In this tutorial, we will learn how to test Java Applications. You will see the components involved in a Java application and the types of testing that need to be carried out to ensure a high-quality, bug-free application.

We have created a three-part series on testing JAVA applications:

1. In this article, we will learn the J2EE components and Manual testing approach for a J2EE application.
2. Second, we will review the Automated testing approach for testing J2EE applications, and
3. Lastly, we will review a comprehensive list of tools that are available for testing in J2EE applications.

Let’s Start With an Overview of J2EE Applications

A Java web application consists of several components, each serving an important purpose. MVC, which stands for Model View Controller, stands as the most popular and frequently used architectural design pattern.

Before learning how to test, let us briefly go through the various components of a J2EE application.

• Client/Browser is asking for a web address with a URL.
• JSP (Java Server Pages) – JSP is a server-side technology intended to present data to the user. It supports the display of dynamic content with the help of special tags called JSP tags, which help insert Java code within HTML pages. [Static HTML always displays the same content]. At runtime, a JSP is converted to a Servlet. Business logic is not typically written here.
• JSF (Java Server Faces) – JSF is a view component framework for the effective design of the User Interface.
• Javascript/Jquery – are scripting languages used for Client side validation of the View/screen.
• Servlet – A Servlet validates the data received from the input, selects the appropriate business logic code, and passes on the values to the Bean code.
• Enterprise Java Bean (EJB) – This is where the entire business logic is typically written and handled. Bean then calls for the code to either read, write or update the database. Once the database operations are complete, the response is then transferred back to the Servlet, which in turn selects the appropriate JSP to display the results.
• WebServices – Webservices are components of an application which runs on a separate server and communicates over HTTP protocol.
• Database – stores the entire data of the application.

Please note that not all web applications follow the JSP -> Servlet -> EJB -> Database model. Most of the J2EE applications are currently written with a framework such as Struts, Spring, or Hibernate. The design of applications varies for each requirement based on the size of the application, cost, development time, resources and team size.

Testing JAVA/J2EE Application

Let us now move to testing an entire J2EE application. This is done in several steps. For example, consider that we have three screens:

• The login screen
• An employee display screen, which lists all employees in the organization
• Employee modification/addition/removal screen.

The UI (User Interface) for these three screens is developed with JSP/HTML and the validations are performed through JavaScript. Since it is a sample application, the logic is in the Servlet and DAO (Data Access Object). DAO is a class for connecting to the database.

The sample screens are given below:

Manual Java Application Testing

During manual JAVA testing, a tester prepares the test cases from the detailed design document and tries to cover every scenario and code snippet possible.

#1) JAVA UNIT TESTING

Unit testing is a type of testing wherein a user needs to test the smallest of the code snippets for accuracy, correctness and meeting the requirements.

Let us give an example of the login screen. The login screen has two text fields: username and password, and has two buttons: submit and cancel.

Test cases should cover all loops and conditional statements. Test cases should display the expected results and test data. Below are some of the general test cases that a user can execute manually on the login screen. The results are then noted down in the test case document.

Below is a sample test case format for the login screen.

While the table lists some of the test cases, given below is the complete list:

• Check for any exceptions, including NULL pointer exceptions
• Check if NULLS is not allowing for username and password
• Check if the username/password is in the correct format
• Check if numbers are not allowed for username
• Check if special characters are not allowed in Username
• Check if the correct combination of Username and password is entered, then the application takes you to the next screen, i.e. Employee Information Screen
• Check if the username entered is of the correct length
• Check if the username text field allows only the maximum number of characters specified for that field
• Check if the password field if specified in the requirements is visible as * while entering
• Check if passwords are case sensitive
• Check if the username is not case sensitive
• Check if the login page does not remember the username or password, even after exiting
• Check if the Submit and Cancel button works as per requirement
• If using the application for the first time, check if the username has permission to enter the application
• Delete the username/password combination from the database and check if the combination is unable to login again
• For all the above cases, check if the appropriate validation error messages are shown
• Check if the Labels and Buttons are in the right place on the screen and that they display the text correctly
• Check if the screen appearances are as per requirements
• Check if exceptions are handled
• Check if logging is performed for required actions

After going through the test cases, you may realize that you are mostly dealing with the testing of fields, buttons, functionality, and validations of a particular screen. This is accurate as Unit Testing very keenly deals with the testing of every small code snippet and component. The same type of testing should be performed for all the screens.

