Fit for Developing Software: Framework for Integrated Tests

35.1. Testing Directly

As we saw in Chapter 31, one approach to implementing fixtures for calculation tests is to call a specific method within the application that does only that calculation for a business rule. For example, consider the fair charge table from Chapter 16 shown again in Figure 35.1.

The DoFixture class CalculateFairCharge that Neo and Emily developed is shown in Listing 35.1.^[1]

^[1] This makes use of the application class Rates, which manages the charging rates of rentals.

This method simply returns a CalculateFixture object of class FairCharge, as shown in Listing 35.2. Class FairCharge uses a Duration, which encodes the hours, days, and weeks of a rental. Duration values in this and the following Fit tables are handled automatically by the FitLibrary fixtures because a static parse() method exists in class Duration. This method translates a String into a Duration.

Listing 35.1. CalculateFairCharge.java

public class CalculateFairCharge extends DoFixture { public Fixture ratesDollarPerHourPerDayPerWeek(Money perHour, Money perDay, Money perWeek) { return new FairCharge(new Rates(perHour,perDay,perWeek)); } }

Listing 35.2. FairCharge.java

public class FairCharge extends CalculateFixture { private Rates rates; public FairCharge(Rates rates) { this.rates = rates; } public Duration fairDuration(Duration duration) { return rates.fairDuration(duration); } }

The Rates object encodes the business rule. This object is used in FairCharge to calculate the fair duration, based on the actual charge rates.