Smart checklists make you think

The power of checklists in other disciplines

In other mature disciplines like medicine, aviation, construction where the impact of simple defects is enormous, it is smart checklists that have come to the rescue and saved millions of dollars and saved many lives.

The Checklist Manifesto  by Atul Gawande, a surgeon, extols the power of checklist. He states that any problem can be categorised into simple, complex and complicated, and how the smart checklists can solve these.

‘Simple’ problems are those that are individualistic in nature with a set of stuff to be done, while ‘Complicated’ problems implies multiple teams/people coordination/timing issues, and ‘Complex’ problem is where outcomes are different despite same application.

Checklists are not mindless compliance

Smart checklists are not about mindless compliance, not about ticking boxes, it is really about tickling the brain to think better and ensure fault-proofing rapidly. In our industry, checklists have been seen a cheap brainless activity that is about ticking the checkboxes, and therefore presumed to be useless.

Smart checklists make you think

To solve complex problems, “push the power of decision making from a central authority to the periphery, allowing people to make decision and take responsibility”  (Atul Gawande).

The checklist needs to allow for judgement to be used in the tasks rather than enforce compliance, so that actions may be taken responsibly. Hence, a smart checklist is about enabling your thinking process by having:

  • Set of checks to ensure stupid but critical stuff is not overlooked
  • Set of checks to ensure coordination
  • To enable responsible actions to be taken without having to ask for authority.

Good checklists are precise and easy to use in most difficult situations, it does not spell out everything, but provides reminders of critical & important steps that even highly skilled professionals would miss.

Checklists seem to defend everyone, a kind cognitive net designed to catch flaws of memory and attention, a well designed checklist enables one to DO well, SYNC with others well, and take appropriate ACTions as needed. [5]

“The power of checklists is limited, they help experts remember how to manage a complex process or machine, make priorities clearer and prompt people to function well as a team.  By themselves, however, checklists cannot make anyone follow them.” [Boorman, Boeing]

We use checklists too, but are we effective?

Do we use checklists for early tests like DevTest? Yes, we do. But from what I have seen of numerous checklists like code review/UI checklists , it is more often is used like a compliance assessment, of ticking away a long list of items-to-check for. So this turns to be a mindless job and suffers poor implementation, as it is most ill suited for smart validation.

Smart checklist enables developing clean code

So should we really do dev test? Should we not become sensitive and write cleaner code? Well lean thinking (aka Agile) is of producing less bugs in the first place, not about testing more.

A ‘Smart DevChecklist’ enables one  to precisely accomplish this, to become more sensitive and written code that certainly does L1 through L4 issues. Remember, this is the most cost effective method to good quality. Well, a Smart DevChecklist is an efficient complement to dev test enabling an easy and efficient method to producing great code.

If you are keen to try out a SmartDevChecklist to rapidly do DevTest without the pain of dev test, it is available as part of the e-book listed alongside.


What is expected of code quality from developers?

Unit testing? Dev testing is a better term

The definition of what an unit is most often unclear and therefore unit testing more misunderstood. Martin Fowler in his blog Unit Test  states “It’s very ill-defined, and I see confusion can often occur when people think that it’s more tightly defined than it actually is “.

So let us use the term “Dev test” to state the early validation by developers during the development of code. What is expected of the code quality from developers? What should dev test uncover?  To setup a clear objective of what dev test should accomplish (objective), let us take a goal focused approach of as to what types of defects should be  uncovered at dev test.

“Quality Levels” – Defect types matter

Purposeful testing is about hypothesising potential type of defects and going after them.

Of course, as we one engages in this activity in the scientific manner, we revise and fine tune what to go after and how to go after.

Characterising the system under test as containing a “mixture” of various defect types, and inspired by fractional distillation as an efficient method of separation, Hypothesis-Based Immersive Session Testing (HyBIST)  sets up NINE quality levels of which the first FOUR are certain candidates for dev testing.

So what are the quality levels and  what is the purpose of tests at those levels?

Dev testing – What is the objective?

The objective of dev testing is that the building blocks of a system i.e. structural components are indeed clean enough to deliver the basic feature and worthy of integration to form the larger system. This means that a building block is internally   robust (structurally clean) and behaviourally correct (externally clean).

