ISTQB - Testing Levels

There are different testing levels are available in software testing. We have seen that software development life cycle have so many phases like requirement gathering, Designing, development, Testing & Maintaining the product. This all phase have testing steps as testing is required in all level of software development. We have seen all models of the software development now we will understand about the testing levels in detail. First of all we will need to identify that why testing levels have been came to the picture. Testing levels are required to remove overlapping of software development life cycle. We can identify missing areas of development life cycle by testing levels. There are various level of testing is available. Like Unit testing, Component testing, Integration testing, System testing and Acceptance testing. Let’s take understanding of each one.

1. Unit Testing:

Unit testing is the first step of testing levels. Here development team will perform the testing round before giving the release to the actual testing team. Developers will execute all the test cases which have been written by testing teams and afterwards handed over the release to them. Unit testing is distributed among the developer team like wise they have developed the code. Respected area of the testing will be distributed among the developers. They will use the test data which have been given by testing team. Main aim of unit testing is, all the functionality will be met to the requirement specification or not. So basically the code testing can be known as unit testing which is done by developer team.

2. Component Testing:

Now let’s move to the next one, this is component testing. We also can named it as module testing. In component testing, whole module will be tested but in unit testing only code will be tested. This is the main difference between unit testing and component testing. We can take an example of uploading the file of particular user. Here Login of the user will be one module & Uploading the file is second module. This both module needs to be tested individually as they both have different requirement and this both are developed by different developers. This will be tested one by one like first of all we need to do login of the user and then we can upload his data.

3. Integration Testing:

This is the 3rd testing level in which integration of two modules have been identified. Two modules which are integrated with each other, their functionality and behavior will be tested here. All the integrated modules should be work as expected. It have different kind of approach like big bang integration technique, Top down & bottom up technique, functional incremental technique etc. It may possible that component integration testing and system integration testing can be a requirement for some product. Integration testing have two sub testing levels as component integration testing & system integration testing.

We can take above example for component integration testing as we need to test that  user login needs to be done first for uploading the respected data on user account. Here integration of two module is required and this should be tested, if user will not have login details then he should not be able to upload the details OR with wrong credentials, user should not be able to upload the data.

System integration testing can be also required when we need to run more systems in one environment. 

4. System Testing:

System testing will be done by the tester team and they need to identify the compatibility of the application or product. System integration testing will be done after the system testing will be done or we can do it parallel too. Compilation of the product should be done as per the requirement that is the main moto of system testing. Load & performance of the application should be done here.

5. Acceptance Testing:

Acceptance testing will be done to identify that all the requirements of the product will be satisfied and product is working as expected. This testing will be done by the end user or customers. This level have 3 sub level. 1. Alpha testing, 2. Beta testing, 3. Gamma testing.

In alpha testing, Product will be tested in organization itself. Developer team or testing team will do testing as end user. Beta testing will done by the some users who will going to use the software and gamma testing will be done by when some specific requirement will be developed and that will be tested by leaving all the in house test activity.