JUnit 5 Tutorial

In this tutorial, you will learn how to write a JUnit test to use the assertTimeout() static method with examples.

The assertTimeout() method asserts that execution of the supplied supplier completes before the given timeout is exceeded.

Let's first create Book, BookService classes, and then we will write JUnit test cases to use the assertTimeout() static method.

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 assertTimeout() method

The below Java program demonstrates the usage of all overloaded assertTimeout() static method with a message:

package junit5.assertions.assertTimeout;

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

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 AssertTimeoutDemo {

	@Test
	public void assertTimeoutWithNoMessage() {
		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<>();
		
		assertTimeout(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		});
		
		assertEquals(1000, actualTitles.size());
		
	}
	
	@Test
	public void assertTimeoutWithMessage() {
		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<>();
		
		assertTimeout(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		}, "Performance issues with getBookTitlesByPublisher() method !");
		
		assertEquals(1000, actualTitles.size());
		
	}
	
	@Test
	public void assertTimeoutWithMessageSupplier() {
		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<>();
		
		assertTimeout(Duration.ofMillis(1), () -> {
			actualTitles.addAll(bookService.getBookTitlesByPublisher("Wrox"));
		}, () -> "Performance issues with getBookTitlesByPublisher() method !");
		
		assertEquals(1000, actualTitles.size());
	}
}