HBT Quality Levels

L1: Ensure bad inputs are rejected, about data types, values, boundaries
L2: Ensure that input interface is clean, about syntax(format), order, messages
L3: Ensure that internal structure is robust, about exception, resource handling, timing/sync, loops/iteration
L4: Ensure behaviour of feature is fine, about the business logic of the base technical feature
L5: Ensure behaviour of requirement/flow is fine, about the business logic of the requirement/flow that is a collection of technical features
L6: Ensure system works well is all different external environments and does not affect the environment
L7: Ensure that  key requirement/flow satisfies the expected attributes (e.g performance, volume…)
L8: Ensure that  final system deploys well in the real environment. Installation, configuration, migration are of interest here.
L9: Done by end users, the intention is ensure that it satisfies the actual end user’s intended needs and expectations.

So, what levels matter to the developer?

Quality levels denote a progression of quality as software is built. So as a developer, it is necessary to validate that basic behaviour of the building blocks that we build/modify. This means that a developer performs tests to ensure Levels 1-4 are satisfied, implying that the component is clean enough to integrate into the larger system. Additionally, if the component is critical to certain system attributes, then higher level tests beyond L5 could be useful to do.

DevTest need not be hard or painful, we have made it so. Oh, just automating unit tests does not help, well it is additional work, is it always needed? . The e-book below outlines a practical implementation of this and gives you a SmartDevChecklist as an aid to very rapidly perform DevTest. 


design checklist-fi

Design checklists to “Do, Sync & Act”

This article is the second one on checklists, the first one being “The power of checklist

Checklists seem to defend everyone, a kind cognitive net designed to catch flaws of memory and attention.

Atul Gawande in his book “ The Checklist Manifesto” states that there are three kinds of problems in the world:

  1. SIMPLE: Individualistic in nature, solvable by application of simple techniques.e.g. Bake a cake.
  2. COMPLICATED: Can be broken into a set of simple problems, requires multiple people, often multiple specialized teams. Timing, coordination becomes a serious concern. e.g. Launching a rocket.
  3. COMPLEX: These are problems where the solution applied to two similar problems may not result in the same outcomes. e.g. Raising a child. Expertise is valuable, but most certainly not sufficient.

He continues on to say that checklists can provide protection against elementary errors in the case of simple problems that we are designed with. This can be accomplished by simple activity task checklist.

In the case of complex problems that require multiple specialists to coordinate and be in sync, a simple activity task checklist won’t do, what is needed is a checklist with communication tasks to ensure that experts discuss on the matter jointly and take appropriate action.

“Man is fallible, but maybe men are less so” Belief in the wisdom of the group, the wisdom that multiple parts of eyes are on the problem and letting watchers decide what to do.

So how can checklists help in solving simple/complex problems? Using simple activity task checklists to ensure simple steps are not missed or skipped and checklist with communication tasks to ensure that everyone talks though and resolves hard and unexpected problems.

Building tall buildings is a complex problem and the success rate of the construction industry’s checklist process has been astonishing. Building failure is less than 0.00002%, where building failure is defined as the partial or full collapse of a functioning structure. (from a sample size of a few million buildings!).

Now let us turn our attention to the complex problem. How does one deal with complex, non-routine problems that are fundamentally difficult, potentially dangerous and unanticipated? In these situations, the knowledge required exceeds that of any individual and unpredictability reigns. To solve these it is necessary to push the power of decision making from a central authority to the periphery, allowing people to make the decision and take responsibility.

So the checklist needs to allow for judgment to be used in the tasks rather than enforce compliance, so that actions may be taken responsibly. This needs to have set of checks to ensure stupid but critical stuff is not overlooked, a set of checks to ensure coordination and enable responsible actions to be taken without having to ask for authority. There must be room for judgment, but judgment aided and even enhanced by a procedure. Note that in COMPLEX situations, checklists not only help, they are *required* for success.

So, how does one make checklists that work? Aviation industry thrives on checklists in normal times and also to tackle emergencies. The advice from Boorman from the “The Checklist Factory” of Boeing for making checklists that work are:

  1. Good checklists are precise, easy to use in the most difficult situations. They do not spell out everything, they only provide reminders of critical and important steps, the ones that even the highly skilled professionals would miss.
  2. Bad checklists are too long, hard to use; they are impractical. They treat people as dumb and try to spell out every step. So they turn people’s brain off rather than turning them on.

“The power of checklists is limited, they help experts remember how to manage a complex process or machine, make priorities clearer and prompt people to function well as a team. By themselves, however, checklists cannot make anyone follow them.” (Boorman, Boeing)

So how should a good checklist look like?

