Test Harness in Software Testing | Usage, Examples, & Benefits

May 10, 2024Ritika Kumari
Test Harness in Software Testing Usage, Examples, and Benefits

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An application undergoes testing way more than it goes through the development and modification phases. First, developers perform Unit testing. Then after production is complete, QA verifies multiple aspects, including Performance, Functionality, Integration, Regression, UI, and more. Evidently, having a collective of software, test data, test drivers and stubs, and testing tools to validate an application under varying conditions will simplify the testing process; this collection is called a Test Harness. Especially, test harness refers to drivers and stubs, which are programs that interact with the application under test (AUT). Often used synonymously with an automated test framework, a Test harness is a group of all the elements, tools, and data you require to check an application under test (AUT) in different situations. We outline this topic in the blog to help you understand why and how test harnesses are imperative for your business.

What is Test Harness?

As mentioned earlier, a Test harness is a collection of testing tools, test data, software, drivers, and more to facilitate the software test automation process. It consists of all the detailed equipment and elements a test automation process requires. Once the test automation is complete, the behavior and output of the application testing process are monitored. A subsequent report is also generated.

It is an essential part of the software testing strategy that assists QAs in testing each application feature in detail. It includes executing automated test cases to generate the output and reporting them to developers. Then, coders can analyze the reports to identify the issues and perform the necessary fixes.

Why Use Test Harness?

The primary reason to use a test harness is that they are external to the AUT. And replicate the resources or elements that are still unavailable in the test environment. For instance, if you have an application with different modules that require connection with other systems, a test harness can help you out. If the external system is not yet available during the development phase, you should create a test harness as a replacement to continue with the testing process.

Another reason is that a test harness consists of the test execution engine and the test script repository. The former is the software that performs the test, and the test script repository is the location to store test scripts and cases. This way, you have all the necessary testing requirements in one place, which are all easily accessible.

Benefits of Test Harness

There are numerous benefits to using a test harness for the testing process. We list down a few of them here:

  • It helps automate the testing process to simplify and improve overall productivity.
  • It contains all the necessary tools and data to execute test cases and suites in one place.
  • Developers receive a detailed report with all the relevant information to pinpoint the issues found during the automated testing process.
  • It helps developers to measure the test coverage at the code level with high accuracy.
  • Test harness in software testing helps to simulate and handle complex conditions to support testers in efficiently managing such situations.
  • It is instrumental in debugging and enhancing software quality.

Key Features of the Test Harness

While the benefits of a test harness will aid you in understanding the necessity of the process, the key features will help you find the exact reason why you should opt for a test harness.

  • Supports automation of tests
  • Monitors and record test results
  • Provides flexibility and support for debugging
  • It helps developers measure the test coverage
  • Execute test suites in the right testing framework
  • Manage and input data tests in the AUT
  • Supports test case optimization

When and Where to Use Test Harness?

There are multiple instances where you can use the test harness. But predominantly, there are two major tests that benefit mainly from using a test harness: Automation and Integration testing. Let’s discuss them one by one.

Automation Testing

In automation testing, test harness functions as a framework that consists of test scripts to run different tests and generate reports with the results of all the executions. Developers can analyze the report to identify the issues, if any, and make improvements.

Often, the right approach to automation testing is when there is a need for running repetitive tests, complex test scenarios, smoke testing, data-driven, and performance testing.

Here is a guide with in-depth discussions on do’s and don’ts of automated testing.

Check out the guide

One instance we can talk about is verifying the data before moving it to the testing tool and receiving proper reporting and analytics for the same. Testsigma data management, along with the feature to get the right report and analytics, allows you to add to your test harness system and improve the testing ability multifold.

Integration Testing

We know that Integration testing is validating the connection between two sub-systems of an application to check if they are logically working as per the requirement. And In Integration testing, many developers rely on stubs and drivers to complete the system for testing. Stubs/drivers take the place of the missing module to enable testers to continue the testing process. Without them, they would have to wait for developers to finish working on all the modules, integrate them, and then start the testing process. In case you have to combine the homepage with the login page and add a payment gateway, integration testing comes into the picture here.

