Shift left – defined

Shift left or shift left testing is the concept of performing quality assurance work as early as possible in the software development cycle to reduce the overall work required to deliver high quality software.

Even in Agile there is a sequence that is followed in software development which is typically as follows:

  1. Requirements
  2. Architecture
  3. Design
  4. Coding
  5. Release

It is has been found that the cost of fixing a defect increases 7-10 times as it moves from the stage in which it was created to the subsequent stage.  For example a requirements problem found within the requiremetns phase might cost $50 to fix, but it would cast $350-500 to fix once the architecture work had been done.   The rapid escalation of cost to fix bugs has been well reported in this blog post about Shift left testing:

In this article we will explore:

  1. Why are software requirements problems commonplace
  2. Why are they the most costly to fix
  3. How shift-left testing can fix them
  4. Why shift-left testing is one of the most valuable things you can do on a software project.