用 java这种语言以测试驱动开发实现单链表的构建、插入、删除、查找、反转。

以下是用 Java 实现单链表的代码：

public class ListNode {
    int val;
    ListNode next;
    ListNode(int x) { val = x; }
}

public class LinkedList {
    ListNode head;

    public LinkedList() {
        head = null;
    }

    // 在链表的末尾添加一个节点
    public void append(int val) {
        if (head == null) {
            head = new ListNode(val);
            return;
        }

        ListNode curr = head;
        while (curr.next != null) {
            curr = curr.next;
        }
        curr.next = new ListNode(val);
    }

    // 在链表的开头插入一个节点
    public void prepend(int val) {
        ListNode newHead = new ListNode(val);
        newHead.next = head;
        head = newHead;
    }

    // 删除链表中第一个值为 val 的节点
    public void delete(int val) {
        if (head == null) {
            return;
        }

        if (head.val == val) {
            head = head.next;
            return;
        }

        ListNode curr = head;
        while (curr.next != null && curr.next.val != val) {
            curr = curr.next;
        }
        if (curr.next != null) {
            curr.next = curr.next.next;
        }
    }

    // 查找链表中是否存在值为 val 的节点
    public boolean search(int val) {
        ListNode curr = head;
        while (curr != null) {
            if (curr.val == val) {
                return true;
            }
            curr = curr.next;
        }
        return false;
    }

    // 反转整个链表
    public void reverse() {
        ListNode prev = null;
        ListNode curr = head;
        while (curr != null) {
            ListNode next = curr.next;
            curr.next = prev;
            prev = curr;
            curr = next;
        }
        head = prev;
    }
}

下面是使用 JUnit 进行测试的代码：

import org.junit.Test;
import static org.junit.Assert.*;

public class LinkedListTest {
    @Test
    public void testAppend() {
        LinkedList list = new LinkedList();
        list.append(1);
        list.append(2);
        list.append(3);
        assertEquals(1, list.head.val);
        assertEquals(2, list.head.next.val);
        assertEquals(3, list.head.next.next.val);
    }

    @Test
    public void testPrepend() {
        LinkedList list = new LinkedList();
        list.prepend(1);
        list.prepend(2);
        list.prepend(3);
        assertEquals(3, list.head.val);
        assertEquals(2, list.head.next.val);
        assertEquals(1, list.head.next.next.val);
    }

    @Test
    public void testDelete() {
        LinkedList list = new LinkedList();
        list.append(1);
        list.append(2);
        list.append(3);
        list.delete(2);
        assertEquals(1, list.head.val);
        assertEquals(3, list.head.next.val);
        assertFalse(list.search(2));
    }

    @Test
    public void testSearch() {
        LinkedList list = new LinkedList();
        list.append(1);
        list.append(2);
        list.append(3);
        assertTrue(list.search(2));
        assertFalse(list.search(4));
    }

    @Test
    public void testReverse() {
        LinkedList list = new LinkedList();
        list.append(1);
        list.append(2);
        list.append(3);
        list.reverse();
        assertEquals(3, list.head.val);
        assertEquals(2, list.head.next.val);
        assertEquals(1, list.head.next.next.val);
    }
}

以上代码实现了单链表的构建、插入、删除、查找和反转，并使用测试驱动开发的方式进行了测试，确保代码的正确性。