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Testing Sorted List Merge Algorithm in JCSprout

This test suite validates the functionality of merging two sorted linked lists in the JCSprout project. It provides comprehensive test coverage for the MergeTwoSortedLists class implementation, including scenarios with null inputs and varying list lengths.

Test Coverage Overview

The test suite covers multiple scenarios for merging sorted linked lists:

Merging two non-empty sorted lists of different lengths
Merging a null list with a non-empty list
Merging a non-empty list with a null list
Verification of proper sorting and node connections

Implementation Analysis

The testing approach utilizes JUnit’s structured testing framework with @Before and @Test annotations. Each test case constructs linked lists programmatically, executes the merge operation, and validates results using Assert statements for precise output verification.

The implementation demonstrates proper test isolation and setup patterns with separate test methods for different scenarios.

Technical Details

Testing tools and configuration:

JUnit 4 testing framework
Custom ListNode class implementation
Before setup method for test initialization
Assert.assertEquals for result validation
toString() method utilization for node comparison

Best Practices Demonstrated

The test suite exhibits several testing best practices:

Proper test method naming and organization
Comprehensive edge case coverage
Clear test setup and teardown structure
Effective use of JUnit lifecycle methods
Robust assertion checking for validation

crossoverjie/jcsprout

src/test/java/com/crossoverjie/algorithm/MergeTwoSortedListsTest.java

            
package com.crossoverjie.algorithm;

import com.crossoverjie.algorithm.MergeTwoSortedLists.ListNode;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;

public class MergeTwoSortedListsTest {
    MergeTwoSortedLists mergeTwoSortedLists ;
    @Before
    public void setUp() throws Exception {
        mergeTwoSortedLists = new MergeTwoSortedLists();
    }

    @Test
    public void mergeTwoLists() throws Exception {
        ListNode l1 = new ListNode(1) ;
        ListNode l1_2 = new ListNode(4);
        l1.next = l1_2 ;
        ListNode l1_3 = new ListNode(5) ;
        l1_2.next = l1_3 ;

        ListNode l2 = new ListNode(1) ;
        ListNode l2_2 = new ListNode(3) ;
        l2.next = l2_2 ;
        ListNode l2_3 = new ListNode(6) ;
        l2_2.next = l2_3 ;
        ListNode l2_4 = new ListNode(9) ;
        l2_3.next = l2_4 ;
        ListNode listNode = mergeTwoSortedLists.mergeTwoLists(l1, l2);


        ListNode node1 = new ListNode(1) ;
        ListNode node2 = new ListNode(1);
        node1.next = node2;
        ListNode node3 = new ListNode(3) ;
        node2.next= node3 ;
        ListNode node4 = new ListNode(4) ;
        node3.next = node4 ;
        ListNode node5 = new ListNode(5) ;
        node4.next = node5 ;
        ListNode node6 = new ListNode(6) ;
        node5.next = node6 ;
        ListNode node7 = new ListNode(9) ;
        node6.next = node7 ;
        Assert.assertEquals(node1.toString(),listNode.toString());


    }

    @Test
    public void mergeTwoLists2() throws Exception {

        ListNode l2 = new ListNode(1) ;
        ListNode l2_2 = new ListNode(3) ;
        l2.next = l2_2 ;
        ListNode l2_3 = new ListNode(6) ;
        l2_2.next = l2_3 ;
        ListNode l2_4 = new ListNode(9) ;
        l2_3.next = l2_4 ;
        ListNode listNode = mergeTwoSortedLists.mergeTwoLists(null, l2);

        System.out.println(listNode.toString());


    }

    @Test
    public void mergeTwoLists3() throws Exception {

        ListNode l2 = new ListNode(1) ;
        ListNode l2_2 = new ListNode(3) ;
        l2.next = l2_2 ;
        ListNode l2_3 = new ListNode(6) ;
        l2_2.next = l2_3 ;
        ListNode l2_4 = new ListNode(9) ;
        l2_3.next = l2_4 ;
        ListNode listNode = mergeTwoSortedLists.mergeTwoLists(l2, null);


        ListNode node1 = new ListNode(1) ;
        ListNode node2 = new ListNode(3);
        node1.next = node2;
        ListNode node3 = new ListNode(6) ;
        node2.next= node3 ;
        ListNode node4 = new ListNode(9) ;
        node3.next = node4 ;

        Assert.assertEquals(node1.toString(),listNode.toString());

    }

}