Back To Back Testing What it is & How to Perform

Back To Back Testing: What it is & How to Perform?

Releasing a new software or a subsequent version requires clearance from various departments looking for minimum benchmark performance. This can be achieved by noting the values from the current version and comparing them with the later versions. However, this is far beyond the perfect infrastructure an organization should opt for. The problem here is the changes a software goes through in new versions are not just limited to the source code. Other changes such as server-based changes, architectural changes, user base changes, etc. put down a lot of differences in how things work currently.

To resolve this problem, back-to-back testing is used in software testing. This type of testing provides a clear picture of the two components that we compare to boil down to the best one among them. It is a simple, clear, and effective method to eliminate the issues through a comparison-based testing method.

What is back-to-back testing?

Back-to-back testing is a comparison-based method used to determine the most optimum component for our application. It need not be applied to a complete software but can also be performed on smaller components such as individual modules.

back to back testing


When we compare two entities in back-to-back testing, we are actually measuring the parameter values generated through certain actions on both of them. For this, we need to keep in mind that every input is exactly the same otherwise the input could affect the output. This solution works for two cases:

  1. When different components are tested.
  2. When the same component is tested but for different versions.

These two cases work in two different scenarios. For instance, let’s say back-to-back testing is performed when two different software are present. Here, the aim is to determine which software is better for us and is popularly used when a contract is given to more than one vendor.

Another case is when we need to test the component developed internally as an upgrade to the previous version. In this approach, we take the same component from the previous version and the aim is to check any performance-related bugs or performance-related improvements, if any. The new version should perform at least as good as its previous one. 

Since back-to-back testing’s core working methodology revolves around comparison methods, it is also called comparison testing in the industry.


For someone who has two entities that can take the same input and have the same end goal, the testers can prefer back-to-back testing for it. Cases such as POS machines, and algorithms used for the same tasks serve as perfect use cases for it.

One of the best examples in current times for back-to-back testing is the use of AI models and prediction algorithms. Consider we have a requirement to integrate a prediction module in our ten year old mobile application that can predict the price of a share based on past values. This will serve as an individual module that takes the name of the company and the year as inputs and predicts the price for that particular year. For example, this graph shows the predicted and actual share price for Facebook (now Meta).

back to back testing example


As we know AI models are quite popular and prediction algorithms are one of the most used algorithms across various domains such as healthcare, stocks, weather, etc. Therefore, naturally, they have become a popular choice for researchers and analysts who keep improving them or deriving new ones with newer models. So it is easy to find a couple of best prediction algorithms according to our use case.

To perform back-to-back testing, we choose two prediction algorithms and use them in isolation or integrated into the software. The latter option will take time but it is a safer and recommended approach. Now we open both the modules input the same company name and verify the results on both of them for 1 week later. While they both will have accuracy written on paper, it may not serve as a guaranteed percentage for our use case, and therefore back-to-back testing will help us explore the most compatible choice. Similarly, we can use two entities for other modules as well which will result in a good quality application.

How to perform back-to-back testing?

For someone going over back-to-back testing, for the first time, the next question would be to explore the methods of its execution. To answer this question, we have to look at two entirely different mechanisms of testing:

  • Manual back-to-back testing
  • Automated back-to-back testing


Comparison-based functions are often initiated using the manual method in any field of computer science to first guarantee that we are on the correct path. The issue with comparison functions is that they will generate only a certain output which is often “Component 1” or “Component 2” determining which component was able to run the test quicker. But to be sure that this method works, we need to manually scrutinize this comparison by inserting each value by ourselves. Due to this reason, manual back-to-back testing is often not an option but the initial step in this domain.

Manual back-to-back testing starts by setting up the same systems, installing the software, and manually inputting values of various kinds. For instance, if an algorithm is being tested, it needs to have input with best case, average case, and worst case. The main goal of manual back-to-back testing is to make sure the system we are setting up can be trusted with automation that will follow soon after this method.


The path to automation in back-to-back testing is easier one to follow than the one we discussed above. Since we are just working on comparing the models here, we need not worry about the functionality here. It is taken care of in functional testing and regression testing. While manual testing is all about the reliability of the system, automation’s job is to find the most accurate system and the most compatible one according to the application.

The job of automation back-to-back testing starts with creating test cases with most of them depending on some kind of input. For instance, clicking a button and checking if it works or not does not work as both the system can do that almost identically and there is no factor for comparison. Verifying network latency for some action, however, would certainly provide two results that can be compared and complemented. 

