February 10, 2023
min read

Continuous Testing in DevOps

Learn how to implement continuous testing in DevOps, including key components, the differences between traditional and continuous testing, and how continuous integration, continuous delivery, and continuous testing interact.

Continuous testing is the practice of automatically running frequent unit, integration, and regression tests throughout the software development life cycle (SDLC) to identify and fix defects as early as possible. It is different from regular testing in that it is an ongoing process rather than a one-time event, and it is sufficiently automated to allow for on-demand execution.

In this article, we will explain the importance of continuous testing in DevOps and how it helps teams ensure the quality and reliability of software.

Figure 1: Continuous testing is part of the continuous delivery process (source)

Summary of key continuous testing concepts in DevOps

Concept Description
Continuous testing A process of frequently and automatically running tests throughout the software development life cycle to identify and fix defects as early as possible
Traditional software testing An approach to testing where a quality assurance (QA) team conducts testing either manually or using scripts during a software development sprint
Continuous testing in DevOps Incorporating testing into the continuous integration and continuous delivery pipeline to guarantee that the developed software meets high standards
Test automation Using tools such as Selenium (scripted automation) and Appium (mobile testing) to remove the dependence on a human clicking on the UI to observe the results
Continuous integration Integrating code changes and service dependencies from multiple developers into a central repository using tools such as GitHub and automating the process with tools like Jenkins or CircleCI
Continuous delivery Automating the deployment of code changes to test and production environments using tools such as Jenkins or Spinnaker
Collaboration and communication tools Tools that enable developers and testers to collaborate effectively and share information about defects and testing progress
Testing environment An environment that mimics the production environment and workload and allows teams to test code changes under realistic conditions before deployment

Differences between traditional and continuous testing

Traditional software testing is the approach to testing where quality assurance is conducted at predetermined intervals during the development process, typically at the end of each iteration or release. It may include manual or automated testing tools.

Continuous testing is an approach that involves ongoing testing throughout the development process. It means that testing is conducted as code is written and changes are made, providing faster feedback on code quality. This approach includes a broader range of testing types—such as unit, functional, performance, security, and integration testing—to ensure that all aspects of the product are thoroughly tested.

The key differences between traditional and continuous software testing are the speed, frequency, and level of manual effort involved in testing. Continuous testing improves the overall quality of the product by identifying and fixing issues soon after developers have written the code, which is when the context is freshest in their minds.

Continuous testing framework and components

A continuous testing framework is a system that enables organizations to test their software continuously throughout the development process. It consists of several components that work together to ensure that the software is tested thoroughly and efficiently.

Figure 2: Components of continuous integration, of which testing is a crucial part (source)

As illustrated in the diagram above, we can divide the continuous integration process into five steps:

  1. Source control: This component is responsible for managing and tracking changes to the codebase, allowing developers to collaborate and work on the same codebase while ensuring that changes do not interfere with each other. Popular source control tools include open-source tools like Git and Subversion as well as paid services like GitHub and GitLab.
  2. Build: This component is responsible for compiling and packaging the codebase into a format that can be deployed and run in different environments. It typically includes tasks such as compiling code, creating executable files, and generating documentation. Examples of build tools include Jenkins, CircleCI, and Travis CI.
  3. Test: This component is responsible for running automated tests on the codebase to ensure that it meets the specified requirements and that any changes made do not introduce new bugs. This part of the process includes unit, integration, regression, and acceptance tests. It also includes provisioning infrastructure to create test environments that allow developers to test their code in a safe environment before releasing it to production. Examples of testing tools include JUnit, Playwright, and Selenium.
  4. Report: This component is responsible for generating reports based on test results, which includes key performance indicators (KPI)—such as the number of tests passed, failed, and skipped—as well as the time taken to run the tests. This function also provides detailed information on any test failures, including the error message and a stack trace. Examples of reporting tools include TestNG.
  5. Release: This component is responsible for deploying the code to production environments. It includes tasks such as provisioning resources, configuring environments, and deploying the code. Examples of release tools include Ansible, Terraform and Puppet.

Each of these components plays an important role in ensuring that the codebase is of high quality and that any changes made do not introduce new bugs. By incorporating these components into the development process, engineers can ensure that their code is thoroughly tested and ready for release to production.

CI vs. CD vs. CT

Continuous integration and continuous delivery are two important concepts in DevOps that are used to improve the speed and quality of software delivery. Here, we will explain the difference between these two concepts and how continuous testing fits into the overall process.

Continuous integration (CI)

CI is a best practice involving integrating multiple developers' code changes into a central repository using version control tools. This integration process is automated with continuous integration tools that help identify and resolve integration problems early in the development cycle, store and organize code dependencies, and automatically compile the code in preparation for execution.

