Solve d.

Java/src/main/java/org/codecop/dependencies/d/ShippingCost.java

@@ -5,11 +5,11 @@ public class ShippingCost {
     public Money calculate(Country country, DeliveryOptions options) {
         final Money cost;
 
-        if (RestCountriesAPI.getInstance().isInCommonMarket(country)) {
+        if (getRestCountriesApi().isInCommonMarket(country)) {
             // flat rate in EU
             cost = new Money(5);
 
-        } else if (RestCountriesAPI.getInstance().isInAmericas(country)) {
+        } else if (getRestCountriesApi().isInAmericas(country)) {
             // US & Canada & South American
             if (options == DeliveryOptions.EXPRESS) {
                 cost = new Money(40);
@@ -19,11 +19,15 @@ public Money calculate(Country country, DeliveryOptions options) {
 
         } else {
             // other countries, e.g. Asia
-            int km = RestCountriesAPI.getInstance().distanceTo(country);
+            int km = getRestCountriesApi().distanceTo(country);
             cost = new Money(km).percentage(10);
         }
 
         return cost;
     }
 
+    protected RestCountriesAPI getRestCountriesApi() {
+        return RestCountriesAPI.getInstance();
+    }
+
 }

Java/src/test/java/org/codecop/dependencies/d/ShippingCostTest.java

@@ -1,15 +1,27 @@
 package org.codecop.dependencies.d;
 
-import org.junit.Test;
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
 
-import static org.junit.Assert.assertNotNull;
+import org.junit.Test;
 
 public class ShippingCostTest {
 
     @Test
     public void test4() {
-        ShippingCost shippingCost = new ShippingCost();
-
-        assertNotNull(shippingCost);
+        RestCountriesAPI restCountriesAPI = mock(RestCountriesAPI.class);
+        when(restCountriesAPI.isInCommonMarket(new Country("AT"))).thenReturn(true);
+        ShippingCost shippingCost = new ShippingCost() {
+          @Override
+            protected RestCountriesAPI getRestCountriesApi() {
+                return restCountriesAPI;
+            }  
+        };
+
+        Money cost = shippingCost.calculate(new Country("AT"), DeliveryOptions.STANDARD);
+
+        assertEquals(new Money(5), cost);
+        // 3 seconds
     }
 }