The Various Testing Levels in Software Testing

Software testing is looking into the functionality and correctness of a software. Moreover the testing process also involves identifying defects, flaws or errors in the application code. Furthermore, there are various testing levels in software testing.

The success of the different levels of software testing lies in selecting the right level of test at each stage in a project. These varied integrated stages are known as level of testing.

Let’s jump over to know the different levels of testing.

Various Testing Levels in Software Testing

The five levels of testing involved during software development by software testers and a testing team are,

  • Unit Testing
  • Integration Testing
  • System Testing
  • Acceptance Testing and
  • Regression Testing
Various Testing Levels in Software Testing

1) Unit Testing

Unit testing also known as component testing, is the first and lowest level in the testing phase. Here a programmer tests the individual units/components of software. In unit testing hidden bugs are exposed.

Furthermore, unit testing focuses on implementation. Therefore, a thorough understanding of the systems functional specification is required.

Significantly, you need an optimal level of documentation to do unit testing. The minimum requirements for documentation are,

  • It must be reviewable
  • The records must be archivable and
  • The test should be repeatable.

Additionally, there are two types of unit testing, namely, Buddy Testing and Automated Unit Testing.

Buddy Testing

Buddy testing involves a team of two developers. One writes test cases and the other one performs the unit test. Some of the advantages of the Buddy Testing team are,

  • Models of the program specification requirements are met properly as the test cases are created prior to coding.
  • Cross-training on application is provided and
  • The testing process is more objective and productive.

Automating Unit Testing

Unit testing is automated and is performed within the IDE of programmers. JUNIT is an example of automated unit testing. Furthermore, RUTE-J which is a randomized unit testing example of JAVA is an effective method of testing.

2) Integration Testing

This type of testing is performed either by a developer or an independent tester. This involves combining and testing different units of the program.

The purpose of this testing is to verify functional, performance and reliability requirements placed on major design items. Moreover, there are four types of integration testing, namely,

  • Big Bang Integration
  • Bottom-Up Integration
  • Top-Down Integration and
  • Sandwich Integration

Big Bang Integration Testing

During this testing all the units are combined together and tested at one go.

Bottom-Up Integration Testing

Here testing starts at the bottom of the tree. Moreover test drivers are used to drive and pass appropriate data to the lower level module. During each stage of bottom-up integration, the units at the higher levels are replaced by drivers.

Top-Down Integration Testing

Here testing starts from the top and then proceeds to its child units. Moreover, any other lower level nodes that may be connected should be created as a stub. Furthermore, as you add lower level code, stubs are replaced with actual components.

Sandwich Integration Testing

In this testing, the functionality of both bottom-up and top-down approaches are combined. Significantly, less throw away codes are used by sandwich testing when compared to top down approach.

3) System Testing

Core level of testing is done in System Testing. This testing is done when the system has been deployed onto a standard environment and all necessary components have been released internally.

System Testing - Testing Levels in Software Testing

Significantly, System Testing reduces cost, it increases productivity and reduces commercial risk. Moreover, in this type of testing, the system is evaluated as a whole and not in part. Furthermore, Systems Testing has two forms, namely,

  1. Structural Techniques and
  2. Functional Techniques

Moreover, both forms contain varied testing types. The Structural Techniques have,

  • Stress Testing
  • Recovery Testing
  • Operation Testing
  • Compliance Testing and
  • Security Testing

Likewise, Functional Techniques comprise,

  • Requirement Testing
  • Regression Testing
  • Manual Support Testing
  • Control Testing and
  • Parallel Testing

4) Acceptance Testing

In this type of testing, the system is tested for user acceptability. In simple words, acceptance testing checks the system against requirement. Furthermore, this testing is done before making the system available for actual use.

Moreover, acceptance testing also involves compatibility testing which happens when a new system is developed to replace the old one.

Acceptance testing involves four categories of testing, namely,

  1. Internal Acceptance Testing
  2. External Acceptance Testing
  3. Customer Acceptance Testing and
  4. User Acceptance Testing

Internal Acceptance Testing

This is otherwise called alpha testing which is simulated or actual operational testing.

External Acceptance Testing

It is done by the external and not employed in an organization that developed the system.

Customer Acceptance Testing

Here testing is done by the customers who asked the organization to develop the software.

User Acceptance Testing

This is otherwise called beta testing. Moreover, this is an operational testing by potential and existing customers at an external site. Nothing is involved with the developer. This testing determines the satisfaction of the customers.

5) Regression Testing

This testing is done when the software or its environment is changed. Moreover, it is a testing of a previously tested program following modifications. Furthermore, Regression Testing involves two components, namely,

  1. Adaptive Maintenance and
  2. Corrective Maintenance

Adaptive Maintenance

Here the system specification are modified. Moreover, it requires the generation of new test cases to suit the new specification.

Corrective Maintenance

Corrective maintenance is done when a maintenance technician discovers a problem while completing preventive maintenance, inspection, general or emergency work order.


Software testing saves time and money by identifying errors early. Furthermore, it ensures customer satisfaction. Software testing various for different business requirements.

Significantly, many today take software testing training courses. This is because software testing skills are in huge demand in many IT companies. You can opt to take a course from a reputed software testing training institute in your city. Furthermore, you get software testing training and placement from private professional institutes.

To sum up, software testing should comprise the following,

  • Cost of failure
  • Identifying defects
  • Reduce the risk of releasing and
  • Analyzing and evaluating a product from an independent perspective.

| About the Guest Author:

Guest AuthorIsaac John is working as a Content Manager at Zuan Education. He is interested in writing research-based articles on updates in software testing and other relevant technologies.

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