unit test failing in java and not sure why

Question

I have a method in class TreeUtils that checks for simalarity of structure between two binary search trees

if(root1 == null&& root2 == null)
    {
        return true;
    }
    if(root1 == null && root2!=null){
        return false;
    }
    if(root1 != null && root2 == null)
    {
        return false;
    }

    boolean leftRecurse = similar(root1.getLeft(), root2.getLeft());
    boolean rightRecurse = similar(root1.getRight(), root2.getRight());

    return leftRecurse && rightRecurse;

however when I run a unit test on this file it fails. But if I call this method from the main method, it works. Its not a package or scope issue, because the similar method works in the main method. I think it has something to do with

 public BinaryTreeNode getLeft() { 
    assert(this.hasLeft());
    return this.left; 
}

maybe because this is now a unit test it is calling the assert? how should I modify my similar method to avoid this.

This is my Unit test

public void testSimilar() {
    System.out.println("Test similarity");
    SimpleBST tree = new SimpleBST();
    tree.insert(1);
    tree.insert(2);
    SimpleBST tree2 = new SimpleBST();
    tree2.insert(1);
    tree2.insert(3);
    assertEquals(true, tree.similar(tree2));


}

thanks.

Answer 1

Assuming you have asserts enabled with -ea argument the program will throw an AssertionError if this does not have a left child. But by the setup you have, recursively you want to evaluate the left and right child even if they are null. Simply removing the assertion will work.