Your homework task will be to create an application for exchanging currencies. Take a look how the app should look like at https://scene.zeplin.io/project/6328362a0632f614ccf818da. Screen images are to get better understanding how everything should work and you don't have to make it look exactly the same. However, if you wish to use resources (images, colors) from the design please email us your Zeplin email. The user has a multi-currency account with starting balance of 1000 Euros (EUR). He can convert any currency to any if the rate is provided by the API but the balance can't fall below zero. Create an input where the user will enter amount, picker for currency being sold and a picker for currency being bought. For example, user inputs 100.00, picks Euros to sell and Dollars to buy. User then clicks Submit button, a message is shown You have converted 100.00 EUR to 110.30 USD and now the balance is 900.00 Euros and 110.30 US Dollars. Also, there may be a commission fee for the currency exchange operation. The first five currency exchanges are free of charge but afterwards they're charged 0.7% of the currency being traded. The commission fee should be displayed in the message that appears after the conversion. For example: "You have converted 100.00 EUR to 110.00 USD. Commission Fee - 0.70 EUR." The commission fee should be deducted from each currency balance separately. Currency exchange rates should be synchronized every 5 seconds

• Kotlin
• MVVM
• Room
• Coroutines
• View Binding
• Koin
• Retrofit
• Gson
• Mockito
• JUnit
• Material

Written tests for 2 use cases CalculateCommissionAndSubmitTransaction and CalculateReceivedAmountUseCase

• the task must be done in Kotlin
• there are no strict restrictions on time
• third-party libraries, tools, frameworks can be used
• the system should be maintainable & expandable:
• • a clear relationship between the parts of the code
• • the code is understandable, simple, readable
• • the addition of a new functionality or an existing change should not require rewriting the entire system
• • adding new currency should be easy
• • provide for the possibility of expanding the calculation of a more flexible commission. It is possible to come up with various new rules, for example - every tenth conversion is free, conversion of up to 200 Euros is free of charge etc.
• balance must be visible somewhere in the UI
• balance can't be negative after the conversion
• the code should conform to the selected code standards (e.g. google java style guide, square java style guide).
• it would be best to test the app before the submission of code.

• all requirements are met
• code quality
• knowledge of Android ecosystem - libraries, frameworks
• knowledge of best practices, design & architecture patterns
• (insanely) great UI/UX is an advantage
• providing UnitTests is a plus