JUnit assertTimeoutPreemptively Example

In this tutorial, we will learn how to write a JUnit test case to use the assertTimeoutPreemptively() static method with an example.

Let's first create Book, BookService classes, and then we will write JUnit test cases to use assertTimeoutPreemptively() methods.

Create Book Class

package junit5.bookstore.model;

public class Book {
	
	private String bookId;
	private String title;
	private String publisher;
	
	public Book(String bookId, String title, String publisher) {
		this.bookId = bookId;
		this.title = title;
		this.publisher = publisher;
	}

	public String getBookId() {
		return bookId;
	}

	public void setBookId(String bookId) {
		this.bookId = bookId;
	}

	public String getTitle() {
		return title;
	}

	public void setTitle(String title) {
		this.title = title;
	}

	public String getPublisher() {
		return publisher;
	}

	public void setPublisher(String publisher) {
		this.publisher = publisher;
	}
	
}

Create BookService Class

package junit5.bookstore.service;

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

import junit5.bookstore.model.Book;

public class BookService {
	
	private List<Book> listOfBooks = new ArrayList<>();
	
	public void addBook(Book book) {
		listOfBooks.add(book);
	}	
	
	public List<Book> books(){
		return Collections.unmodifiableList(listOfBooks);
	}
	
	public Book getBookById(String bookId) {
		for(Book book : listOfBooks) {
			if(bookId.equals(book.getBookId())) {
				return book;
			}
		}
		return null;
	}
	
	public String[] getBookIdsByPublisher(String publisher) {
		List<String> bookIds = new ArrayList<>();
		for(Book book : listOfBooks) {
			if(publisher.equals(book.getPublisher())) {
				bookIds.add(book.getBookId());
			}
		}
		return bookIds.toArray(new String[bookIds.size()]);
	}
	
	public List<String> getBookTitlesByPublisher(String publisher) {
		List<String> bookTitles = new ArrayList<>();
		for(Book book : listOfBooks) {
			if(publisher.equals(book.getPublisher())) {
				bookTitles.add(book.getTitle());
			}
		}
		return bookTitles;
	}
}

Write JUnit test to use assertTimeoutPreemptively() method

The below Java program demonstrates the usage of all overloaded assertTimeoutPreemptively() static methods:

package junit5.assertions.assertTimeoutPreemptively;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTimeout;
import static org.junit.jupiter.api.Assertions.assertTimeoutPreemptively;

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;

import org.junit.jupiter.api.Test;

import junit5.bookstore.model.Book;
import junit5.bookstore.service.BookService;

public class AssertTimeoutPreemptivelyDemo {

	@Test
	public void assertTimeoutPreemptivelyWithNoMessage() {
		BookService bookService = new BookService();
		
		for(int i = 1; i <= 1000; i++) {
			bookService.addBook(new Book(String.valueOf(i), "Head First Java", "Wrox"));
		}
		
		List<String> actualTitles = new ArrayList<>();
		
		assertTimeoutPreemptively(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		});
		
		assertEquals(1000, actualTitles.size());
		
	}
	
	@Test
	public void assertTimeoutPreemptivelyWithMessage() {
		BookService bookService = new BookService();
		
		for(int i = 1; i <= 1000; i++) {
			bookService.addBook(new Book(String.valueOf(i), "Head First Java", "Wrox"));
		}
		
		List<String> actualTitles = new ArrayList<>();
		
		assertTimeoutPreemptively(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		}, "Performance issues with getBookTitlesByPublisher() method !");
		
		assertEquals(1000, actualTitles.size());
		
	}
	
	@Test
	public void assertTimeoutPreemptivelyWithMessageSupplier() {
		BookService bookService = new BookService();
		
		for(int i = 1; i <= 1000; i++) {
			bookService.addBook(new Book(String.valueOf(i), "Head First Java", "Wrox"));
		}
		
		List<String> actualTitles = new ArrayList<>();
		
		assertTimeoutPreemptively(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		}, () -> "Performance issues with getBookTitlesByPublisher() method !");
		
		assertEquals(1000, actualTitles.size());
		
	}
	
}

Run JUnit test Class

Run the JUnit test class to execute all the JUnit test cases and here is the output:

Reference

JUnit 5 Assertions Java Doc

Related JUnit 5 Examples

• JUnit 5 assertAll Example

• JUnit 5 assertArrayEquals Example

• JUnit 5 assertEquals Example

• JUnit 5 assertNotEquals Example

• JUnit 5 assertNotSame Example

• JUnit 5 assertNull and assertNotNull Example

• JUnit 5 assertSame Example

• JUnit 5 assertThrows Example

• JUnit 5 assertTimeout Example

• JUnit 5 assertFalse Example

• JUnit 5 assertTrue Example