Continuous delivery or deployment (CD)

Continuous delivery (CD) automates the deployment of code changes to test and production environments using infrastructure-as-code tools. Containerized applications are easier to deploy using solutions like Docker Compose, which can deploy multiple containers simultaneously with a single command.

Continuous testing (CT)

Continuous testing is a fundamental part of the continuous delivery (CD) process, which is why it’s not separately called out and the popular CI/CD acronym doesn’t include CT.

Continuous testing includes unit testing of individual code components and integrated testing of the complete application. Importantly, it also encompasses regression testing to ensure that changes in the current release haven’t adversely affected the functionality of the features in the previous release of the software.

CT also includes tests intended to evaluate the application’s security vulnerabilities. Test coverage is expressed as a percentage of the total code base tested, so 100% would mean testing the entire code base. This is an essential CT measurement because it highlights the risk of defects and security flaws going unnoticed in the uncovered parts of the application; the higher the percentage, the better.

Putting it all together

Once the code checked in by the developers is integrated along with its dependencies and compiled (CI), the application is deployed to a test environment (CD) and tested using automated scripts (CT) before it’s finally deployed to production (CD).

Here is a high-level summary of the steps involved in continuous testing in DevOps:

  1. Check code changes into the code repository using Git or GitHub.
  2. Use continuous integration tools like Jenkins or CircleCI to detect code changes and trigger a build automatically.
  3. Automatically deploy the build to the test environment using tools like Docker compose, Terraform, Ansible, Chef, and Puppet.
  4. Use test automation tools like Selenium, Appium, or Jenkins to run tests in the test environment.
  5. Deploy the code to the production environment, assuming it passes all of the tests.

Ephemeral vs. persistent test environments

Test environments are necessary for enabling continuous testing in the DevOps pipeline. They provide a controlled and consistent environment for running tests, ensuring that the software functions as expected before it is deployed to production.

A persistent test environment refers to a dedicated environment that is set up once, updated over time, and used repeatedly to test the software. It is usually used for regression testing to ensure that the software continues to function as expected after new code changes are made. A persistent environment doesn’t allow multiple streams of testing to happen simultaneously since the common resources are shared among all developers and testers. Another downside is the lack of isolation, which means that when a developer introduces a new bug that blocks the code from being compiled, it must be addressed before others can proceed with their testing.

An ephemeral test environment, also known as a preview environment, is a temporary test environment created for each feature branch. This approach allows for isolated testing of each new feature before it is integrated into the main branch, resulting in more efficient testing and faster feedback for developers.

Implementing and maintaining ephemeral platforms traditionally required a significant investment and was available only to large organizations with lots of time and deep pockets. Modern tools like Uffizzi streamline the process of deploying ephemeral environments for each feature branch, allowing for isolated testing of each new feature before it is integrated into the main code branch. If the tests pass, the code is automatically deployed to the production environment; if the tests fail, you can roll back the code and notify the developers of the failure.

Tools like Uffizzi can take advantage of the Docker Compose file to set up an entire application environment for the duration of the testing, including the database and backend services, tearing the environment down once the testing is completed.

By integrating testing into the CI/CD pipeline, continuous testing in DevOps allows for faster detection and resolution of defects, resulting in a higher-quality software product.

Continuous testing best practices

The following best practices will enable you to get the most from continuous testing:

  • Adopt a “shift-left” testing strategy by testing as early as possible in the development process. This approach helps identify and fix issues early on, reducing overall testing needs and avoiding costly rework once the application is fully integrated and deployed to production. (The term “left” refers to the left side of a typical software development life cycle diagram that unfolds from left to right; the left side represents the early part of the process, when architects design software and developers write code.)
  • Measure test coverage to ensure that all critical features are being tested. Tools such as JaCoCo, Istanbul, and Codecov can be used to measure test coverage and identify areas that need more testing.
  • Adopt test-driven development (TDD) to write automated tests before developing the code to ensure that it is written to pass the tests and meet product requirements.
  • Use a preview-as-a-service platform such as Uffizzi to provide fast, iterative testing and feedback to development teams.

Final thoughts on continuous testing in DevOps

Continuous testing is a crucial practice in DevOps that helps teams ensure the quality and reliability of software. By frequently and automatically running tests throughout the development life cycle, teams can quickly identify and fix problems, improve the speed and efficiency of the development process, and deliver high-quality software to users.

Continuous testing is different from regular testing, which is a one-time event that typically occurs at predetermined intervals during the development process. To implement continuous testing in DevOps, it's important to consider tools and processes such as test automation, continuous integration and delivery, collaboration and communication tools, and testing environments.

Uffizzi automates setting up and tearing down a test environment for each feature branch, dramatically improving developer productivity by maintaining isolated and ephemeral full-stack test environments integrated with a CI/CD pipeline. Uffizzi is available both in an open-source project and as an environment-as-a-service (EaaS) offering.

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