ExampleTest.java

package com.example;

import org.junit.jupiter.api.Test;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import static org.junit.jupiter.api.Assertions.*;

class ExampleTest {

    @Test
    void testModifySmallList() {
        List<String> inputList = new ArrayList<>(Collections.nCopies(63, "Initial"));
        List<String> result = Example.modify(inputList);

        assertNull(result);
    }

    @Test
    void testModifyLargeList() {
        List<String> inputList = new ArrayList<>(Collections.nCopies(65, "Initial"));
        List<String> result = Example.modify(inputList);

        assertNotNull(result);
        assertEquals("Dieciséis", result.get(16));
        //assertEquals("Treinta y dos", result.get(32));
        assertEquals("Sesenta y cuatro", result.get(64));
    }

    /*
    @Test
    void testModifyEdgeCase() {
        List<String> inputList = new ArrayList<>(Collections.nCopies(64, "Initial"));
        List<String> result = Example.modify(inputList);

        assertNull(result);
    }
     */

}