Unit test: Foreign exchange market
Let's practice creating and programming mocks in the banking context! Complete the unit test for the ExchangeApp, which
uses the European Central Bank. As you're testing the convertEuroTo() logic, don't mock it. Instead, mock its dependency so that you can check if it works properly!
The necessary JUnit and Mockito packages have been imported for you.
This exercise is part of the course
Introduction to Testing in Java
Exercise instructions
- Create a mock for the
EuropeanCentralBankServer. - Use the correct syntax to program the mock to return
12345.0. - Verify the currency conversion returns the desired output.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
class Main {
public static void main(String[] args) {
launchMockitoTestsAndPrint(ExchangeAppTest.class);
}
}
class ExchangeAppTest {
@Test
void convertEuroTo_convertsTST() {
// Create a mock object for the EuropeanCentralBankServer
EuropeanCentralBankServer bank = ____(EuropeanCentralBankServer.class);
ExchangeApp exchangeApp = new ExchangeApp(bank);
double euroAmount = 100;
// Stub the mock to return a value for given input
____(exchangeApp.convertEuroTo("TST", 100)).____(12345.0);
double tstAmount = exchangeApp.convertEuroTo("TST", euroAmount);
System.out.println("Converted " + euroAmount + " EUR to " + tstAmount + " TST.");
// Assert on the exact expected value of tstAmount
____(1234500, ____);
}
}