Your goal is to create two functions in Golang that verifies the correctness of a supplied credit card number and determine its card scheme. You can decide on the function's signature and types. It is mandatory that you add automated tests.
When ready, push your code.
The following algorithm can be used to check validity of a card number:
- Starting from the right, replace each second digit of the card number with its doubled value
- When doubling a digit produces a 2-digit number (e.g 6 produces 12), then add those 2 digits (1+2 = 3)
- Sum up all the digits
The card number is valid if the sum is divisible by 10
Example: Let's check if 5237 2516 2477 8133 is a valid credit card number.
- Double each second digit: 10 2 6 7 4 5 2 6 4 4 14 7 16 1 6 3
- Add 2-digit numbers: 1 2 6 7 4 5 2 6 4 4 5 7 7 1 6 3
- Sum up all the digits: 70
70 is divisible by 10, so 5237 2516 2477 8133 is a valid credit card number
Please implement a function that given a credit card number returns if it is valid
Card Scheme (Visa, MasterCard, JCB, etc) can be detected by the first digits of the card and the length of the card.
Example
| Scheme | Ranges | Number of Digits | Example number |
|---|---|---|---|
| American Express | 34,37 | 15 | 378282246310005 |
| JCB | 3528-3589 | 16-19 | 3530111333300000 |
| Maestro* | 5018, 5020, 5038, 5893, 6304, 6759, 6761, 6762, 6763, 676770, 676774 | 12-19 | 6759649826438453 |
| Visa | 4 | 13,16,19 | 4012888888881881 |
| MasterCard | 2221-2720, 51-55 | 16 | 5105105105105100 |
Based on https://en.wikipedia.org/wiki/Payment_card_number
Please implement a function that given a credit card number returns its card scheme.
To run code with single example, run in command line: go run main.go.
To run whole test suite, run in command line: go test ./...
Checking bank scheme was implemented only for card providers mentioned in description
(Amex, JCB, Maestro, Vica, Mastercard).
It's possible to easily extend solution for additional card providers by extending bankSchemeMap with
new entry with provider name and appropriate regular expression.
Defined Maestro range looks outdated at this point, so newer range was implemented based on notes from Wikipedia (https://en.wikipedia.org/wiki/Payment_card_number). There are providers like Dankort and China UnionPay that starts with 6. Also in 2022 new ranges for Maestro UK were introduced.
It was decided to create enum for Bank Schemes, so returned value is integer, not string. It's easy to change that using String() function provided for the enum.
Values for reference:
| Card Provider | Enum value |
|---|---|
| AmericanExpress | 1 |
| JCB | 2 |
| Maestro | 3 |
| Visa | 4 |
| MasterCard | 5 |
| Undefined | 0 |
As I am more experienced with Python than Go, some parts might be not strictly following Go conventions. I'm open to discussion on this.