A Complete Guide to Distributed Testing

Testlio

November 1st, 2024

As systems scale globally, unexpected issues like network delays, data inconsistencies, or synchronization errors arise. This is where distributed testing comes into play.

Distributed testing ensures that all parts of the system work together reliably despite geographical or network differences. It verifies system robustness, fault tolerance, scalability, and performance. 

In this article, we will explore what distributed testing is, why it is important, and how Testlio can help you adopt it in your enterprise. 

What is Distributed Testing?

Distributed testing is a strategy that involves executing tests across multiple machines and systems. It is used to test large-scale applications or systems where more than one machine is needed to handle the workload.

Distributed testing builds a well-coordinated and synchronized test environment that mirrors real-world conditions across different parts of your system.

In distributed test systems, test components are not isolated. They actively interact and synchronize in every test run. This coordination ensures that all parts of the test are cohesive. 

After all test executions, results are collected from multiple machines and accumulated in a single report for effective analysis. 

Why is Distributed Testing Important?

Traditional testing methods fail to fulfill the demands of large-scale systems with multi-level architecture,  numerous components, services, and integrations. As these methods use a single testing machine and environment, they fall short for performing distributed functional and non-functional testing.

On the other hand, distributed software testing enables teams to distribute test execution across multiple machines. It simulates real-world user loads on complex systems globally.

Here’s why it is essential to adopt distributed testing before going into production:

1. Parallel testing for faster results: In distributed testing, multiple tests run simultaneously across nodes, mimicking real-world conditions. This reduces test execution time and objectively assesses system behavior under load.
2. Efficient resource management: QA teams use multiple nodes and data partitioning in distributed testing. This distributes the workload across resources and does not overwhelm a single machine.
3. Overcomes single-machine limitations: Distributed testing removes scalability bottlenecks in testing and development by using tools like Kubernetes. It ensures that auto-scaling and high availability are implemented in all the microservices and databases.
4. Enables realistic testing: Using distributed testing, testers can create environments that mimic real-time user devices and configurations. This helps identify bugs or issues that might only arise in specific setups and platforms.
5. Consistent regression testing: Continuous distributed testing ensures that testing is an ongoing activity. It guarantees the smooth integration of new features by identifying regression issues early.
6. Handling complex test data: Complex test scenarios need testing against multiple test data sets. Distributed testing simplifies data management by using data segmentation and partitioning. It verifies the application is tested thoroughly with all test data samples. 

Key Concepts of Distribution Testing

Distributed testing involves breaking up the test execution process across multiple machines or environments. Testing across multiple machines is a complex process and requires technical expertise. 

To effectively implement distributed testing, QA teams should know the following key technical concepts:

• Master-slave architecture: It is a highly scalable distributed testing strategy in which teams assign one master node and several slave nodes. 

  The master node controls the execution of the tests, coordinates tasks, distributes test scripts, and gathers results. The slave nodes are responsible for executing the test cases assigned to them by the master. 

• Load generation and distribution: In distributed testing, Load generators are used to divide the user load across multiple systems. 

  These dynamic and custom-built load generators simulate high traffic to mimic the high-priority user flows.

• Synchronization of test cases: When tests are run across machines, they must be synchronized to avoid race conditions and deadlocks. QA teams ensure that certain actions, events, or transactions happen synchronously in distributed test systems. 

  This is especially important for testing interdependent components, such as API calls or database interaction.

• Data partitioning and segmentation: Distributed testing can utilize data partitioning and segmentation to distribute the workload. In data partitioning, each machine (or slave node) is assigned a different subset of the test data, allowing it to handle part of the overall testing task. 

  Data partitioning is useful when the application under test interacts with large databases and processes heavy data.

• Geographical distribution: Distributed testing allows testing from multiple geographic locations. Testers can measure performance differences caused by network latency, bandwidth, and environmental factors. 

  This provides a realistic picture of the global user experience.

• Log aggregation and result collation: Since distributed testing involves multiple machines, collecting logs and results from each node can be challenging.

  Distributed testing has a built-in log aggregation mechanism to collect logs from slaves and centrally store them in the master node. The master node aggregates the results in a single report for detailed analysis.

• Dynamic resource scaling: Cloud-based distributed testing setups guarantee on-demand provisioning of resources during test execution. 

  This allows teams to adjust the number of load generators or test nodes based on the size and complexity of the tests, reducing cost and improving efficiency.

Distributed vs Non-Distributed Testing

QA teams determine whether to implement distributed or non-distributed testing based on the use case, domain, and anticipated application load. To make informed decisions, teams must understand the differences between the two approaches. 

Let’s compare them side by side for a clearer perspective.

