06. Solution: Writing Unit Tests

Solution: Writing Unit Tests

Writing a Unit Test

You should have created a class called TotalsCalculatorTest in the com.udacity.cart.service package of the src/test/java directory. Aside from the awkward design of the class under test, this test is fairly simple. We create a new TotalsCalculator, populate a list of CartItems, and then use the calculator to return a CartTotals. Then we use assertAll to execute two different assertEquals methods on the subtotal and taxes. Note that the assertEquals(double) method takes an additional parameter specifying the acceptable variance, because doubles are floating point numbers that will rarely be 100% equal.

public class TotalsCalculatorTest {

    @Test
    public void getTotals_givenMultipleItems_sumsPriceAndTax() {
        // Arrange
        TotalsCalculator totalsCalculator = new TotalsCalculator();

        List<CartItem> itemList = List.of(
            new CartItem("Soda", 3.00, 0.50),
            new CartItem("Small peperoni pizza", 6.00, 0.60),
            new CartItem("Fries", 2.00, 0.10)
        );

        // Act
        CartTotals totals = totalsCalculator.getTotals(itemList);

        // Assert
        assertAll("Totals match",
            () -> assertEquals(11.0, totals.getSubtotal(), 0.001),
            () -> assertEquals(1.2, totals.getTaxes(), 0.001)
        );
    }
}