Thread Testing

Software Testing and Quality Assurance are two significant parts of SDLC. These together assist software engineers in validating the quality, performance, and other important factors of the software product. Software testing consists of several planned and systematic activities, which ensure that software processes and products conform to the set requirements, standards, and procedures. In short, it is a process that checks, whether the actual result or output matches the expected results, while simultaneously ensuring that the software or the end product is defect free. This process is further made successful through the use of various testing techniques and methodologies, which work together to provide the most accurate as well as expected results. Thread Testing is one such type of software testing that is usually conducted during the early stages of System Integration Testing. This type of software testing technique is immensely useful in scenarios where an application is of a type that uses client server architecture.

Integration Testing at a Glance:

To comprehend the significance of Thread Testing, it is crucial for us to get a clear understanding of integration testing, as thread testing is a vital part of integration testing and is usually performed in its early stages. Therefore, integration testing is a process wherein individual software modules are integrated logically and tested as a group. Moreover, integration testing occurs only after unit testing and before validation testing reaches its culmination. The main focus of this type of testing is to check the data communication amongst the multiple modules coded by different programmers. When software application is tested through integration testing, it exposes the problems and issues with the interfaces among program components before trouble occurs in real world execution. This type of testing takes its input modules that have been unit tested, groups them in larger aggregates, applies tests defined in an integration test plan to those aggregates, and delivers as its output the integrated system ready for system testing. The various techniques used for executing integration testing are:

  1. Big Bang Approach: Here all the components are integrated together at once, and then tested. This type of testing is convenient for small systems.
  2. Multiple thread testing: This type of testing is done by joining tow or modules that are logically related, wherein other related modules are added and tested for proper functioning. This type of integration testing is carried out through following ways:
    • Top Down Approach
    • Bottom Approach
    • Sandwich Approach

What is Thread Testing?

Thread based integration testing plays a key role in the success of a software project. Performed at the lowest level, it provides the integrator with the basic as well as better knowledge of the scope of what to test. It is a methodology, which is used in testing applications based on client server architecture. A thread is the smallest unit of work that can be carried out by the system and it is mainly used to verify the functional capabilities of a specific task or thread. In thread testing, testers focus on testing individual logical execution paths in context of the entire system.

Each of these threads has a status associated with it for a particular build. Performing thread testing on valid business transaction through integrated client, server and network is very critical. Thread are integrated and tested incrementally as subsystems and then performed as a whole system. As thread based testing is one of the incremental strategies adopted during the system integration testing, is should be known as “thread interaction test”. Moreover, this type of testing is suitable for real time and object oriented systems and it is based on testing operation, which involves a sequence of processing steps that thread their way through the system.

Different Type of Thread Testing:

Thread testing not only serve as the base for integration testing, it also tends to drive the entire software development effort from scheduling to status reporting. It represents the system, which has a documented definition and general execution path, an internal design and an associated test. This type of testing is suitable for real time and object oriented systems and is based on testing an operation, which involves a sequence of processing steps that thread their way through the system. Thread testing usually starts with single event threads and then goes on to multiple event threads. Complete thread testing is impossible because of the large numbers of event combinations. For this reason, thread testing is basically divided into two types, which are:

  1. Single Thread Testing: Single Thread Testing involves one application transaction at a time, wherein it sees how it behaves. This enables the tester to test the program logic, and also shows them whether the information provided is correct or not.
  2. Multi Thread Testing: Multi thread testing is a process that involves several concurrently active transactions at a time. In this type of thread testing, all the transactions are in the same region, so one can readily test the ability of a new transaction to coexist with them. Moreover, a transaction that works perfectly in its single thread testing still fails in multi thread testing and it might even cause other transactions to fail or even terminate.

Challenges in Thread Testing:

While conducting thread testing during the early stages of system integration testing, a tester can come across several difficulties and challenges that can affect the time and cost of testing as well as the performance of the end product. These challenges and hurdles can further increase the testing efforts required for the process of testing and therefore should be considered before initiating or executing the whole process. Hence, the challenges encountered while performing thread testing are:

  • The biggest challenge in thread testing is for multi thread testing, wherein one should be able to program reproducible test for unit test.
  • Writing unit tests for multithreaded code is another challenging task.
  • As the testing criteria vary for both multi thread testing and single thread testing.
  • For multi thread testing various factors such as memory, size, storage capacity, timing problems, etc. vary when called on different hardware.


Conducted during the early stages of Integration Testing, Thread Testing is used to verify the major functionalities as well as the capabilities of a specific task or thread. Thread based testing is a generalised form of session based testing, in which sessions are formed of threads. However, it is not necessary that a thread is formed of or is a session. The ideal way of carrying out thread testing is to integrate threads incrementally first at subsystems and then at the system level, which is then tested by the tester. Thread testing is a very useful testing technique if an application uses client server architecture. Even though one can encounter several challenges while performing thread testing, there are numerous advantages of executing it. With its assistance software engineers can easily test the functionality as well as the capabilities of the application or a specific thread or task. With its two types –single thread testing and multi thread testing– testers can check the transactions of the applications. In short, through thread testing one can validate whether the software is able to carry out all the transactions as per the requirements.