Shift Left Approach and Integration Testing

In an Agile environment, software development teams are expected to work more quickly, cutting down on delivery time while maintaining the high quality of each release. They are also under more pressure than ever to cut testing costs.

To meet the rising demand for high-quality software in a shorter amount of time, the software testing landscape has undergone a significant transformation. The Waterfall Model has historically been used to test software applications. Yet, the industry is now searching for alternatives. Why so? There is a need to maintain release cycles as short as possible. Shift left testing, sometimes also spelled as shift-left testing, is one of these remedies.

What is shift left? This article will define shift left testing, explaining why to use it, how to put it into practice, its advantages and four types.

In a traditional Waterfall model, testing comes into play at the pipeline’s very end (or very right). What is shifting left in this context? Shifting left meaning refers to the process of pushing testing to the “left” or earlier stages of the pipeline. As shift left definition suggests, defects are found and fixed as early in the software development process as possible.

Shifting testing to the left enhances software quality and cuts down on time spent later in the pipeline troubleshooting problems, which typically get worse as development moves forward. Essentially, this means that software engineers do additional shift left tests before they push their code units to version control. To help QA shift left to succeed and advance more robust products, every engineer should run several tests.

As the agile methodology describes, we frequently need to pay more attention to the benefits of testing early in the software development life cycle (SDLC). It’s crucial first to comprehend how bugs get into the code. Regular code testing for every code increment ensures the project’s quality and saves you time and money.

Any bugs that do appear when testing is on hold until the end of development are typically more challenging to address. How to address this problem? The only solution is to entirely redesign the product because all the code is already there. This approach results in increased software development costs and a longer time to market.

Shift left testing principles let software engineers find bugs quickly at earlier stages of software development. The most manageable bugs to resolve are those found when engineers write or review code, since these code units are short and much easier to manage. Thus, test the code before it gets to the main development branch. Otherwise, the time and effort needed to identify errors increases once it is done.

So, what does shift left mean for your business? The reasons to adopt shift left testing define the advantages of this testing approach. Shift left testing benefits include:

Shift left testing in Agile calls for software engineers to test and QA specialists to code. The merged code is cleaner and less prone to errors when developers test their code before submitting it to the main branch. Individual code units are easier to check because they are smaller and easy to explore.

Let’s look at the testing pyramid for more insight into implementing the shift left approach. It implies that 70–80 percent of tests happen at the early stages of the SDLC in local and branch environments. These are mainly unit and integration tests.

The goals of shifting left approach are the following:

When implementing the shift left testing approach, a team may face particular difficulties. It is essential to consider the following issues:

To benefit from the shift left development and testing approach, it is essential to know what challenges a shift left QA team may encounter. Following the practices listed below will help you avoid the possible pitfalls of shift left testing implementation.

To move testing to the left, testers might use four essentially different methods. The variations of the conventional V model are used to clarify each of these four approaches in this section.

First of all, let’s look at the traditional V model. It is a classic graphical representation of software engineering activities. The left side of the V stands for the requirements, architecture, design, and implementation, while the right side is for integration and testing.

You can easily take the V model for a strict sequential waterfall development cycle. Thus, it may seem incompatible with modern evolutionary development in projects that use Agile or DevOps approaches. No wonder it has come under significant and justified criticism in recent decades.

Instead, the V model offers a condensed manner to explain our discussions of approaches to shift left testing. Thus, this concept is useful as long as system and software engineers keep in mind its limits and see it as hypothetical. Shifting to the left on the V means moving testing to the left.

On the right side of the V, the typical shift left moves the testing attention down and to the left. Traditional shift left focuses more on the unit and integration testing than acceptability and system-level testing, such as UI testing with record and playback tools (e.g., API testing and modern test tools). The changeover to shift left testing has largely been accomplished.

Numerous products that create hugely complicated software-dependent systems divide the development process into shorter-duration increments (Vs). The gray areas of the single, large waterfall V model’s types of testing move left. Thus, they become increments of the equivalent types of testing in the smaller incremental V models. The dashed red arrows represent this shift left.

Incremental shift left testing moves operational and developmental testing to the left, when each increment also serves as a delivery to the client and operations. When constructing large, complicated systems (especially those that incorporate a significant amount of hardware) incremental shift left testing is common. The changeover to incremental shift left has also been largely finished, just as the traditional shift left.

Instead of a single or a limited number of Vs (like in the two examples of shift left testing above), agile and DevOps projects include several short-duration Vs (also known as sprints). These minor Vs would also change if the core requirements and architecture got blocked during one or more early sprints, or if test-first and test-driven development (TDD) were to be implemented.

Why the shift to the left then? It happens because the right-side testing types of the oldest of these small Vs are to the left of the right-side testing types of the larger V(s) they replace.

Although Agile and DevOps look strikingly similar graphically, Agile testing is often limited to developmental testing. It excludes operational testing, which takes place after the system gets into service. The change to Agile/DevOps shift left testing is currently widespread and ongoing

Prior types of shifting testing focused on starting software testing earlier in the development cycle. Model testing, which tests executable requirements, architecture, and design models, shifts testing to the left side of the V.

Instead of waiting a long time (traditional), a medium time (incremental), or a short time (Agile/DevOps) until software on the right side of the Vs is accessible for testing, this shift enables testing to start almost immediately. This trend will pick up steam as more executable models and related simulation/testing tools become accessible.

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