added test

src/main/java/mi/hdm/recipes/Categories.java

@@ -14,6 +14,8 @@ public class Categories {
         return allCategories.remove(c);
     }
 
+    public void removeCategory(String name) {}
+
     public Set<Category> getAllCategories(){
         return allCategories;
     }

src/test/java/mi/hdm/recipes/CategoryTest.java

+package mi.hdm.recipes;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class CategoryTest {
+    Categories underTest = new Categories();
+
+    @Test
+    public void testEquals() {
+        Category c1 = new Category("Abend", 0x00FF00);
+        Category c2 = new Category("LEcker", 0x13);
+        Category c3 = new Category("ew", 0x13);
+        Category c4 = new Category("ew", 0x100);
+
+        assertNotEquals(c1, c2);
+        assertEquals(c3, c4);
+        assertEquals(c2, c3);
+    }
+
+    @Test
+    public void shouldNotBeAbleToAddIdenticalName() {
+        underTest.addCategory("Mittag", 0x100000);
+        underTest.addCategory("Mittag", 0x100000);
+        Assert.assertEquals(1, underTest.getAllCategories().size());
+    }
+
+    @Test
+    public void shouldBeAbleToAddCategory() {
+        underTest.addCategory("Morgen", 0x100000);
+        Assert.assertEquals(2, underTest.getAllCategories().size());
+    }
+}