For both manual and automation back-to-back testing, a robust system is required on which a tester can rely. Having a physical system will work fine but the tester may not be able to expand it to multiple systems which is extremely important, especially in a web-based application testing or native application. Moreover, comparison testing needs logical test cases that we think can actually provide different results even on the same system. In such scenarios and considering that the time is limited, we cannot waste it on Googling out programming syntaxes. As a tester, it is much better if all our energy is invested in creating “tests” and not “programming scripts”. A perfect tool that complements all these requirements is a codeless test automation tool with cloud technologies integrated into it such as Testsigma

Testsigma is a cloud-based codeless tool that makes sure the tester can execute any type of testing without ever writing any script. This is achieved by applying natural language processing that can understand plain English language and convert it to actions automatically without any manual intervention.

Testsigma - Automation platform

Integrated with artificial intelligence to rectify the tests according to the UI changes, the self-healing mechanism facilitates the efforts of testers and sheds the load off them to wrap things faster. Back-to-back testing also requires a great reporting mechanism to document every little parameter value we wish to check. Testsigma comes with an in-built reporting module that reports every little testing detail not only through text but also through graphs and pie charts helping everyone analyze the reports quickly. Adopting such tools at the start of testing can help move things really quickly without losing the efficiency targets.

Steps to take for back-to-back testing

To perform back-to-back testing, there are a few generic steps that can be followed by the tester no matter which method they choose:

Document the test objectives

First, we need to define the objectives of our tests. This is important because we do not have established functionalities that we can just tick off from the list. There needs to be a careful analysis of the system and which areas will be targeted with the tests so that we get the most out of back-to-back testing.

Setting up a test environment

Setting the test environment is an important aspect of back-to-back testing as the tester has to make sure that both the components or software work in the same environment. The environment needs to be in the range of minimum requirements with target devices used for a better analysis.

Script the test cases

Based on the test case objectives and the environments, the tests can now be scripted. To conserve time in this process (as it could take a lot of time), it is advisable to choose a codeless testing tool.

Execute test cases

The scripted test cases can be reviewed by other team members or seniors to enhance the quality and ensure they cover every little aspect. After this process, the tests can be executed on the environment set up in step 2. As a recommendation, it is better to prefer real devices in this step rather than relying on emulators and simulators. If the organization can purchase them and maintain them in the future, that is alright. However, online tools such as Testsigma can provide that too. 

Collect data and reports

In this step, we collect all the data that has come as an output from the test execution from various places (such as various machines or servers). Similarly, we need to collect all the reports from various machines and create a single document for the next step. Tools such as Testsigma provide this functionality beforehand.

Analyze data and reports

In this step, we analyze the data we fetched in the last step. This is a time-consuming process and complete attention should be given to it. This step will explore the defects and help understand which component or system is more suitable to move ahead.

Document defects

All the defects found in the previous step require documentation that can be assigned to developers or other team members accordingly. In this step, it is best to use a bug-tracking system for quick results.

Document findings

After documenting the defects, we document our findings from the analysis. Findings refer to the comparison results, parameter values, and the final decision about which system is better suited for our work.

Create a test report

Lastly, we create a test report that will contain information from all the previous steps. It should list down the objectives we aimed for, the environment we had set up, the test cases we executed, data analysis, and anything else the tester finds relevant. The test report should also provide the final decision from the tester and the reasoning for the same. Since this is the document that will flow around among teams and non-technical people such as stakeholders, it should be crafted with detailed data and keep everything simple as well.

With these simple steps, no matter what type of back-to-back testing you are doing, it will keep it organized without any need to backtrack in the future due to any wrong move.

Benefits of Back-to-back Testing

The method of back-to-back testing provides an array of benefits that help provide additional quality to the application directly or indirectly.

The most suitable component is selected

Back-to-back testing uses a comparison method and compares various parameters to churn out the most suitable component for the application. A better-suited component when integrated will surely work more efficiently than the other one and will trouble the testers and developers less in the future.

Reduced maintainability

Since we are using a system that is most compatible, it will leak fewer times than what we would have gotten without any testing. Hence, in the future, fewer changes will be required which means maintainability will decrease considerably. This is extremely important as maintainability does take the majority of our time and costs as the project starts to scale up.

Help understand the system behavior

Comparison testing forces us to write test cases that provide a certain specific output when inputs are provided. What happens in between is the processing is done through algorithms and other logic is applied that drives that output from the component or module. Hence, through this, we ensure the core behavior of the module is intact which is one of the most essential things in any application.