  1. Keep the length of checklist between five to nine items, the limit of human memory.
  2. Decide on whether you need a DO-CONFIRM checklist or READ-DO checklist. With a DO-CONFIRM checklist, individuals perform jobs from memory and experience and pause to CONFIRM that everything that was supposed to be done was done. With the READ-DO checklist, individuals carry out the tasks as they tick them off, it is like a recipe. So choose the right type of checklist for the situation. DO-CONFIRM gives a people a greater flexibility in performing the tasks while nonetheless having to stop and confirm at key points.
  3. Define clear pause points at which a checklist should be used
  4. The look of checklist matters, they should be free of clutter and fit into a page

In summary

  • Ticking boxes is not the ultimate goal
  • Checklist is not a formula, it enables one to be smart as possible
  • It improves outcomes with no increase in skill
  • Checklists aid efficient working

As smart individuals, we don’t like checklists. It somehow feels beneath us to use a checklist, an embarrassment. The fear is that checklists are about mindless adherence to protocol.

Hey, the checklist should get the dumb stuff out the way so as to let you focus on the hard stuff. We are all plagued by failures – by missed subtleties, overlooked knowledge, and outright errors. Just working harder won’t cut. Accept the fallibilities. Recognise the simplicity and power of the checklist.

Try a checklist. It works.

If you find the article interesting, please ‘like’, ‘share’ or leave a comment below.


The power of checklist

Recently I read the book “The Checklist Manifesto” by Atul Gawande. 

“An essential primer on complexity in medicine” is what New York Times states about his book whilst The Hindu states this as “An unusual exploration of the power of to-do list”.

As an individual committed to perfection, in constant search of scientific and smart ways to test/prevent and as an architect of Hypothesis Based Testing, I was spellbound reading this brilliantly written book that made the lowly checklist the kingpin, to tackle complexity and establish a standard for higher baseline performance.

The problem of extreme complexity The field of medicine has become the art of managing extreme complexity. It is a test whether such complexity can be humanly mastered: 13000+ diseases, syndromes and types of injury (13000 ways a body can fail), 6000 drugs, 4000 medicines and surgical procedures each with different requirements, risks and considerations. Phew, a lot to get right.

So what has been done to handle this? Split up knowledge into various specializations, in fact, we have super specialization today. But it is not just the breadth and quantity of knowledge that has made medicine complicated, it is also the execution of these. In an ICU, an average patient required 178 individual interactions per day!

So to save a desperately sick patient it is necessary to: (1) Get the knowledge right (2) Do the 178 daily tasks right.

Let us look at some facts: 50M operations/year, 150K deaths following surgery/year (this is 3x #road-fatalities), at least half of these avoidable. Knowledge exists in supremely specialized doctors, but mistakes occur.

So what do you when specialists fail? Well, the answer to this comes from an unexpected source, nothing to do with medicine.

The answer is: THE CHECKLIST

On Oct 30, 1985, a massive plane that carries 5x more bombs roared and lifted off from the airport in Dayton, Ohio and then crashed. The reason cited was “Pilot error”. A newspaper reported, “this was too much airplane for one man to fly”. Boeing the maker of this plane nearly went bankrupt.

So, how did they fix this issue? By creating a pilot’s checklist, as flying a new plane was too complicated to be left to the memory of any one person, however expert. The result: 1.8 million miles without one accident!

In a complex environment, experts are against two main difficulties: (1) Fallibility of human memory, especially when it comes to mundane/routine matters which are easily overlooked when you are strained to look at other pressing matters of hand (2) Skipping steps even when you remember them, as we know that certain steps in a complex process don’t matter.

Checklists seem to provide against such failures and instill a kind of discipline of higher performance.

Peter Provonost in 2001 decided to give a doctor’s checklist a try to tackle central line infections in ICU. So what was the result after one year of usage? Checklist prevented 43 infections and 8 deaths and saved USD 2M! In another experiment, it was noticed that patients not receiving recommended care dipped from 70% to 4% and pneumonia fell by a quarter and 21 fewer parents died.

In a bigger implementation titled the “Keystone Initiative” (2006) involving more hospitals of 18-month duration, the results were stunning- USD 17M saved, 1500+ lives saved!


So where am I heading? As a Test Practitioner, I am always amazed at how we behave like cowboys and miss simple issues causing great consternation to the customer and users. Here again, it is not about lack of knowledge, it is more often about carelessness. Some of the issues are so silly, that they can be prevented by the developer while coding, and certainly does not demand to test by a professional. This is where a checklist turns out to be very useful.

