Fix bug in Set.addAll(Collection)

Author: mikosik

src/common/src/main/java/org/smoothbuild/common/collect/Set.java

@@ -120,7 +120,7 @@ public Set<E> addAll(java.util.Collection<? extends E> collection) {
 
   public Set<E> addAll(Collection<? extends E> collection) {
     return switch (collection) {
-      case List<? extends E> l -> addAll(collection);
+      case List<? extends E> l -> addAll(l);
       case Set<? extends E> s -> addAll(s);
     };
   }

src/common/src/test/java/org/smoothbuild/common/collect/SetTest.java

@@ -368,6 +368,35 @@ void duplicates_are_removed() {
       }
     }
 
+    @Nested
+    class _custom_collection {
+      @Test
+      void two_empty_sets() {
+        assertThat(set().addAll((Collection<Object>) set())).isEqualTo(set());
+      }
+
+      @Test
+      void empty_set() {
+        assertThat(set(1).addAll((Collection<Integer>) Set.<Integer>set())).isEqualTo(set(1));
+      }
+
+      @Test
+      void to_empty_set() {
+        assertThat(set().addAll((Collection<Integer>) set(2))).isEqualTo(set(2));
+      }
+
+      @Test
+      void two_one_element_sets() {
+        assertThat(set(1).addAll((Collection<Integer>) set(2))).isEqualTo(set(1, 2));
+      }
+
+      @Test
+      void element_sets() {
+        assertThat(set(1, 2, 3).addAll((Collection<Integer>) set(4, 5, 6)))
+            .isEqualTo(set(1, 2, 3, 4, 5, 6));
+      }
+    }
+
     @Nested
     class _custom_list {
       @Test