Reward value

src/main/java/RewardValue.java

@@ -0,0 +1,31 @@
+public class RewardValue {
+    private Double cash = null;
+    private Integer miles = null;
+    public static final double MILES_TO_CASH = 0.0035;
+
+    public RewardValue(double cashValue) {
+        if (cashValue >= 0)
+            cash = cashValue;
+        else
+            throw new IllegalArgumentException("cash value must be positive");
+    }
+
+    public RewardValue(int milesValue) {
+        if (milesValue >= 0)
+            miles = milesValue;
+        else
+            throw new IllegalArgumentException("miles value must be positive");
+    }
+
+    public double getCashValue() {
+        if (cash != null)
+            return cash;
+        return MILES_TO_CASH * miles;
+    }
+
+    public int getMilesValue() {
+        if (miles != null)
+            return miles;
+        return (int) (1 / MILES_TO_CASH * cash);
+    }
+}

src/test/java/RewardValueTests.java

@@ -3,6 +3,7 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 public class RewardValueTests {
+    public static final double MILES_TO_CASH = 0.0035;
 
     @Test
     void create_with_cash_value() {
@@ -20,11 +21,17 @@ void create_with_miles_value() {
 
     @Test
     void convert_from_cash_to_miles() {
-        assert false;
+        double cashValue = 100;
+        var rewardValue = new RewardValue(cashValue);
+        int milesValue = rewardValue.getMilesValue();
+        assertEquals(milesValue, (int) (cashValue / MILES_TO_CASH));
     }
 
     @Test
     void convert_from_miles_to_cash() {
-        assert false;
+        int milesValue = 1000;
+        var rewardValue = new RewardValue(milesValue);
+        double cashValue = rewardValue.getCashValue();
+        assertEquals(cashValue, milesValue * MILES_TO_CASH);
     }
 }