First, you must logically connect all these separate elements and test the flow of data between them. Perform unit testing on the login page and check if it integrates logically with the payment feature. But if any of these two pages are missing, a part of the test harness can act as a stub or a driver to replace the modules and continue the testing.

Here, the test harness includes all the documents and tools for planning, designing, developing, and using stubs and drivers to perform Integration testing.

Examples of Test Harnesses

Let’s take some examples of test harnesses.

1. Consider an e-commerce application that offers users décor items. The website consists of several modules: homepage, product pages, cart, Wishlist, and payment gateway, to name a few. You need to test every feature of the site and ensure that no issues slip away. However, it is difficult to perform the entire testing process in one single shot. With Testsigma, you can run the test cases across 3000+ real devices and browsers. Your testers do not need to spend much time writing test cases and maintaining input data. Testsigma allows you no-code testing with test data management options. And you receive reports and analytics documents to share with all your stakeholders. You can also integrate our test automation tool with multiple bug-tracking tools, CI/CD software, and collaboration platforms. And all of these different aspects would come under test harness for this particular testing.

2. Another example is in terms of integration testing, which undertakes two or more elements to make a functioning system. We can take the example of a login page (of the above e-commerce website) that takes the user to a dashboard with their purchase history, settings, notifications, saved addresses, and more. First, you would need to establish a logical connection between all these modules and check how they are linked. Then, you must execute integration tests on all the features. The test harness, in this case, will include all the systems, requirement documents, test scripts, automation tools, and stubs/drivers corresponding to any missing modules.

3. Suppose you are doing Functional testing using Testsigma tool to organize, manage, execute, and monitor the scripts along with handling the test data. For this, the test harness would be Testsigma, test data, test cases, test scripts and their storage location, test results, and elements that compare and monitor test results. And you can handle all these attributes using Testsigma tool easily.

4. For Unit testing, developers execute the testing process on the code or module they worked on. The test harness for Unit testing would include the test code developers create, the tool they use to run the script, and the output they receive.

Test Harness vs Test Framework

While test harness and test framework are usually thought to be similar, they have small, visible differences. Here are some of the clear differences between a test harness and a test framework.

Test HarnessTest Framework
It is a collection of drivers and stubs that are a requirement in software testingIt is a set of procedures, processes, and test environments in the automation testing setting
Record & Playback testing option is not availableRecord & Playback testing option is available
Covers all the relevant information for compiling, testing, and software deploymentIt consists of information like test libraries, scripts, tools, test environment, and so on
Comes in two categories: automation and integration testingComes in multiple testing categories: data-driven, code-based, keyword-driven, hybrid, and more
It is specific to the testingIt is a generic process
Contains a collection of dummy programs to maintain a relation with application under testContains a collection of dummy programs to maintain a relation with application under test 
Consists of logical concepts, environments, and so to design and run the tests 

Wrapping it up!

Testing an application requires data, test scripts, test environments, output recording and analysis, and integrations. And no matter how much you try, you cannot check all the aspects of your software in one shot. Having a test harness helps you to keep a collection of all the necessary features, tools, data, and more to make your testing process smooth and easy to conduct. All you have to do is gather the required materials and use them whenever the situation calls for it.

Your best bet to use a test harness for your software testing purpose is to use tools that support the process. Testsigma is a test automation tool that consists of several features ranging from test data management and data-driven testing to regression testing and report and analytics, which are all the essential parts of a test harness. Check out the tool demo here and sign up for a free trial to see our tool in action.

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Frequently Asked Questions (FAQs)

Why is it called a test harness?

Harness refers to a tool or equipment to control something. Test harness derives the meaning from the same idea. It means having a collection of tools or equipment in one place to perform the testing process.

What is the context where the test harness is used?

A test harness is used in two places for software testing: Automation testing and Integration testing. In automation testing, it is used for running test scripts and storing test data. In integration testing, the test harness uses stubs and drivers to replace missing modules.

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