Please note that the above are examples only, and test cases are prepared based on a project-specific and detailed design document.

Read Also => Sample ready to use test cases and test scenarios for web application testing.

#2) INTEGRATION TESTING

For Integration testing, individual modules are integrated and tested together for correctness.

Let each of the three screens in the above example be developed by three different team members. Now that they are finished with Unit testing, it is time to bring all the code together and check if they work well together. Integration testing is performed to ensure that data or control is transferred correctly from one screen to another.

Here are some sample integration test cases for the Employee Application example:

• Check if the user is logged in and the session is the same on all the other new integrated screens.
• Check if the other modules are not updating/deleting/inserting any records in the database unrequired.
• Let there be an employee status field, which says ‘New’ on addition,’Updated’ on modification, and “Deleted” on deletion. Although two or three screens can use the same status field, it is important to ensure the field is not being wrongly updated.
• Check if the header, footer, screen size and appearance meet the requirements after integration.
• Check that when clicking on the Submit button, the controls are transferred to the next screen.
• Check that when clicking on the Cancel button, the action performed is cancelled.

In addition, the general integration test cases for a J2EE application could be:

• Check the flow of data, either Object, XML or Session from end to end. Check for correctness.
• Check whether the session is managed correctly by each of the modules.
• If external applications (web services) are involved, check whether your application is able to make calls and retrieve data back from the application.

#3) SYSTEM TESTING

During System testing, the entire application is tested for functionality and completeness with respect to the requirements. It would likely be easier to ask when Unit testing of each component is performed and the code components are combined and tested together during integration testing, what could be different in System testing? It is not inaccurate to say that the idea in System Testing is to break the application 🙂

Scenario #1: You develop a new employee application with a framework; for example, Struts. There are also several other applications running on different servers in your organization. However, all of them call the same existing web service to fetch the address and phone number for any particular person.

During integration testing, you would have tested if your application is able to make calls to the web service and if you are able to get a response. But what if there is a problem with the web service itself? Or does the web service not respond to some rare inputs? The web service, in our case, can only take an employee number max of 6 characters. Or, the web service throws exceptions for certain formats of address while returning. This is external, but it is also part of System testing.

Scenario #2: Your employee application is complete. When you add an employee, it generates an Employee Number #1001. You modify, delete, update, add, modify, delete, add, add, add, modify, delete and then finally add another. What if the new employee number is again #1001?

Scenario #3: Let us assume that two users are using the application at the same time. Both of them start working on the same employee, one deletes. What if the other user is able to proceed with the modification of the same employee as it is stored in the session?

Given Below are some important aspects of system testing:

• Ensure the flow of data and control is correct from end-to-end.
• Ensure security of the transaction data.
• Ensure the application follows all business functionalities.
• Check if the application works well as an end product – check broken links, session management, cookies, logging, error handling, exception handling, validation, and transaction flow.

#4) PERFORMANCE TESTING

This type of testing is performed when there would be a large number of users using the application or large amount of data in the database, or both. Some of the cases are given below:

• If multiple users login at the same time, then check that the applications do not hang/crash
• If a large amount of data is available in the database – check that the search screen grids do not take very long to execute queries before session timeout.
• In a multi-threaded environment, check that the application is able to handle all threads well
• In applications where large numbers of objects are created, check whether sufficient memory is allocated, garbage collection is handled, and that there are no out of memory exceptions.

Conclusion

In this article, we have covered an overview of a J2EE application. We have also looked at how to manually perform Unit, Integration, Functional and System testing for each of the components of the application with an example.

In the next article, we will see how Automation testing can be beneficial for large J2EE applications.

About Author: This is a guest article by Padmavaty S. With overall 7+ years of software testing experience she has extensive experience in testing Java, J2EE, MVC, and Struts framework.

Let us know if you are working on testing JAVA applications. Share your experience in the comments section below. Feel free to post your doubts and queries also. We would love to hear from you. 

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