content: import static org.assertj.core.api.Assertions.assertThat;
  
  import org.junit.jupiter.api.Disabled;
  import org.junit.jupiter.api.Test;
  
  public class TreeTest {
      @Test
      public void inorder() {
          Tree tree = new Tree(
              new Node(
                  'C',
                  new Node('B', new Node('A'), null),
                  new Node('E', new Node('D'), new Node('F'))));
  
          assertThat(tree.inorder())
              .containsExactly('A', 'B', 'C', 'D', 'E', 'F');
      }
  
      @Disabled("Remove to run test")
      @Test
      public void preorder() {
          Tree tree = new Tree(
              new Node(
                  'A',
                  new Node('B', null, new Node('C')),
                  new Node('D', new Node('E'), new Node('F'))));
  
          assertThat(tree.preorder())
              .containsExactly('A', 'B', 'C', 'D', 'E', 'F');
      }
  
      @Disabled("Remove to run test")
      @Test
      public void postorder() {
          Tree tree = new Tree(
              new Node(
                  'F',
                  new Node('B', null, new Node('A')),
                  new Node('E', new Node('C'), new Node('D'))));
  
          assertThat(tree.postorder())
              .containsExactly('A', 'B', 'C', 'D', 'E', 'F');
      }
  }
  