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Shift Left Testing (What It Is & How To Do It)

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Myra Nizami
Myra Nizami
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Wondering about shift left testing? We explain what shift left testing is, how it relates to DevOps and SRE, why it’s done, and how to get started.

What is shift left testing?

Shift left testing refers to the technique of testing earlier in the software development lifecycle. The goals are to identify and correct defects in the software requirements and design early in the process. 

Before we dive into why shifting left in DevOps and SRE benefits teams, there are some important clarifications to make. You’ll often hear about shift right vs. shift left, with some debate about the terms. Shift left and shift right are complementary terms. Shift left refers to starting tests earlier in the development process, and shift right refers to testing later in the cycle in the production environment. When we talk about shift left vs. shift right, shift left focuses on testing for quality while shift right tests for undefined, unknown, or unexpected behavior. 

Shift left in DevOps is crucial since it advocates for testing early and often. In a DevOps pipeline, shift left testing is integrated closer to the start of the lifecycle in order to identify problems and issues earlier in the development cycle. 

Benefits of shift left testing

Shift left is crucial because it brings more reliability and quality earlier in the development process. In the past, development and quality assurance (QA) would work separately, organized by a base level structure. The result was a lot of back-and-forth between development and QA teams, slow work, and delays in fixing bugs. Code was already mostly completed before QA got their hands on it, requiring major redesigns if significant bugs were found.

And that’s precisely where shift lift testing fits in. As the software development industry has evolved, it’s become abundantly clear that it’s in everyone’s best interest to spot bugs earlier in the process rather than later. So, with a greater focus on the customer experience, shift left testing has come into focus as another way for teams to operate.

Shift left testing focuses on testing often and adds automation to test more frequently without adding manual testing time. For teams that adopt shift left testing, they see serious benefits. It enables faster detection of bugs instead of letting issues continue down the development pipeline and reach customers. The purpose of shift left testing is to detect issues and undertake continuous integration and testing before releasing the software into the production environment. It enables better visibility and control. 

Otherwise, teams may not have the resources to do major overhauls if testing is left too far down the process, and debugging will become more complex as software continues to be integrated. Shift left testing enables teams to get ahead of issues and be more proactive earlier in the development process. 

Methods for shift left testing

There are four methods that teams can undertake to start shift left testing:

  1. Traditional shift left testing: Traditional shift left testing focuses on unit and integration testing. 
  2. Incremental shift left testing: For the waterfall model type of development where larger projects are broken down into smaller increments, incremental testing tests each time development progresses. 
  3. Agile/DevOps Shift Left Testing: For teams that use sprints as part of the development process, shift left testing is modified according to the sprint process, focusing on basic requirements and architecture to get a project out as efficiently as possible.
  4. Model-Based Shift Left Testing: Model-based testing is used to test requirements, architecture, and design models as soon as they are executable, rather than waiting for completion. As soon as the most simple version of a model that has the required functionality is completed, it can be tested.

Shift left in DevOps goes beyond simple QA testing and instead follows an adaptive continuous testing model as development occurs. Implementing shift left testing is about first developing an understanding of how teams operate, identifying early vulnerability prioritization, and deciding what kind of shift left testing will help uncover the issues being prioritized. 

Teams can use behavior-driven development, where operations and developers collaborate to determine the intended behavior of projects to build the tests required to ensure that behavior.  This part of the process is essentially around developing a unified test strategy that looks at the bigger picture for what is needed to deliver the best product possible to customers. 

Implementing shift left testing

Once there is a general idea in place, teams need to consider how much shift left testing can be automated and at what part of the development process will automation be most beneficial.

The next step is demand planning to implement the measures, including looking at the budget, resourcing, and the testing and tools that have been identified as necessary for shift left testing. 

Static testing measures will also need to be implemented, including validating requirements and design using checklists and log defects. Risk-based analysis will also need to be included for each test scenario to understand the likelihood of failure and its impact. Aiming for code that passes every test 100% of the time might be unfeasible or not worth the effort. Use SLOs set to where users experience inconvenience to understand what an acceptable test result is.

Another critical consideration is the tools needed for shift left testing. Each team will have different requirements and levels of involvement. Automated testing tools like Jenkins will need to be combined with other types of tools, such as defect tracking and source control management, to create a comprehensive testing strategy. 

How can Blameless help? 

As more teams adopt shift left testing, they need SRE to make the most of their testing results. Shift left in DevOps enables SREs to become partners in the development process and creates opportunities to build resilient and reliable systems. 

With Blameless, teams have the necessary tools for detecting issues early on, including incident resolution, automated runbooks, reliability insights, and other features such as incident retrospectives to help teams spot issues faster and work towards a blameless culture. You can learn more about how Blameless can help teams shift left by requesting a demo or signing up for the newsletter to gain more insight delivered straight to your inbox. 

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