Shift Left – What does it mean?

A traditional software testing approach can often result in bugs being discovered late in the Software Development Life Cycle (SDLC), i.e. just before the scheduled release. There are a number of downsides to this, the most common being that any delay in resolving these issues may translate into a delayed release.

Agile practices call for faster, earlier, and continuous testing practices to reduce the feedback cycle and allow shorter development cycles (sprints) to occur.

When we think of the SDLC laid out in a line from left to right, as below, then it becomes easier to understand the term ‘Shift Left’ as pushing the test activities towards the left hand (start) of this line.

In practical terms, when a company adopts the mantra of ‘shifting left’, they are pushing their software delivery practices to consider testing from the very inception of a project.

Involving specialist and experienced test personnel from the strategy level discussion phase allows the team to iron out any potential issues before they become ‘baked in’ through the design and development phases.

When testing isn’t undertaken until the end of development, any defects uncovered will usually be more difficult and time-consuming to fix. In extreme cases, the resolution may even require an architectural rework, when this is not possible it would result in the business accepting a sub-optimal product experience for their users.

There have been many studies conducted that show the rapidly escalating costs of defect resolution relative to the phase in which they are discovered. This has become a universally accepted truth in the world of Software Delivery.

Simply put, the earlier you catch a bug, the cheaper it will be to fix, and with some estimates indicating that over half of all software defects could be identified during the requirements phase, and with less than 10% emerging during the development phase of the lifecycle, there are plenty of opportunities to capitalise by adopting a shift left approach.

The following graph courtesy of NIST helps to visualise how the effort in detecting and fixing defects increases as the software moves through phases of software development.

The Shift Left testing approach highlights the need for the team to concentrate on software build integrity from the earliest stage of design and development.

Shifting left enables bugs to be identified as the code is being created. These bugs are the easiest to fix because the code units are small and infinitely more manageable.

Here are some of the most important benefits which can be obtained by adopting a shift left strategy:

Pushing your test automation activities further left up the cycle gives a faster feedback loop and allows for a much more stable framework to be established than is possible with UI automation alone. Maintenance overheads are reduced and results are available quickly.

When you find defects earlier in the production cycle, you can fix them a lot faster, as a result:

• The time between releases can reduce.
• The quality of software improves exponentially as the development cycles continue.

Shifting left allows Project teams to spend less time fixing critical or showstopper bugs that may have arisen and allows them to focus early on areas like security, performance, or usability requirements that can often be overlooked. Leading to higher customer satisfaction rates and potentially increased revenue for the company.

If you want to enable your Software Delivery teams to increase their velocity and quality whilst reducing bugs (and staff churn) then it’s time to shift left!

If you need a hand with implementing this approach on your project, we would love to help. You can reach out to our test experts at [email protected] for a casual discussion about your challenges.