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Software Testing - Test Harness

Software testing is carried out by both manual and automated testing. The manual testing is carried out by manual efforts however, the automated testing relies on usage of various automation tools like Selenium, Cypress etc.

What is a Test Harness?

A test harness is just like a testing framework. It is a collection of software, inputs, data etc created to verify a piece of software executing in multiple environments and then analyze its results. It is done to assist integration testing. A test harness is a bunch of stubs, drivers, and other tools that assist in automation testing and debugging. It provides the copy of the resources and configurations which are unavailable in the test environment.

Let us take a scenario where a piece of software has to be integrated with another software on PHP, however there is no PHP implementation during the development. In this situation, a test harness is created as a substitute.

A test harness consists of two segments test execution engine and a test script repository. The test execution engine is used to verify the software and the test script repository is the location where the test cases and scripts are saved. A test harness contains all the details required to compile and execute a test. It can be used for both integration and automation testing.

Characteristics of a Test Harness

The characteristics of a test harness are listed below −

It helps in automation testing and to invoke functions then compare the actual outcomes with the expected ones.
It is the holder of the developed code which can be verified by an automation framework. It allows specific tests to work, and examine its output.
It can be part of a deliverable code.
It can copy the actions performed by the actual software.
It aids in performing actions on the software which is being tested.
It can be integrated for composite frameworks.

Why is a Test Harness Used?

A test harness is used for the reasons listed below −

It helps to adopt automation testing, thereby increasing the productivity of resources and the software.
It runs the entire test suite and generates the test reports.
It helps to measure the code coverage.
It helps to handle the real life scenarios which are not easy to replicate.
It runs tests in a test suite using a framework, assists debugging the code, and tracking the results.
It is used to enhance the quality of software.

How is the Test Harness Created?

The test harness is created by using the below steps −

Step 1 − Both the testers and developers create test scripts to take care of particular scenarios, inputs, and data. It all begins with generation of the correct and sensitive data.

Step 2 − Post triggering the test harness, the testers ensure that they have run all the tests and generated results using a single command.

Step 3 − The execution results are gathered.

Step 4 − The expected and actual outcomes are compared to get the deviations and they are reported.

Step 5 − The test reports are generated, shared with the project stakeholders for further research.

Difference Between Test Harness and Test Framework

Sr.No	Test Harness	Test Framework
1	It is a group of stubs, drivers, tools etc that are required for test automation.	It is a set of guidelines, processes, etc which are followed to create new automated tests.
2	It has all the test case details, and the target deployment port that is used to compile and run the tests.	It has the reusable libraries, environment configurations, test cases, report generation etc.
3	There is no feature to record and play test scripts.	The record and play feature is available.
4	It can be used for automation and integration testing.	It can be used for data driven framework, keyword driven framework, hybrid driven framework etc.

In which Situations the Test Harness is Used?

The test harness are used in the below situations −

Automation Testing

The test harness is used as a framework for automation testing with certain settings to run the tests more efficiently. Once completed, a detailed report is created and shared with the testers and developers for more analysis and improvements.

Integration Testing

In integration testing, all individual components and units are combined and tested to verify if all them are working as expected. It is used to detect defects when multiple components are integrated and there are interactions among them.

An integration test can be done only after individual units are unit tested and ready. In actual scenarios, while performing integration testing, all of them may not be developed yet. At that time, drivers and stubs of the test harness are used.

What are the Test Harness Tools?

The different test harness tools are listed below −

JUnit − It is a unit testing framework used for test harnesses. JUnit is a unit testing framework for Java programming language. It plays a crucial role test-driven development, and is a family of unit testing frameworks collectively known as xUnit.
NUnit − It is a unit testing framework used for .NET

Advantages of a Test Harness

The advantages of test harness are listed below −

It helps to improve productivity.
It assists in test automation.
It can be used for debugging code.
It helps to find defects at the early stages of software development life cycle (SDLC).
It helps to gauge the code coverage.
It aids in covering complex use cases.
As the software is well tested at the unit level, it increases its stability and quality.

Disadvantages of Test Harness

The disadvantages of test harness are listed below −

It does not support record and playback features.
It requires technical skills and knowledge to implement the test harness.
It requires cost and time to create automated test suites using skilled resources.

Conclusion

This concludes our comprehensive take on the tutorial on Software Testing Test Harness. We’ve started with describing what is a test harness, what are the characteristics of a test harness, what are the differences between test harness and test framework, advantages and disadvantages of a test harness. This equips you with in-depth knowledge of Software Testing - Test Harness. It is wise to keep practicing what you’ve learned and exploring others relevant to Software Testing to deepen your understanding and expand your horizons.

FAQs

Q1. Why is it important to design a test harness for testing?

A test harness allows developers and testers to run automation more efficiently that eventually enhances productivity. Besides, it also helps in improving the quality of the software through debugging. It allows testers to schedule upcoming tests, especially in complex conditions. Apart from that, it also helps in automated report generation and recording test results.

Q2. What is the difference between test harness and test framework?

A test harness comprises a set of dummy programs (stubs and drivers) written in JAVA, .NET, etc., to promote interaction with software under test. It is made of information required to compile and execute test cases, stubs, TDP, source code files.

A Test Automation Framework contains procedures, intellectual concepts, and environments allowing testers to design and implement tests. It comprises test libraries, automated testing tools, testing platforms, and complying with best testing practices.

The concept of the difference between Test Harness and Test Framework falls under blurry lines. You can consider test harness as specific while test framework as generic.

Q3. What are some best Test Harness Tools?

Some of the tools for test harness fall under the category of automation software and test management software. One cannot execute a test harness with a single tool. However, a combination of tools like QTP, HP ALM, Junit, etc., are often used by testers.