Testing Your Linked List

Now that we have implemented all the core functionalities of our LinkedList, let’s write a main() method that will test every function.

If the code runs without any errors, it means you implemented your Linked List correctly!

Test Code:

#include <iostream>
#include <cassert>  // For assert()
#include "LinkedList.h"

int main() {
    LinkedList list;

    // Step 1: Test empty list
    assert(list.is_empty());  // Expected: true
    assert(list.size() == 0); // Expected: 0
    std::cout << "Initial list is empty" << std::endl;

    // Step 2: Test push_front and push_back
    list.push_front(10);
    list.push_front(20);
    list.push_front(30); // List: 30 → 20 → 10
    list.push_back(5);
    list.push_back(40);
    list.push_back(50);  // List: 30 → 20 → 10 → 5 → 40 → 50
    assert(list.size() == 6); // Expected: 6
    std::cout << "Insertion tests passed" << std::endl;

    // Step 3: Test get_node_at
    assert(list.get_node_at(0)->data == 30);
    assert(list.get_node_at(2)->data == 10);
    assert(list.get_node_at(4)->data == 40);
    assert(list.get_node_at(6) == nullptr); // Out-of-bounds test
    std::cout << "get_node_at tests passed" << std::endl;

    // Step 4: Test get_node_by_value
    assert(list.get_node_by_value(20) != nullptr);
    assert(list.get_node_by_value(100) == nullptr); // Value does not exist
    std::cout << "get_node_by_value tests passed" << std::endl;

    // Step 5: Test push_at_n
    assert(list.push_at_n(25, 3)); // Insert at index 3
    assert(list.size() == 7);
    assert(list.get_node_at(3)->data == 25);
    std::cout << "push_at_n tests passed" << std::endl;

    // Step 6: Test remove_at_n
    assert(list.remove_at_n(4)); // Remove index 4
    assert(list.size() == 6);
    assert(list.get_node_at(4)->data == 40); // 5 was removed
    std::cout << "remove_at_n tests passed" << std::endl;

    // Step 7: Test invalid remove
    assert(!list.remove_at_n(10)); // Out-of-bounds removal
    std::cout << "Invalid removal test passed" << std::endl;

    // Step 8: Test final list state
    list.print_list();  // Should print: 30 → 20 → 10 → 25 → 50 → NULL
    assert(list.size() == 6);
    std::cout << "Final list state test passed" << std::endl;

    std::cout << "\nAll tests passed successfully!" << std::endl;
    return 0;
}