Pesticide Paradox in Software Testing

Pests and Bugs sound alike?? They act alike too!! 

Boris Beizer, in his book Software Testing Techniques (1990) coined the term pesticide paradox to describe the phenomenon that the more you test software, the more immune it becomes to your tests.

Just like, if you keep applying the same pesticide, the insects eventually build up resistance and the pesticide no longer works. Software undergoing the same repetitive tests build resistance to them, and they fail to catch more defects after that.

  • Software undergoing the same repetitive tests eventually builds up resistance to them.
  • As you run your tests multiple times, they stop being effective in catching bugs.
  • Moreover, part of the new defects introduced into the system will not be caught by your existing tests and will be released onto the field.

Solution: Refurnish and Revise Test Materials regularly

In order to overcome the pesticide paradox, testers must regularly develop newer tests exercising the various parts of the system and their inter-connections to find additional defects.

Also, testers cannot forever rely on existing test techniques or methods and must be on the look out to continually improve upon existing methods to make testing more effective.

It is suggested to keep revisiting the test cases regularly and revising them. Though agile teams provide little spare time for such activities, but the testing team is bound to keep planning these exercises within the team in order to keep the best performance coming. A few ideas to achieve this:

  • Brainstorming sessions – to think of more ideas around the same component testing
  • Buddy Reviews – New joinees to the team are encouraged to give their fresh perspective to the existing test scenarios for the product, which might get some new cases added.
  • Strike out older tests on functionalities that are changed / removed
  • Build new tests from scratch if a major change is made in a component – to open a fresh perspective

 

UPDATE–

This article has been recommended and used as a reference by HANNES LINDBLOM in his blog at https://konsultbolag1.se/bloggen/veckans-testartips-15-tur-genom-variation

 

 

Automation Test Suites Are Not God! 

Earlier this year, one of my articles was published at http://www.agileconnection.com , wherin I highlighted the role and use of automation in an agile context and the irreplaceable importance of manual testing.

Here are excerpts from my article – for the complete text , visit 

http://www.agileconnection.com/article/automation-test-suites-are-not-god 

          Automation Test Suites Are Not God!

Working in an agile environment makes it essential to automate system testing to rerun tests in each iteration. But in the nascent stages of some systems, there are changes in the UI, product flow, or design itself in each iteration, making it difficult to maintain the automation scripts. The role of automation in agile context is repetition of regression and redundant tasks, while the actual testing happens at the hands of manual testers. The creativity, skills, experience, and analytical thought process of a human mind cannot be replaced by automated scripts. This belief has to be ingrained in every organization’s culture in order to achieve the best quality.

Talking about software testing today is incomplete without the mention of test automation. Automation has become an important part of testing tasks and is deemed critical to the success of any software development team—and rightly so, with all its benefits like speed, reliability, reducing redundancy, and ensuring complete regression cycles within tight deadlines.

But the common perception of team managers and policy makers is that automation tools are the complete package for testing activities, and they begin expecting the world out of them. A common misconception is that test automation is the “silver bullet” for improving quality, and organizations start to believe that investing once in an automation tool ends all other testing-related tasks and investments. Managers start expecting everything out of their automation suites—100 percent coverage, minimum run times, no maintenance, and quality delivered overnight. It’s basically expecting godlike miracles to happen! Hence, there arises a need to educate and understand the actual purpose of automation and the importance of manual tests in this context.

Working in an agile environment makes it essential to automate system testing due to the bulk of regression tests required in every iteration. But what makes test automation hard within an agile context is its very inherent nature of constant change. Because the system under test changes continuously, the automation scripts have to be changed so often that they actually become a task themselves instead of a benefit.

As tester James Bach wrote, Test Automation Rule #1 is “A good manual test cannot be automated.” According to this thought, it is certainly possible to create a powerful and useful automated test, which will help you know where to look and to use your manual exploration. But the maximum benefit thereafter will come out of using the experience and exploration techniques.

This is based on the fact that humans have the ability to notice, analyze, and observe things that computers cannot. Even for unskilled testers, for amateur minds, or in total absence of any knowledge, requirements, or specifications of the system under test, people can observe and find a lot of things no tool will be able to.

In a true sense, automation is not actually testing; it is merely the repetition of the tasks and tests that have been performed earlier and are only required as a part of regression cycles. Automation is made powerful by the various reports and metrics associated with it.

But the actual testing still happens at the hands of a real tester, who applies his creativity, skills, experience, and analytics to find and report bugs in the system under test. Once his tests pass, they are then converted to automated suites for the next iteration, and so on.

So the basic job of automation suites is to free up the time and resources of the manual testers from the repetitive and redundant tasks so that they are able to concentrate and focus on the new features delivered and find maximum bugs in those areas.

Therefore, it is very important to not get caught up in the various charts, coverage, and metrics of our test suites. Instead we must focus on our projects’ context and requirements and, based on those designs, our automated versus manual tests ratio.

A simple example to illustrate it would be testing a web form with multiple inputs and spreading across multiple pages. An automation script created for it would ideally open the webpage, input the values and then submit them, and maybe check a couple of validations on input fields along the way. So, the process would ideally be

Observe > Compare > Report

The automation should perform the mostly happy path of a user scenario, observe the behavior as per the set expected results, and inform whether the form passes or fails at the end.

On the other hand, if we perform manual tests on the same web form, we should try to enter the inputs in a different order; navigating to and from the pages and observing whether the inputs are retained or not; and looking for usability issues such as difficulty in locating the fields and navigating buttons, the font being too small or not clear in some setting, or form submission taking so long that some performance benchmarking might be required.

Perform > Analyze > Compare (with existing system, specifications, experience, discussions) >

> Inform (and discuss) > Recheck (if needed) >

> Personal Opinion and Suggestions > Final Report.

It shows that though the web form could have been easily tested by the automation test suite and been passed by it, we might miss out on other valuable aspects if we skip the manual and experience-based tests.

Markus Gartner, author of the book ATDD by Example, summed it up nicely when he wrote, “While automated tests focus on codifying knowledge we have today, exploratory testing helps us discover and understand stuff we might need tomorrow.” 

Automation test suites, though essential, should not be thought of as the “silver bullet” of quality. The actual test efforts still lie with the manual tester’s expertise and skills, without which actual quality cannot be ingrained into the system. We must keep a check on the unrealistic expectations for automation tests, because after all, automation suites are not God!

Dear Testers and Agile Enthusiasts – Welcome!

Dear Testers and Agile Enthusiasts

I am a full-time software tester, a zealous and passionate one at that! With almost 7 years of experience working in Agile environment, I have a lot to share and talk about regarding its various aspects. So I am excited about my new found passion in writing about topics of interest in the industry.

As of now, my articles have featured at InnovateQA.com, and Techwell community’s AgileConnection.com and Stickyminds.com. But I figured I needed a space of my own to keep putting across new topics and ideas and open them for discussion with fellow enthusiastic professionals, hence this blog!

I shall endevour to bring the most relevant and the best topics of the agile and testing community for you.

Thanks and Welcome!

Nishi 🙂