The Guide To Parallel Testing
Tags: paralleltesting, testgrid
Published: 2024-06-11 10:51:40

Automation entails boosting testability, but there is a roadblock in the path. The frequency of the massive amount of tests and the lack of time to test the features make traditional sequential automated testing insufficient.
As a result, the need for parallel testing arises. Yet, some people are reluctant to adopt parallel testing even though the purpose of Selenium Grid was to enable the running of parallel test cases. Not only does parallel testing reduce the budget, but it will also ensure quality assurance. 
In this article, we will introduce parallel testing to you so that you can increase your testing coverage in the next release cycle. 

## What is Parallel Testing?
Through “Parallel Testing,” the same suite of tests can be run parallel across different environments, device combinations, and browsers to maximize automated testing. Time and resource limitations are two main reasons for using parallel testing. 
In contrast to distributed testing, which requires interaction between test components, this type of testing does not require any such coordination between components.

Let us take a basic example and work around it. It will help you understand the concept better. For example, suppose you are interested in testing the functioning of a signup form. Then, you have built an automated test script to run the same. 
If you wanted to conduct this test on all 50 possible combinations of web browsers and operating systems, it would take you 100 minutes to do so, assuming that individual tests take 2 minutes to complete. So even if you automate testing and run them one after the other, it will take an interminable amount of time for your tests to finish running.
Imagine running the same tests, but you can now run three to four tests simultaneously, and your run time reduces. So it is how parallel testing works. Thus, the testing saves you from all the hard work.
So, the following variables play a significant role in determining the optimal number of parallels for improving test times:

- The current number of browsers and devices required to conduct the test.
- The number of tests that are being conducted concurrently at one time. 
- The Current Build Time
- The intended amount of time for the build, and 
- Finally, the desired number of browsers and devices required to conduct the test. 

## What Situations Are Suitable to Perform Parallel Testing Using Selenium?

Now that you understand how parallel testing in Selenium can be beneficial for the deployment and delivery of web apps, the next step is to learn when and how to deploy it in your software development life cycle. 
Here are examples of situations in which you could use parallel testing:

- Suppose there is even the slightest bit of doubt about the functionality of newly released applications. It arises when the upgraded and existing version of an application is identical, especially in the case of banks and financial institutions. 
- During the process of importing legacy data from one system to another system, an automated regression test suite can be a great help in ensuring that the transfer of everything is without a hitch.

## What Are the Benefits Of Parallel Testing?

Even though we’ve only barely touched the surface of what parallel testing is, how it affects the test cycle, and when it’s frequently employed, there are a handful of other reasons you might want to give it some thought.

**1. Swiftness**

While sequential testing takes much time, parallel testing allows you to split the total amount of time committed to testing by the number of different settings. If you want to test your application on five diverse devices, you just write one script and run it on each of your target devices. It will significantly lower the period it takes to assess your program by a factor of five.

 **2. Wide Coverage**

It is usually a good practice to run your program on as many different combinations of platforms, devices, and browsers as available to you. It is crucial to ensure that no bugs are left behind. You will see a considerable increase in return on investment (ROI) thanks to the parallel testing that brings your test coverage to a whole new level. 

**3. Economical**

The software and hardware used by testing teams to carry out test cases is referred to as a testing environment. Creating, maintaining, and constantly updating your test environment can be expensive. It might burn a hole in your pocket. 
However, maintenance is no longer an issue while performing parallel testing because you can execute tests in the cloud without any human intervention. can comfortably lease the up-to-date testing environment you require. In addition, cloud-based testing grids reduce the overall cost per test as it is updated every time.

4. The Transition from Sequential Testing on a Gradual Scale
Attempting to switch from sequential testing to parallel testing all at once is a monumental task that requires an approach with caution. It’s possible that beginning on a smaller scale is your best bet. You can get started with the test cases that are the most easy to convert and adapt in the parallel testing. It will give your engineers ample time to alter the rest of the tests.

**5. Allowing Testing Continuously**

Utilizing a technique that allows for continuous integration and delivery is an excellent way to release products of high quality in the lowest amount of time possible. Continuous testing calls for a shorter test cycle, which you can never accomplish using sequential automated browser testing due to the nature of the testing. 

However, parallel testing in Selenium enables you to take advantage of cloud computing and virtualization to run more tests quickly. Consequently, you will be able to get products into the marketplace in a shorter time duration. 

**6. Optimizing Processes**

The duration of time it takes for a CI/CD pipeline to complete its whole cycle is a prominent indicator of how well it performs. The sooner the team obtains a result, the sooner they can apply the repair, restructure, and repeat the process, as feedback loops are crucial in CI/CD. 
Further, it is possible to improve the pipeline’s performance by breaking down large test suites into smaller independent jobs and running them in parallel. 