In an engagement with a product company, I noticed that one of the products has a product backlog of ~1000 issues found both internally and by the customer. Doing HyBIST level-wise analysis, we found that ~50% of the issues could have been caught/prevented by the developer preventing the vicious cycle of fix and re-test. A simple checklist used in a disciplined manner can fix this.

So how did the checklists help in the field of medicine or aviation? They helped in memory recall of clearly set out minimum necessary steps of the process. They established a standard for higher baseline performance.


So how can test practitioners become smarter to deliver more with less? One way is to instill discipline and deliver baseline performance. I am sure we all use some checklist or other but still find results a little short.

So how can I make an effective checklist and see a higher performance ? Especially in this rapid Agile Software world?

This will be the focus of my second part of this article to follow. Checklists can be used in many areas of software testing, I will focus in my next article on ‘How to prevent simple issues that plague developers making the tester a sacrificial goat for customer ire by using a simple “shall we say unit testing checklist”.

Related article: Design checklists to “Do, Sync & Act”

If you find the article interesting, please ‘like’, ‘share’ or leave a comment below.

Setting a new paradigm in Software Testing

Below is the article that was published in October 2011 issue online edition of The SmartTechie.

Although software testing has undergone significant progress in recent years, organizations have been demanding something new. Global market pressures are pushing organizations to get more for less. Innovation is not just for the principals, and they expect the same from their QA partners too. “The typical activity-based testing model has overworked itself too long. What the industry needed was a scientific approach” explains T Ashok, CEO of STAG Software, a boutique test engineering company headquartered in Bangalore. STAG is the pioneer of a scientific approach to testing – Hypothesis-Based Immersive Session Testing (HyBIST).

“Today, there is severe pressure on the captives to cut costs and over the years HyBIST has proven itself to significantly cut costs” says Ashok. In addition to standard offerings like outsourced QA, functional test automation, performance assessment, etc., STAG works with various organizations to deploy HyBIST. “STAG engages with its clients and restructures the entire approach of testing. The fundamental change has to come from the way a QA professional thinks and approaches a problem,” explains Ashok. While traditionally, the process is put together and people are forced to comply it, STAG’s approach differs. It leverages the organization’s available intellect first, before installing the process. A consultant typically engages with client over a period of three to six months where the testing team is made to unlearn the old techniques and start looking at the problems with a logical bent of mind, and then the process is set. The company has also licensed its methodology to the system integrators and service oriented companies.

Apart from deploying HyBIST in organizations, this year STAG is looking forward to release the HyBIST toolkit being developed over the last couple of years. The tool acts as a coach for a test professional and provides ‘guidance’ to test the right way.

Ashok feels that there is a much larger picture which needs addressing “It is not just the IT companies that need a change in approach but it is also the way colleges teach software testing to the students”. In order to make sure the students do not fall into the old routine, the company has started several programs through its newly formed CleanSoft Academy. CleanSoft Academy is also actively seeking to increase its network amongst educational institutions to make software test engineering part of its academic program. CleanSoft Academy is working to close the increasing gap between Industry requirement and available pool of skills. Instead of generic programs, four streams of test professional programs that are aligned to market requirements are available as a choice to specialize.

HyBIST is a goal-centered methodology wherein the goal of software cleanliness is set up, potential defect types that can impede the cleanliness criteria identified, and then activities performed to ensure purposeful testing that is indeed effective and efficient. HyBIST has been applied by STAG in various domains like Mobile, Healthcare, ERP/SCM, Media, eLearning and more, over the last ten years in various process models including Agile. This has resulted in lowered defects escapes (up to 10x lower), increased test coverage (at least 3x), better RoI on automation, lower support costs (by 30 percent) with no increase in effort, time or costs.

You can also read the online version here or download a PDF copy of the article.

The tale of two doctors

In a big city lived Joe, a typical urban yuppie. He was always focused on a great tomorrow. He worked very hard, partied furiously and lived a fast life.

Life was a blast, until his body decided to act up. On this Sunday morning, he woke up panting, unable to breathe, body drenched in sweat, with a dull pain in his chest. The previous evening was a blast, a celebration party thrown for his best buddy getting engaged. After an evening spent at bowling, they hit the pubs, closing each one, until they could not find one open.