5 Ways Distributed Testing Helps You Ship Updates Faster

The global workforce is increasingly shifting towards a remote or hybrid work model. Many workers state that the ability to work from anywhere positively impacts their performance.

This distributed workforce is a modern approach. It includes in-house office workers, as well as remote employees, contractors, vendors, and agencies. In other words, it’s the total of the strategic and agile combination of resources that the organization needs. 

Although distributed testing has organizational challenges to agile software development, there are plenty of advantages too. A remote, distributed team of quality assurance testers can help engineering teams ship updates faster than a QA team that works out of a single office. 

Following are five key ways in which distributed testing speeds up product releases.

1. Evening testing

With distributed testing, testers are often in multiple time zones. Of course, your team could be distributed across a single time zone, but for large organizations making strategic use of the global workforce, this is unlikely. 

When working in different time zones, it’s easier to deliver test results faster. For example, Strava uses Testlio to get testing achieved within 48 hours. This speed is partly due to a global network of testers that can test during different time zones. Strava delivers the release on a Wednesday and receives the results on a Friday. That level of speed wouldn’t be possible if all of the testers were in one location. 

2. Weekend testing

Time zones come into play on the weekend too. It is possible to get QA done over the weekend. If you work with employees and individual contractors, they might not be easily persuaded to test releases over the weekend. 

However, with advantageous time zones, it can still feel like your team is testing on the weekend, even if they’re not. Let’s say that your QA engineer, who lives in California, delivers the release to your testers, who live in Israel, on a Friday afternoon. The testers can test on Monday and Tuesday, and the QA engineer can get results back on Tuesday morning. He’s only waited for one workday, instead of two. 

While time zones can work in your favor with a distributed in-house team, it’s most convenient when working with a testing vendor that taps into a professional, global network of testers. 

3. Realistic localization testing

If you have high-quality standards for localization testing, you need a distributed QA team (unless you want to risk slowing things down).

Localization testing often includes these key things:

• User interface
• Content
• Application’s language support
• Localized hardware compatibility
• Cultural appropriateness
• Typographical errors
• Address formats and date formats
• Hotkeys, text filters, and other technicalities

When you combine the depth and breadth of localization testing with several different markets (each with their own cultures and dialects), you’re left with a very complicated testing cycle. 

There are two dangers with having a testing team that exists in one location. First of all, there will be an issue of speed and capacity to handle the localization quality requirements. Secondly, you’re far less likely to have testers who are genuinely knowledgeable in every key culture or language all in a single office. They might be checking off the basics without knowing the nuances of spelling, appropriateness, and various other expectations. 

On the other hand, with a distributed testing team, you gain real localization from native speakers – and you also achieve this in less time because people can be testing simultaneously across various time zones. 

4. Unique skills and responsibilities

Companies with distributed workforces tend to be more creative and adaptive. Because they require increased operational and partnering agility, they have a good handle on which roles need to be in-house to be successful and which ones can yield better results when outsourced to a vendor. 

While some larger organizations might bring together distributed testers from various offices to satisfy time zone requirements, localization needs, and level of skills, most companies will struggle to employ all of the testers they need. These organizations will be more likely to use in-house QA managers in combination with external partners to source the unique skills and responsibilities required to satisfy testing cycles – paying for additional capacity only when it is necessary. 

That matters a lot for QA testing. Your engineering team might need a burstable team of testers for three days, and then not need to work with them again for two whole weeks. Distributed testing gives your organization the freedom and flexibility to build the right relationships with the right resources. 

On the other hand, without distributed testing, your company has to choose between hiring all of the testers needed during releases and not making full use of them in between idle periods, or not recruiting enough testers and not living up to customers’ expectations for a quality experience. 

5. Different devices

With around 1.5 billion smartphones sold worldwide each year, it’s impossible to test every possible device your customers might own. However, good device coverage for popular smartphones, tablets, and IoT devices remains essential, as small differences in hardware can have a significant effect on the customer’s digital experience. 

With that in mind, organizations engaged in distributed testing can effectively manage test coverage with real-world devices. Why? Because they have testers spread in different markets and locations, where popular device manufacturers vary. These companies are also more likely to team up with networked testing partners that rely on contract testers and their combined thousands of real hardware devices. 

With easy access to the devices that matter to the product, distributed testers can more quickly satisfy device coverage requirements for a release. When testing isn’t distributed, an engineering manager will need to procure device coverage for important releases, and the time it takes to do so will slow shipping speeds considerably.

In so many ways, distributed testing makes shipping quality updates to your users faster. 

Challenges of Distributed Testing

In global distributed testing, test environment machines are located in different regions and locations. This causes challenges related to infrastructure, synchronization, and data management. 

