Add supercategory and subcategories to Category.class

src/main/java/de/unipotsdam/cs/toolup/model/Category.java

@@ -8,9 +8,13 @@ import static de.unipotsdam.cs.toolup.database.DatabaseController.TABLE_NAME_APP
 
 public class Category extends BusinessObject {
 
+    private String superCategory;
+    private Collection<String> subCategories;
+
     public Category(String uuid, String title, String description, Set<String> relatedApplications) {
         super(uuid, title, description);
         this.relations.put(TABLE_NAME_APPLICATION, relatedApplications);
+        this.subCategories = new HashSet<>();
     }
 
     public Category(String uuid) {
@@ -20,4 +24,20 @@ public class Category extends BusinessObject {
     public Collection<String> getRelatedApplications() {
         return new HashSet<>(this.relations.get(TABLE_NAME_APPLICATION));
     }
+
+    public String getSuperCategory() {
+        return superCategory;
+    }
+
+    public void setSuperCategory(String superCategory) {
+        this.superCategory = superCategory;
+    }
+
+    public Collection<String> getSubCategories() {
+        return new HashSet<>(subCategories);
+    }
+
+    public void addSubCategories(Collection<String> subcategories) {
+        this.subCategories.addAll(subcategories);
+    }
 }

src/test/java/de/unipotsdam/cs/toolup/model/CategoryTest.java

+package de.unipotsdam.cs.toolup.model;
+
+import org.testng.annotations.Test;
+
+import java.util.Arrays;
+import java.util.Collection;
+
+import static de.unipotsdam.cs.toolup.util.AssertionUtil.assertCollectionEquals;
+import static org.testng.Assert.assertEquals;
+
+public class CategoryTest extends BusinessObjectTest {
+
+    @Test
+    public void testThatCategoryMayHaveSuperCategory() {
+        //arrange
+        Category cat = new Category(CATEGORY_TEST_ID_11, null, null, null);
+        String superCategoryId = CATEGORY_TEST_ID_13;
+
+        //act
+        cat.setSuperCategory(superCategoryId);
+
+        //assert
+        assertEquals(superCategoryId, cat.getSuperCategory());
+    }
+
+    @Test
+    public void testThatCategoryMayHaveSubCategories() {
+        //arrange
+        Category cat = new Category(CATEGORY_TEST_ID_13, null, null, null);
+        Collection<String> subcategories = Arrays.asList(CATEGORY_TEST_ID_11, CATEGORY_TEST_ID_12);
+
+        //act
+        cat.addSubCategories(subcategories);
+
+        //assert
+        assertCollectionEquals(subcategories, cat.getSubCategories());
+    }
+
+}