A typical Sunday morning would commence at noon; today, as he was rudely jolted out of his reverie, the bright LED clock showed 7:00.He could not move his arms, it seemed to take a tremendous effort to reach out for the bottle of Evian on the table near his bed. He had read about old age diseases getting younger in these modern times, dismissed them brashly, a reflection of his supreme yuppie confidence. For once he faltered, worried seriously if he could become one of the stories. All these years, he had thought of God of as a fashion statement but today he genuinely wished to believe that God exists. For the next few seconds, which seemed like an eternity, his mind rapidly flew back over the past years on the constant abuse he had heaped on his body. For once he prayed dearly that he would do the right things, if he was excused this time. The clock glowed 7:02, and he realized it had been the longest two minutes of his life.

At 8:55 a.m he was in the reception of GoodLife hospital for a 9AM appointment with Dr Robert Black Sr., a senior and very experienced cardiologist. He was soon ushered in, and was face to face with a severe yet friendly gentleman, a few orderly strands of golden hair on his shiny head with a piercing pair of eyes. “Mr Joe, would you please tell me your problem?” said Dr. Black. Joe described in detail his travails upon his rude awakening. An old school doctor, he believed in detailed physical examination rather than the fancy modern equipment. “Lie down on the bed and relax Mr Joe”. He took his stethoscope, placed it on his chest and listened carefully. “Breathe in and out deeply now” said the doctor as he continued to hover his steth on various parts of chest. His sharp eyes showed no emotion, as he went about his job confidently. The young nurse standing next to the doctor was petite and beautiful. She dispassionately took out the sphygmomanometer, wrapped the elastic band around Joe’s arm, pumped it up and watched the mercury bobbing up and down, while her other hand measured the pulse. After a minute, she looked at Dr Black and said 140/120 and 93, in a husky voice.

“Mr Joe, have you been feeling very tired at the end of day lately?”
“Yes” he said and added “It is the busy time of the year at work, a string of late nights.”
“What kind of work do you Mr Joe?”
“I work in the software industry. We are in midst of building a cool application for mobile phones”
“Oh I see, you are the software guy.My nephew is in the software business too and is always racing against time.”
“I guess you must be tied to the desk most of the time. Do you exercise?”
“Well doctor, the days are long and busy, I catch up on my sleep over the weekend. I try to workout in the gym over the weekends, but it is challenging”
“I see that you are smoker, do you drink? And are you a vegetarian?”
“Well doctor, I do drink, and I am not vegetarian.”

Dr Black was one of the most famous cardiologists in the country. He was a master at diagnosis, believed in scientific and systematic study of symptoms and their connections. He placed his gold-rimmed glasses on the table, rubbed his finger on his chin, leaned back on his cozy leather chair and his piercing eyes looked straight into Joe and said “Mr Joe, you have issue with the blood supply to the heart muscles, there seems a advanced arterial block. It is necessary that you undergo angioplasty, a procedure to relieve the constriction very quickly within a fortnight.”

Joe sat still, staring at the statement “The most amazing non-stop machine.Take care.” written on a poster containing the picture of heart, which prominently on the wall behind the doctor.

Dr Black who was used to these reactions, jolted Joe out of the reverie “Mr Joe, you need to quit smoking and go vegetarian. You are young, the angioplasty procedure has a high success rate and you should be back on to active life quickly.” Dr Black believed in conveying news straight, and expected patients to face reality and act on the problem. “Mr Joe, you would need to be in the hospital for 3-4 days, do decide on the date quickly. As I mentioned before, it is important that you act on this within a fortnight. It is painless procedure and should be fairly straightforward in your case. Mr Joe, do you have any questions?”

“No doctor, I have none” replied Joe mechanically, his ability to think numbed by the turn of events. As he exited the consulting room, the receptionist, a cheerful and bubbly woman in twenties whispered “Have a good day Mr Joe” with a beautiful smile, a genuine one. It had the effect, and for a moment he felt cheerful and returned the smile, a little weakly though.

As soon as he was outside the hospital, his hand went mechanically to his shirt pocket containing the cigarette packet. “Smoking kills” said the packet loudly and he threw the packet on the wayside.

David, his roommate had just woken up as Joe returned to his apartment. “Hi, had breakfast? Got some muffins and bagels, want some?” said David. “No thanks” mumbled Joe.

After a few minutes David understood the reason for the strange behavior of his best friend. “Come on man, let us get a second opinion right away”. David was one who never lost his cool and his level headed thinking in tough situations was one that helped his friends many a times.

At 10:50 they were at ValleyTech hospital for consultation with Dr James White. He had been referred by David’s boss, who had undergone a heart bypass a few months at ValleyTech.

At 11:05 Joe was called in. “Good morning Joe. Please sit down. I have read your case sheet and have a few questions. Do you have any recent ECGs?

