Which of the following is an example of a "shift left" testing strategy?

The concept of "shift left" in DevOps refers to moving quality assurance and security testing activities earlier into the software development lifecycle, closer to the initial development phase. Unit testing integrated into a Continuous Integration (CI) pipeline executes automated tests every time developers commit code, catching bugs immediately at the earliest possible stage. This early feedback reduces the cost and effort of defect remediation compared to discovering issues late in testing or production environments. Options A and D take place late in the deployment cycle or post-release, while option B describes a manual method that does not inherently shift testing left into early automated pipelines.

A. Testing in production occurs at the absolute right end of the deployment pipeline, making it the opposite of a shift-left testing strategy.
B. Manual testing is often slow and performed later in the development cycle, whereas shifting left relies on early automated testing practices.
D. Biannual vulnerability assessments of live systems are periodic late-stage checks performed long after code release, far to the right of initial development.

IEEE Standard for Software and Systems Engineering—Software Testing—Part 1: Concepts and Definitions (ISO/IEC/IEEE 29119-1:2022). DOI: 10.1109/IEEESTD.2022.9687258

Kim, G., Humble, J., Debois, P., & Willis, J. (2016). The DevOps Handbook. IT Revolution Press. Chapter 10: Enable Automated Testing, pp. 125–134.