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Vinod is Sun Certified and love to work in Java and related technologies. Having more than 13 years of experience, he had developed software's including technologies like Java, Hibernate, Struts, Spring, HTML 5, jQuery, CSS, Web Services, MongoDB, AngularJS, AWS. He is also a JUG Leader of Chandigarh Java User Group.

Junit Test Timeout Example

In this article, we shall show you the working of JUnit timeout. JUnit provides a very good way of testing your methods against the timeout. In JUnit Test Timeout example, we will show how we can test out methods for timeouts.

There are times when we want our methods to execute in a specific time. For example, we want a method to be completed in 1 second. This can be achieved easily by using different types in JUnit.

1. Introduction

As a regular reader, you already know that JUnit is a powerful way of unit testing our programs. It provides various techniques through which we can test our methods.

Let’s take a case where our method is taking a lot of time to execute. It causes a lot of performance issue and you want to test in a way so that it completes in a specific time. What will you do?

To answer this, JUnit provides a way through which this can be achieved. We will see in this example how we can do that.

2. Ways to Test Timeout

So, JUnit provides 3 different ways of testing methods against the time.

We will see these 3 methods in details in below example.

3. Project Setup

Tip
You may skip project creation and jump directly to the beginning of the example below.

We are using Eclipse for this project. We are also using Maven as a dependency build tool. Open Eclipse, Click File -> New -> Maven Project.
Fill in the details as shown and click Next button.

JUnit Test Timeout Example Setup 1

Figure 1: JUnit Test Timeout Example Setup 1

Fill all details as shown and click on Finish button.

JUnit Test Timeout Example Setup 2

Figure 2: JUnit Test Timeout Example Setup 2

We are done with the project setup.

4. JUnit Test Timeout Example

First of all copy below code and paste in your pom.xml.

pom.xml

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

    <properties>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

Now we create a simple bean class for testing.

Bank.java

package junittesttimeout;

import java.util.concurrent.TimeUnit;

public class Bank {

	private double totalCash;
	private int totalAccounts;

	public Bank(double cash, int accounts) {
		this.totalCash = cash;
		this.totalAccounts = accounts;
	}

	public double getTotalCash() throws InterruptedException {
		double cash = 0.0;
		for (int index = 0; index < 5; index++) {
			cash += index;
			TimeUnit.SECONDS.sleep(1);
		}
		return cash;
	}

	public int getTotalAccounts() throws InterruptedException {
		TimeUnit.MILLISECONDS.sleep(500);
		return totalAccounts;
	}

	@Override
	public String toString() {
		return "Bank [cash=" + totalCash + ", accounts=" + totalAccounts + "]";
	}
}

This class is used for testing purpose only. As you can see, we are having time sleep statements(highlighted) in the program. That are used for testing timeout scenarios.

5. Test Class

Let’s explore the various strategies.

5.1 Using timeout parameter

We can use timeout parameter with @Test

TestClass.java

package junittesttimeout;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import org.junit.BeforeClass;
import org.junit.Test;

public class TestTimeout {

	private static Bank bank;

	@BeforeClass
	public static void init() {
		bank = new Bank(500000, 100);
	}

	@Test(timeout = 2000)
	public void totalCashTest() throws InterruptedException {
		assertThat(10.0, is(bank.getTotalCash()));
	}
	
	@Test(timeout = 1000)
	public void totalAccountsTest() throws InterruptedException {
		assertThat(100, is(bank.getTotalAccounts()));
	}
}

In this example, at line 18 and 23, we have set the timeout on tests. Now when the method starts execution and it takes more time than the timeout specified it will not pass and eventually fail. If test the case executes within a specified time then it will pass.

5.2 Using @Rule annotation

We can use @Rule annotation. This is helpful when we want all our test cases to be passed within a specific time. For example, we want our each test case to be executed in 2 seconds. See example below for more details.

TestTimeoutGlobal.java

package junittesttimeout;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import org.junit.BeforeClass;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.Timeout;

public class TestTimeoutGlobal {

	private static Bank bank;
	
	@Rule
    public Timeout globalTimeout = Timeout.seconds(2);

	@BeforeClass
	public static void init() {
		bank = new Bank(500000,100);
	}

	@Test
	public void totalCashTest() throws InterruptedException {
		assertThat(10.0, is(bank.getTotalCash()));
	}
	
	@Test
	public void totalAccountsTest() throws InterruptedException {
		assertThat(100, is(bank.getTotalAccounts()));
	}
}    

Here we simply, create @Rule at starting of the class. It applies to each and every test case in a class including @BeforeClass and @Before annotations.

5.3 Using @ClassRule annotation

We can use the @ClassRule annotation on class. It will see that all methods in a class execute in a specific time. So, here we want all the test cases collectively to be passed within a specific time of 10 seconds.

TestTimeoutGlobalClass.java

package junittesttimeout;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import org.junit.BeforeClass;
import org.junit.ClassRule;
import org.junit.Test;
import org.junit.rules.Timeout;

public class TestTimeoutGlobalClass {

	private static Bank bank;

	@ClassRule
	public static Timeout globalTimeout = Timeout.seconds(10);

	@BeforeClass
	public static void init() {
		bank = new Bank(500000, 100);
	}

	@Test
	public void totalCashTest() throws InterruptedException {
		assertThat(10.0, is(bank.getTotalCash()));
	}

	@Test
	public void totalAccountsTest() throws InterruptedException {
		assertThat(100, is(bank.getTotalAccounts()));
	}
}
Tip
Difference between @Rule and @ClassRule is that, former is used for testing each method for a specific time, whereas latter is used to test all methods to be executed in a specific time.

Above example will simply executes the methods of the class and sees that all test cases passed in a specific time of i.e. 10 seconds.

6. Conclusion

Through this example, you have learned how we can test our methods against time. We have used 3 strategies for this.

  1. using timeout parameter with @Test
  2. using @Rule annotation
  3. using @ClassRule annotation

7. Download the Eclipse Project

This is an example of JUnit Test Timeout.

Download
You can download the full source code of this example here: JUnitTestTimeoutExample.zip
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