Test Harness

What is ​Test Harness?

The test harness is composed of 2 words, i.e. test and harness. Harness in literal terms means a set of fittings by which any animal can be fastened to a cart, controlled by the driver. Similarly, test harness as the name suggests refers to the software system that contains test drivers, test scripts and other supporting tools that are required for the execution of any test case. It provides the stubs and drivers (dummy substitute programs used in place of the undeveloped module) for the test execution. To execute the test using test harness requires the use of the Test library and generates the output and enhanced reports of test results according to the comparisons between the actual and expected results. As a whole, test harness contains test repository and execution engine in which test repository holds all the test scripts of the test cases that need to be executed and the execution engine is the one which is responsible for testing those test scripts. The test harness is basically used for Integration and Automation testing.

Why do we need ​​Test Harness?

Below given are some of the points highlighting the importance of test harness in testing any software application

1. Gives the right path before performing the testing of any application.
2. It helps to measure the code coverage which is very helpful for developers in the early stages of testing.
3. Helps in the testing of a specific module of an application even if the other modules are undeveloped through the use of Stubs and drivers.
4. Automates the whole testing process which in turn helps in increasing the overall productivity of a project.
5. Helpful in handling difficult situations like communication with various libraries, and other tasks which are sometimes difficult for testers to deal with it.
6. Generates the enhanced reports of the test results by comparing the test results.
7. Test harness supports the debugging of the test cases executed at the same time.

Role of the Test Harness​ in Automation Testing

In Automation testing, test harness refers to the framework that contains the test scripts (general y written in any programming languages like Java, Python, Ruby, etc) and the test data (which is stored in a file, any other physical location or dynamical y provided at run time) to run the above created test scripts, gather the results of each test script and providing the enhanced charts/ reports for the test results by comparing the actual and expected data. All the data, conditions, scripts, results and software are a part of the in Automation Testing.

Role of the Test Harness in Integration Testing

As we are well aware of the term Integration Testing, which checks that the flow if two or more modules when combined together should work properly as a whole or not. In order to perform the Integration testing, the code of both the modules should be fully prepared and ready to test but this is not practical in real life, many times either of the module is underdeveloped. In order to handle such situations, and starts with the Integration testing, stubs and drivers (substitute piece of code used in place of undeveloped or undeveloped module) are used (basically y have an important part of the module which is interacting with the other module) is provided by Test harness in order to perform the successful Integration test. The integration test ensures that the integrated modules work as expected as a successful unit test for each of them. Automated scripts are created in order to perform testing of Integration tests. All the test script creation, test execution, framework, stubs, and drivers altogether form the test harness in Integration testing.

Features of Test Harness

Below given are some of the important features

1. To execute the automated test scripts using the predefined framework or test harness.
2. To record the results of the various test scripts executed.
3. Provide debugging of code using test harness.
4. Providing help to developers by providing the code coverage at the code level.
5. Increasing the speed of the testing process by performing automation testing.
6. Comprises of all test tools, test scripts, and test data which are required for the execution of test cases.

Test Harness Tools

Below mentioned are the 2 tools that are commonly used in the test harness

1. JUnit

​Junit is an open-source framework written in Java language used to create and run the automated test cases and perform the unit testing of the Java program or the applications written specifical y in Java.

2. NUnit

​Like NUnit, it is also an open-source framework written in the .NET language and is used to create and execute the automated test cases and perform the unit testing of the .Net application only. It is used to perform Test-Driven Development (TDD).

Difference between Test Harness and Test Framework

Some people always get confused between the test harness and test framework. But there is a minute difference between the two and as a tester or developer, it is very important to understand it. The test harness is a collection of software, test data, test scripts, stubs and drivers whereas Test Framework is a set of procedures and the environment in which automated tests are designed. Test Harness is used in the above two mentioned scenarios, i.e. Integration and Automation testing whereas Test Framework can be used for various testing like data-driven testing, keyword testing, hybrid testing, etc. Test harness does not al ow the testers to record and playback the execution of test scripts whereas Test Framework allows the record and playback of test cases.

Conclusion

The above explanation clearly depicts what the test harness is and why is it so important? One of the biggest advantages of using the test harness is that it helps to find the issues in the early development stages which in all increases the overall productivity of an application as the refined application resolving most of the code issues is delivered to them. It adds confidence as the unit testing (basically y the testing at the code level ) is done right. As the test cases are automated in the test harness, it also helps in saving a lot of time and proving efficient results to the client.

Recommended Article

This has been a guide to Test Harness. Here we discuss what is test harness, different types of tools & features and the role in integration and automation testing respectively​. You can also go through our other suggested articles to learn more –

1. Stability Testing
2. Security Testing
3. Static Testing
4. State Transition Testing