@Test
public void getRootReturnsManagerWhenNodeIsNoRoot() {

    // given
    var managerNode = new HierarchyTreeNode(otherUserMock);
    var node = new HierarchyTreeNode(userMock);
    node.manager = managerNode;
    // when / then
    assertThat(node.getRoot()).isSameAs(managerNode);
}