@Test
public void test_toString_on_an_emptyStack() {

    Assert.assertEquals("Empty Stack", stk1.toString());

}

@Test
public void test_toString_on_a_stack_with_1_element() {

    stk1.push(5);

    Assert.assertEquals("bottom|5|top", stk1.toString());
}

@Test
public void test_toString_on_a_stack_with_multiple_elements() {

    stk1.push(5); stk1.push(4); stk1.push(3);

    Assert.assertEquals("bottom|5|4|3|top", stk1.toString());
}

@Test
public void test_toString_on_a_full_stack() {

    stk1.push(1); stk1.push(2); stk1.push(3); stk1.push(4); stk1.push(5);

    Assert.assertEquals("bottom|1|2|3|4|5|top", stk1.toString());
}

@Test
public void test_toString_on_a_string_store_stack()
{

}