test("object", (t) => {
    let list = new List(42, null);
    assert.strictEqual(list.first,42);
    assert.strictEqual(list.rest,null);
});

test("one node",
     (t)=>{
         let list1 = new List("hello",null)
         assert.strictEqual(list1.length(),1);
     });

test("two nodes",
     (t)=>{
         let list2 = new List ("hello", new List("world", null));
         assert.strictEqual(list2.length(),2);
     });

test("big list",
     (t)=>{
         let list3 = null;
         for (let i=0; i<100; i++){
             list3= new List (i,list3);
         }
         assert.strictEqual(list3.length(),100);
     });

test("iterator 1",
     (t)=>{
         let list2 = new List ("hello", new List("world", null));
         result="";
         for (let val of list2) {
             result+=val;
         }
         assert.strictEqual(result,"helloworld");
     });

  test("iterator 2",
     (t)=>{
         let list3 = null;
         for (let i=0; i<100; i++){
             list3= new List (i,list3);
         }
         let result = 0;
         for (let val of list3) {
             result+=val;
         }
         assert.strictEqual(result, 4950);
     });