Enhanced Performance

A better-suited system means it is most compatible with the working and the behavior our system exhibits. This is exactly what we aim to find out when we perform back-to-back testing on components or software. Naturally, due to this, we expect it to perform better and ideally provide the most optimum support for the application.

Minimize bugs

When fewer bugs leak, we will have fewer post-production bugs as well and less additional work for testers and developers. This means our application’s quality has improved to the point that it affects the end-user as well as the developers and tester in a big way. This is the end goal of any organization!

Reduced costs

Everything discussed above directly impacts the time a tester, an organization, a developer, and other team members need to invest in addition to their regular responsibilities. For all this time, salaries are paid to the people involved, and in addition, the project’s timeline gets exceeded as well which means additional time investments. Back-to-back testing reduced all this to a minor extent if not eliminate it completely. Therefore, we generate lesser bills for projects as well as internally which is always good news.

Constant time of testing

Back-to-back testing stands apart from other testing domains in terms of time of execution. In other testing domains, the total time taken is directly proportional to the size of the modification. If the modification is major, the time taken is large, and vice versa. However, in back-to-back testing, this is not the case. Here, the time remains the same even if the modification is a large one. Due to this, we don’t have to skip anything just because we don’t have enough time before the release and can ensure the quality of the application remains intact.

While these benefits tempt us to adopt the back-to-back testing paradigm into the current testing cycle, it is important to explore the demerits as well to calculate its effect on the application equally.

Limitations of back-to-back testing

Back-to-back testing suffers from the following limitations.

Too restricted

The thing that proved to be its strength can also prove to be its limitation for some organizations. Back-to-back testing’s range is fixed and restricted to only those elements that can somehow work on the comparison model. This also restricts the number of test cases and the areas these test cases focus on. Not all organizations would see back-to-back testing as an advantage therefore and could skip it due to time restrictions.

Limited to two components

When we need to line up the components among which we need the most suited one, we often find ourselves stuck with more than two components. For instance, the AI algorithms that we talked about, are often available from multiple developers and researchers. This becomes a limitation as back-to-back testing only allows testing two components among all. Since we do need to have the best-suited components, this means we spend a lot of time comparing each of them just like Bubble sort. This might not be acceptable to organizations working in extremely tight agile cycles.

Hard to interpret the test conditions

To compare two components, we need to make sure everything remains the same. This is a hard job because there are too many entities involved that are connected to the machines. These entities directly or indirectly affect the machine which in turn affects the test case outputs. For instance, a little fluctuation in the bandwidth on any of the machines can change the output produced. Keeping so many parameters is extremely hard to manage and becomes a limitation for the testers working on it.

Too few areas to work on

In this post, we have repeatedly mentioned how back-to-back testing can only be applied to functions that produce a certain output that can be compared. This cuts out most of the functional areas from the test focus. What we are left with is one small section of the total functional value that takes a lot of time to conduct from one end to another. Moreover, due to this, the behavior of the system cannot be interpreted and we might feel that we are investing too much for too little. This statement is subjective in nature though.

Needs specialized testers

Back-to-back testing is a uniquely different domain of testing. Even someone working towards the functional side may find it a bit challenging to explore the areas where comparison is required and write test cases over them. This means either the organization needs to find someone suitable explicitly or train the existing team members for the same. This process will consume time and additional costs for the organization.

Apart from this, the general limitations in testing do exist here as well such as the need to learn programming languages, cross-browser testing techniques, and so on. However, codeless testing tools like Testsigma can eliminate a lot of them through their robust infrastructure.


A lot of the time we are in one of the two situations. First, we have more than two options to choose from for our application. Second, we need to make sure that the new version is at least as good as the last released one if not better than that. Both of these problems are solved with back-to-back testing.
Back-to-back testing is a comparison-based testing paradigm that aims to find the most suitable component or module out of the two. Once we achieve this, we can integrate the chosen component into our application for the most optimum results. However, with so many crucial advantages such as reduction in maintainability and post-production bugs, back-to-back testing also possesses a few limitations that we would want every tester to go through once before starting. The aim of this post is to brief about this testing method that may not be so popular today but is extremely important for the health of the application. It provides an additional layer of guarantee on top of other types of testing with a good deal of contribution to end-user satisfaction. We hope it helps you in testing projects, in the future.

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