Develop command line interface (CLI) to simulate interaction with a retail bank. Implement the following commands:
| Command | Description |
|---|---|
login <client> |
Login as client. Creates a new client if not yet exists. |
topup <amount> |
Increase logged-in client balance by amount. |
pay <another_client> <amount> |
Pay amount from logged-in client to another_client, maybe |
| in parts, as soon as possible. |
Your code should handle edge cases and be covered with tests. Please document your assumptions.
Given clients Alice and Bob with initial balances (100, 80):
| Action | Result Balances |
|---|---|
| Bob pays Alice 50 | (150, 30) |
| Bob pays Alice 100 | (180, 0) with Bob owing 70 |
| Bob tops up 30 | (210, 0) with Bob owing 40 |
| Alice pays 30 to Bob | (210, 0) with Bob owing 10. Debt has further decreased |
| Bob tops up 100 | (220, 90) |
Console output of your implementation should contain as least all of the output of the following scenario. Feel free to add extra output as you see fit.
> login Alice
Hello, Alice!
Your balance is 0.
> topup 100
Your balance is 100.
> login Bob
Hello, Bob!
Your balance is 0.
> topup 80
Your balance is 80.
> pay Alice 50
Transferred 50 to Alice.
Your balance is 30.
> pay Alice 100
Transferred 30 to Alice.
Your balance is 0.
Owing 70 to Alice.
> topup 30
Transferred 30 to Alice.
Your balance is 0.
Owing 40 to Alice.
> login Alice
Hello, Alice!
Owing 40 from Bob.
Your balance is 210.
> pay Bob 30
Owing 10 from Bob.
Your balance is 210.
> login Bob
Hello, Bob!
Your balance is 0.
Owing 10 to Alice.
> topup 100
Transferred 10 to Alice.
Your balance is 90.