JamManufacturerTest

import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;

public class JamManufacturerTest {
    private JamManufacturer j;

    @Before
    public void setUp() throws Exception {
        j = new JamManufacturer();
    }

    @Test
    public void test() {
        for (int jars = 0; jars < 500; jars++) {
            int nCartons = (jars + 11) / 12;
            int totalOunces = 21 * jars + 25 * nCartons;
            int lbs = (totalOunces + 15) / 16;
            double cost = 3.0 + 1.44 * nCartons + 0.96 * lbs;
            assertEquals(cost, j.computeShippingCost(jars), getTolerance(cost));
        }
    }

    /**
     *
     * @param cost
     * @return 5% tolerance for the cost
     */
    private double getTolerance(double cost) {
        return 0.05 * cost;
    }

}