development, the module can be invoked with the LocalRunner class, which simulates how it is integrated with the investment platform. This is configured as the main class of the package. To run this locally, build the project with Maven:

mvn package

You can now call the JAR file directly:

java -jar target/ki-takehome-kotlin-1.0-SNAPSHOT.jar <path_to_payments_csv> <source> <share_price>

To see example output:

java -jar target/ki-takehome-kotlin-1.0-SNAPSHOT.jar card_payments_example.csv card 1.20

Exercise

Some customers have indicated they would prefer to top up their account by making a bank transfer, rather than using their debit card.

Update the com.ki.services.PaymentProcessor class to support both card and bank transfer payments. We will receive a separate CSV file from our payment provider, in a similar format to card payments:

customer_id,date,amount,bank_account_id
789,2018-10-25,900,20
345,2018-11-03,900,60

Unlike card payments, our payment provider will only update us once a bank transfer has been successfully processed.

Remember, the module is installed on the platform as a dependency, therefore the API to both the PaymentProcessor and ShareEngine service classes must not change.

You can check your implementation by using the example CSV:

java -jar target/ki-takehome-kotlin-1.0-SNAPSHOT.jar bank_payments_example.csv bank 1.20

This should produce the result:

"customer_id","shares"
"789","735"
"345","735"

Tests

You can run the tests from the root of the project with:

mvn test

Notes