The Value of Concurrent Testing


Concurrent testing is the concept that as software is being developed, it is also being tested. Concurrent testing can be done in several ways; one of the most common is to perform testing at the system level. As a development team completes coding requirements for an application or system, this required code becomes testable, while other team members can execute test cases against the completed code.


Personal experience within Agile testing using SCRUM, XP, Crystal, and other processes has revealed that concurrent testing can be incorporated to shorten the feedback loop to the Agile team. This helps solve issues within the Cost of Failure concept. Cost of Failure is defined as the concept that the longer you wait to get something fixed, the higher the price/cost to fix it. As the feedback loop is shortened, the cost of the defect/bug is reduced.



Here is a sample scenario where concurrent testing can add value.

Team Process Scenario


You are working in a software development company where Agile practices have been adopted; SCRUM is also used with the Agile team. The team consists of:

  • 4 developers
  • 1 QA Analyst
  • 1 GUI Tester
  • 1 Technical Writer

Average cost per team member is $72/hr, which includes energy costs, application hardware and software usage, etc.

Development Process Scenario

Currently in Iteration/SPRINT 3, the developer has:

  • Set up test cases (based on Test-Driven Development processes)
  • Created tasks
  • Executed the test cases and experienced failure
  • Developed solutions via software to ensure the tests pass
  • Senior Developer has reviewed code and agreed that coding has been done within Story guidelines (tasks completed, tests passing)

Testing Process Scenario

  • Tester is required to run test cases in a like-for-like system environment (virtual machines?)
  • Tester discovered 2 critical defects that the developer missed (negative tests were executed; not included in development Unit tests)
  • Tester and Developer worked on problem discovery and solutions, OR tester documented issues and moved on

Aftermath Scenario

  • 2 weeks later, all stories completed, review and retrospective done, planning for next SPRINT commences
  • Developer asks about Defect discovered in SPRINT-3; after 30-minute review with team, the Product Owner agrees that this is a major defect and requires a fix
  • After spending 5 minutes estimating scope of fix, QA Analyst works with tester to create test cases to validate the defect fixes (10 minutes)
  • Developer spends 15 minutes during SPRINT-4 reworking code, 5 minutes getting tests to pass, and returns tests to tester for final execution

Cost Comparisons

  • 8 team members in review for 35 minutes (280 minutes total)
  • QA Analyst and Tester rebuild test cases for defect (20 minutes total)
  • Developer re-work (20 minutes total)
  • 320 minutes X 72/Hr. = $381.60 for work during SPRINT-4
  • If re-work completed in SPRINT-3 = $48
  • ROI on concurrent testing when used with short feedback loop = 800%


Significant savings if defect discovery and solution performed in SPRINT-3; planning removed from equation and less man/hours required if fix completed in SPRINT-3.


Additional Solution Scenario

Work on a model where issues are brought up in Daily Stand-Up Meeting and determine if team should immediately schedule and work on fix. Typically, the idea can be adopted that if it takes less than 15 minutes to fix defect immediately, do it. Otherwise, document the issue and include it on Product Backlog for next iteration. This works well unless the defects begin to keep developers from daily work schedule for their tasks in the current iteration. This is a textbook example of scope creep, and team may not deliver finished product for iteration.

About the Author

Bob Small has 10 years in the IT industry. Bob has been a developer for a Professional Senior care provider. Bob started as a System Tester for the number one domain registrar in the world. Bob continued his career in testing and advanced into Quality Assurance at a leading contact center solution provider. Bob has recently started guest lecturing at local Universities and colleges. Bob has won worldwide online testing

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