Let’s take a look at the most common challenges that teams face in distributed testing:

1. Infrastructure management: Distributed test tools require more complex configurations and infrastructure. Setting up and maintaining this infrastructure can cause challenges, such as networking issues and scalability.
2. Synchronization: Running tests across multiple machines requires careful coordination. Tests should be synchronized to ensure they start, stop, and report results correctly across all nodes. Async tests can cause inconsistent results and false positives.
3. Data management: Distributed testing systems are configured to execute in parallel with different test data. Ensuring that all nodes have access to the necessary test data in real time can be challenging. 
4. Monitoring and logging: Collecting and aggregating logs from multiple nodes and ensuring that all logs are collected coherently can be challenging. 
5. Fault tolerance and recovery: Building a self-healing distributed testing system is complex. Testers need to ensure that if the master node fails during the test, the system can recover without halting the entire test. 
6. Cost management: Running distributed tests often requires more resources, such as hardware, cloud instances, or network infrastructure. Managing these costs, especially in the cloud, can become expensive over time.

Distributed Testing Tools

Distributed testing setups are complex, huge, and spread across multiple nodes. These setups cannot be created manually. It requires specific tools and expertise to set up an efficient and end-to-end distributed testing system.

Distributed testing tools ensure systems can handle global traffic and diverse environments. These tools simulate large-scale conditions, find weaknesses, and improve overall quality. 

Let’s explore some of the most powerful distributed testing tools:

1. Apache JMeter

Apache JMeter is an open-source tool for load and performance testing. It generates load across distributed machines to test the performance of web applications, APIs, and other services.

Apache JMeter Integrated HTML Report

Apache JMeter has the following key features:

• Uses a master-slave architecture for distributing the load across multiple machines.
• Supports various protocols like HTTP, FTP, TCP, etc.
• Offers real-time monitoring and result aggregation.
• Can easily be integrated with continuous integration and continuous deployment tools.

2. Selenium Grid

Selenium Grid is a distributed testing tool designed to run automated browser tests in parallel. It helps perform cross-browser testing efficiently and reduces overall execution time.

Selenium Grid

The following are the key features of Selenium Grid:

• Works on a hub-node architecture where the hub controls multiple nodes.
• Enables parallel test execution across different browsers.
• Supports various operating systems like Windows, macOS, and Linux.
• Ideal for the remote execution of tests on the cloud.

3. Locust

Locust is an open-source load-testing tool focused on distributed performance testing. It allows users to simulate large user traffic for web applications and APIs.

Locust Dashboard

The following key features distinguish Locust:

• Supports distributed load generation across multiple machines.
• Allows writing test scenarios in Python.
• Scales dynamically and can adjust the number of simulated users during tests.
• Efficiently handles high loads making it ideal for large-scale performance tests.

4. Taurus

Taurus is an open-source test automation framework that simplifies running distributed tests. It integrates smoothly with tools like JMeter, Selenium, and Gatling.

Taurus Dashboard

The following key features distinguish Taurus:

• Provides a simple YAML-based configuration for complex test scenarios.
• Offers real-time monitoring and reporting.
• Suitable for distributed cloud testing on AWS and Azure.
• Supports multiple testing tools within a single framework.

5. ChaosMonkey

ChaosMonkey is a famous chaos testing tool developed by Netflix. It intentionally causes random failures to test the resilience and recovery of distributed systems.

The following key features distinguish ChaosMonkey:

• Focuses on resilience testing and identifying weaknesses in systems.
• Works well with cloud environments like AWS.
• Builds self-healing tests to automatically handle random failures.
• Can be used with continuous testing to improve reliability.

Adopting Distributed Testing with Testlio

Testlio can fill the gap between in-house and distributed teams, connecting you with a global network of skilled testers. 

Here’s how Testlio can help you effectively adopt distributed testing:

• Global testing community: With Testlio, you can access a vast pool of testers from diverse backgrounds and locations. This diversity allows for real-time testing across different time zones and locations.

• Implement a master-slave architecture: Distributed testing systems can be complex to build. Testlio team can help you build a master-slave architecture to meet large-scale application demands. 

• Faster product delivery: Testlio teams are spread across the globe, with separate teams for day and night. Testing 24/7 can accelerate the testing process and help deliver products faster.

• Adopt continuous distributed testing practices: The Testlio team adopts continuous testing practices to ensure that testing is an ongoing activity rather than a one-off event. This ensures faster test execution in a continuous environment and identifies defects early.

To enhance your software’s performance, partner with Testlio for distributed testing. 

Contact sales to learn how our dedicated team will help you switch from localized to globally distributed testing.