How to write JUnit test code in Java for the for nth Largest number function ?

package pack1;

import java.util.ArrayList;
import java.util.Arrays;

import org.junit.Assert;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;


class NthLargestJ8Junit5 {
	
	NthLargest_Using_Arrays_Generics NthLUAG;
	NthLargest_Using_ArrayList_Generic_Streams NthLUALGS;

	@BeforeEach
	void setUp() throws Exception {
		NthLUAG = new NthLargest_Using_Arrays_Generics();
		NthLUALGS= new NthLargest_Using_ArrayList_Generic_Streams();
	}

	@AfterEach
	void tearDown() throws Exception {
	}

	@Test
	@DisplayName("Positive inputs should work - Array Generics")   
	void test1() {
		Integer[] intArray = { 34, 21, 45, 75, 62, 98, 13, 49 }; 
	    Double[] doubleArray = { 34.0, 21.0, 45.0, 75.0, 62.0, 98.0, 13.0, 49.0 };
		
		Assertions.assertEquals(49, NthLUAG.nthLargest(intArray,4));
		Assertions.assertEquals(75.0, NthLUAG.nthLargest(doubleArray,2));
	}
	
	@Test
	@DisplayName("Positive inputs should work - Array List Generics Streams")   
	void test2() {
		ArrayList<String> StringSt = new ArrayList<>(
                Arrays.asList("MIKE", "RUSS", "SANJAY", "VALLI", "JOHN", "RAMAA", "DAVE", "NAGENDRA"));
	    ArrayList<Double> DoubleSt = new ArrayList<>(Arrays.asList(34.0, 21.0, 45.0, 75.0, 62.0, 98.0, 13.0, 49.0));
	  
		Assertions.assertEquals("NAGENDRA", NthLUALGS.nthLargest(StringSt,5));
		Assertions.assertEquals(62.0, NthLUALGS.nthLargest(DoubleSt,3));
	}
	
	@Test
	@DisplayName("Unavailalbe data inputs should work - Array Generics")   
	void test3() {
		Integer[] intArray = { 34, 21, 45, 75, 62, 98, 13, 49 }; 
	    Double[] doubleArray = { 34.0, 21.0, 45.0, 75.0, 62.0, 98.0, 13.0, 49.0 };
		
		Assertions.assertNotEquals(499, NthLUAG.nthLargest(intArray,4));
		Assertions.assertNotEquals(58.0, NthLUAG.nthLargest(doubleArray,2));
	}
	
	@Test
	@DisplayName("Unavailalbe data inputs should work - Array List Generics Streams")   
	void test4() {
		ArrayList<String> StringSt = new ArrayList<>(
                Arrays.asList("MIKE", "RUSS", "SANJAY", "VALLI", "JOHN", "RAMAA", "DAVE", "NAGENDRA"));
	    ArrayList<Double> DoubleSt = new ArrayList<>(Arrays.asList(34.0, 21.0, 45.0, 75.0, 62.0, 98.0, 13.0, 49.0));
	  
		Assertions.assertNotEquals("KUMAR", NthLUALGS.nthLargest(StringSt,5));
		Assertions.assertNotEquals(85.0, NthLUALGS.nthLargest(DoubleSt,3));
	}
	
	@Test
	@DisplayName("Unavailable index must throw ArrayList Generics IndexOutOfBounds Exception")   
	void test5() {
		ArrayList<Double> DoubleSt = new ArrayList<>(Arrays.asList(34.0, 21.0, 45.0, 75.0, 62.0, 98.0, 13.0, 49.0));

		Throwable exception = Assert.assertThrows(ArrayIndexOutOfBoundsException.class, () -> NthLUALGS.nthLargest(DoubleSt,18));
	   	Assertions.assertEquals("-10", exception.getMessage());
	}
	
	@Test
	@DisplayName("Unavailable index must throw Array Generics IndexOutOfBounds Exception")   
	void test6() {
		ArrayList<String> StringSt = new ArrayList<>(
                Arrays.asList("MIKE", "RUSS", "SANJAY", "VALLI", "JOHN", "RAMAA", "DAVE", "NAGENDRA"));
	 
		Throwable exception = Assert.assertThrows(ArrayIndexOutOfBoundsException.class, () -> NthLUALGS.nthLargest(StringSt,21));
	    Assert.assertEquals("-13", exception.getMessage());
	}
	
	@Test
	@DisplayName("Unavailable index must throw Array Generics IndexOutOfBounds Exception")   
	public void test7() {
		Integer[] intArray = { 34, 21, 45, 75, 62, 98, 13, 49 }; 
		
	    Throwable exception = Assert.assertThrows(ArrayIndexOutOfBoundsException.class, () -> NthLUAG.nthLargest(intArray,56));
	    Assert.assertEquals("-48", exception.getMessage());
	}
}