Kumite

class Node {
    constructor(val) {
        this.data = val;
        this.left = null;
        this.right = null;
    }
}

const chai = require("chai");
const assert = chai.assert
 a = new Node("A")
var b = new Node("B");
var c = new Node("C");
var d = new Node("D");
var e = new Node("E");
var f = new Node("F");
var g = new Node("G");

a.left = b;
a.right = c;
b.left = d;
b.right = e;
c.left = f;
c.right = g;

;
chai.config.truncateThreshold = 0;

describe("treeHeight", function() {
  it("given null", function() {
    assert.equal(treeHeight(null), 0);
  });  
  it("given a", function() {
    assert.equal(treeHeight(a), 3);
  });
  it("given b", function() {
    assert.equal(treeHeight(b), 2);
  });
  it("given c", function() {
    assert.equal(treeHeight(c), 2);
  });
  it("given d", function() {
    assert.equal(treeHeight(d), 1);
  });
  it("given e", function() {
    assert.equal(treeHeight(e), 1);
  });
  it("given f", function() {
    assert.equal(treeHeight(f), 1);
  });
  it("given g", function() {
    assert.equal(treeHeight(g), 1);
  });
  // TODO: non-existing value
});