It will buy you some buffer time and give you access to thorough documentation of test results. Later, developers can work on this documentation to identify and resolve code errors, thereby improving CI/CD processes. 

## How To Handle Parallel Test Cases In Selenium?

Creating a set of projects to test browser compatibility and then a master project to test all of those projects simultaneously is a typical approach to performing parallel testing. In Selenium, the criterion for parallel testing may often be broken down into two levels. The first is known as Entry-level criteria, and the second is known as Exit criteria.

Before beginning the execution of the test, we must establish the elements selected for the Entry Criteria. For instance, it includes setting up an appropriate testing environment, defining the pre-conditions for the automated browser testing process and the test scenarios, or performing the necessary migration of any new and legacy data.

Understanding the difference in test suite execution impact and measuring the output of a new system to existing systems can be prioritized as part of the exit level criteria. It can help ensure the project is completed successfully as bugs are detected and fixed quickly.
Read more : [What is Selenium](https://testgrid.io/blog/selenium-what-is-it/)

## What Are the Best Recommendations For Successful Parallel Testing?

Even using Selenium Grid, performing automated browser testing in parallel is more complex than you might think. The prime cause of the difficulty is the unstructured automation framework used in Selenium for the execution of parallel tests.
 
Implementing a parallel testing strategy that adheres to industry standards is essential to the method’s viability. The following is a list of successful strategies you can utilize when implementing parallel testing with Selenium.

## Conduct Tests in a Cloud-based Environment

One of the most common blunders involves a parallel testing strategy with the company’s internal resources. It is not an efficient use of resources to construct and maintain one’s own infrastructure. 

Not only will it save you time and money, but it will also prevent you from getting the most out of parallel testing, which offers significant benefits if you are able to do the tests with a high level of concurrent users. 
Additionally, you will need plenty of resources to maintain an up-to-date testing environment. For this purpose, it is a good idea to resort to cloud-based services that enable you to access devices and browsers by using cloud storage anywhere and at any time.

**Avoid Hard-Coding**
Embedding data directly into the source code, in contrast, to automatically generating at runtime, is an example of hard coding. Because it establishes dependencies between test cases, this strategy makes it impossible for you to run tests in parallel effectively. 

We advise you to refrain from hard-coding values while scripting your test cases. It will ensure that each of your tests is self-sufficient so you can execute them whenever it is required to do so. When configuring your test cases for parallel execution, use the data-driven approach instead of the traditional technique.

**Effective Management of Your Test Data**

Handling the test data most effectively is the fundamental factor in determining how well parallel Selenium test automation can be. However, you will need an efficient method to generate test data when required and eliminate it when it is essential. 

There are a few fundamental tactics for data management that can be useful: regularly updating the data, using RESTful APIs, and generating data for oneself.

**Avoid Dependencies Between Tests**

Dependencies between multiple test cases are a major factor contributing to the difficulty many teams experience when attempting to move to parallel testing. To put it another way, when different test cases rely on one another in some way, you need to execute them in a specific order. 

Failing to do so can render any parallel testing technique useless. Thus, ensuring that each test case is atomic and autonomous from the others is of the utmost importance. Only after that will you be able to run them whenever you want and in whatever order you want, liberating your testing procedures from any restraints.

## Are There Any Limitations To Parallel Testing?

Like every other automated testing system, even parallel testing has some drawbacks. You will find the following limitations in Parallel testing:

**1. Do Independent Modules:** 
We must have independent modules to test several modules concurrently. Additionally, you cannot use the parallel technique with modules that have dependencies.

**2. Detailed Understanding:** 

For parallelization to work effectively, it is essential to have a comprehensive understanding of the product’s functionality. Even though parallelization can aid in testing for cross-browser compatibility, its ability to cover a wide range of browsers is limited unless you use it in conjunction with distributed testing, which allows the development of different types of devices and browsers.

## Make Tests That Effectively Run In Parallel

If you’re planning to use Selenium’s parallel testing capabilities, you don’t want to take your time. Therefore, writing more than one test that can’t run simultaneously before your product is released is a no-no. So, think about parallelization while you create your Selenium test automation cases.
It is where you can test your planning skills. If you want to avoid the hassles and last-minute struggles, test your application for all possible combinations. Writing test cases that execute simultaneously is simpler, faster, and more effective.

## Final Thoughts

The expense of compatibility testing with parallel testing rises since it is necessary to have access to several different platforms and browsers to complete the tests in parallel. In addition, we may reach a stage where access to all devices and browser versions will no longer be available.

Source : _This blog is originally published at [TestGrid](https://testgrid.io/blog/parallel-testing/)_