“No doctor” said Joe.

“I know your company has a yearly health check plan for all, as our hospital administers it. So have you not taken it this year?”

“No doctor, the last few months has been very hectic and I have not had my yearly checkup yet” said Joe.

Dr White was a modern doctor who relied on technology in diagnosis and treatment. A young cardiologist,he believed in seeing the ‘internals’ before the
scalpel touched the body. He was amazed at the advancements in radiology and made it a point to recommend a few pictures to be taken before he touched a patient.

Unlike Dr Black who believed in the power of external examination, Dr White believed in the looking at internals for diagnosis and treatment. Dr White had immense faith in scans, lab tests and preferred analyzing reports to spending time on and performing examinations on patients.

“Please get the ECG done now. I would like to see the report first. Thank you.”

Joe went to the diagnostic lab in the adjoining building. When his turn came, he went inside, removed his shirt, the technician smeared jelly on his chest and proceeded to stick colorful leads at various points. In a few seconds, the needle was dancing, drawing patterns on the strip of paper. The technician looked at the squiggles on the paper with a bored expression, and after a few minutes, decided the machine has had its share of fun and switched it off. He tore the roll of paper, scanned it intently, and then proceeded to fold it and inserted into a cover. Joe was curious to know what the squiggles meant and asked “Is it normal?”.
“It seems fine, expect for a small spike here” replied the technician. He had seen hundreds of such squiggles and knew exactly as to what was normal, but he was no doctor to interpret any abnormalities.

Joe stared at the report, the squiggles held a secret that Joe was scared about. “Hey, let’s go meet to the doc” now said David breaking Joe’s train of negative thoughts.

“Show me the report Joe,” said Dr White.
Dr White held the strip of paper and rapidly scrolled it forward and then backwards.
“Were you treated for any heart related issue when you were young?” asked Dr White.
“No” said Joe, scared to ask questions.
“Joe, there is a slight aberration in the ECG, it may be nothing to be worry about. To confirm this, I recommend that you get the 128-slice beating heart scan. This the most advanced technology for diagnosis of heart related ailments that is available in the world and we are the only hospital in this city to have this. This gives a clear picture of the beating heart and enables clear diagnosis. And also take a chest X-ray too. I will be available until 1:00 PM, get it done right away and then see me”. He wrote down the lab request and handed it over to Joe.

“Hello, I need you to get ‘128-slice beating heart scan’ done. How much does it cost? Joe asked the grim looking gentlemen on the cash counter.
He was shocked at the cost of the hi tech scan, it seemed to have enough digits to max his credit card. Joe looked at David conveying in his look “They are milking us”.

Joe realized that the second opinion was going to be expensive and needed to think about this before he went on a diagnostic spree.

Joe was a professional software tester who diagnosed software for defects. He decided to chat with David over a cup of coffee to decide whether to go ahead with the expensive scan. David went to get the coffee while Joe sat down at the corner table, gazing at the birds fluttering over the little pond outside.

During this mindless gaze, staring at the chirpy birds, it suddenly flashed on him, the parallels between his profession and the doctor’s. In his job, he used black box techniques that required him to examine the system externally and find defects. He relied on deep understanding of the intended behavior, observation of behavior (“symptoms”) to design & refine his test cases. He had at times looked at internal information like architecture, technology, code structure to design test cases that were adept at catching issues related to structure.

His colleagues always used terms like “Black box testing” and “White box testing” and associated these to with system and unit levels respectively. Now he realized the general misconception that unit testing was white box testing and system box testing was black box testing. His train of thought was interrupted by hot coffee spilling on his shoulder followed by the shrill sound of glass breaking. “I am really sorry, hope you are ok” said the elderly woman who had tripped over the protruding leg of the gentleman at the neighboring table and spilt the hot cup of expresso that she was carrying. “I am fine, let me help you” said Joe as he helped pick up the glass shreds.

He realized that certain types of defects were better caught via “internal examination”(white box test techniques) while some are most suited to be caught via “external examination” (black box test techniques). He now understood that both of these test techniques were required at all levels to uncover effectively and efficiently.

Suddenly the diagnosis approach followed by Dr Robert Black and Dr James White became clear. As soon as David laid the steaming cup of Cafe Latte on the table, Joe had made the decision. He was not withdrawn or worried. The confidence was back and he would not let the ECG scroll spoil his fun.

The article was published in the April issue of “Tea-time with Testers” – an ezine on Software Testing.