Taking visibility for granted?

Testers are naturally curious people. We enjoy the creation of questions for the purpose of finding the truth, or better still for the purpose of creating new truths. For centuries, the true professional testers have been scientists who more often than not were the determiners of new truths and thus we recall them as inventors. Back in the mid-1700's a theologian and scientist Joseph Priestley conducted several experiments to determine what types of gasses were generated by plants. It started with a curiosity about the observed behavior of a wax candle burning within a glass jar. And it was truly a curious thing because the wax candle burned out long before it exhausted the fuel supply of wax or wick. The flame had consumed all of the fuel supply of oxygen from the sealed environment, proven by the fact that when he tried to re-ignite the candle inside the jar using a simple magnifying glass to converge intense rays of sunlight on the candle's wick, it failed.


When Priestley attempted the same experiment but this time adding a sprig of mint into the glass jar with the candle the result was similar at first: the candle burns, oxygen is consumed, candle goes out, can't re-ignite it with sunbeams. But after nearly a month with the candle left isolated in the jar with the sprig of mint, Priestley then re-attempted to ignite the candle with the magnifying glass and rays of sunshine. And of course it worked. The candle was lit and once again consumed the oxygen until it burned out. Priestley deduced that the plant was somehow producing a gas that allowed the candle's flame to burn once again. What he could not have predicted, is that he would be the first to discover a new truth about the role of oxygen in photosynthesis.


Priestley's methods really got me thinking, especially about his test tools and techniques. All he used were rudimentary equipment and simple deductive reasoning for analysis. What if we were to attempt this same experiment today using contemporary scientific inventions? We would probably use a oxygen sensor to measure the amount of oxygen in the jar. This would make all the other implements for the experiment obsolete: the wax candle, the magnifying glass, the need for bright sunshine. The creation of the lambda probe oxygen sensor in the late 1960's was a response to the demand for measurement of oxygen in an experiment, machine or system. The design of the sensor allowed for visible measurement of an invisible gas. Even Priestly himself would have appreciated the sensor not simply for the new visibility it provided, but for the ease of use and accuracy in measuring his experiment.


For Priestley in the mid-1700's photosynthesis was unknown and oxygen was both invisible and immeasurable. Boris Beizer more than 200 years later was challenged to measure the known workings of the computer which were, for all intents and purposes, inside an invisible black box. The discoveries and solutions that resulted from their work show us how inappropriate it is to take any prior science for granted and also provide for us a new baseline for how to test. Simply, it is easier to correlate a visible test measurement to the tests objectives or pass/fail criteria. As a result, testing tools today already make test measurements visible, actionable and automatically correlate* the results back to pass/fail criteria. Today we take for granted that nearly every testing tool comes with mechanisms for "making visible" the performance metrics from the system under test. Just as we take for granted that every modern automobile now uses oxygen sensors and an onboard computer as essential components to improve fuel efficiency.


But just making something visible isn't enough. Consider LoadRunner's monitoring and diagnostics capabilities. Could you imagine today having to monitor CPU resource utilization without having the test tool automatically make the measurement visible for you? In the 1980's Boris Beizer shared stories about his counting CPU ticks with an AM radio next to the machine. That sounds like such an old solution - almost like having to measure oxygen with a wax candle in a jar. My point is that visibility should be understood as a means to improving measurability. Measurability is what truly accelerates the testing process. Innovation in performance testing should improve and extend the visibility and measurability we have today. What more can we make visible? What new methods of measuring, arranging and correlating test data can we create? Can we automate the capabilities we have today or build intelligence to aggregate or parse this new data?


And we don't have to start with a wax candle in a jar or an AM radio.


*- see lr_end_transaction("login", LR_FAIL);

Comments
(anon) | ‎03-22-2009 06:24 AM

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About the Author
Mark Tomlinson is a software tester and test engineer. His career began in 1992 with a comprehensive two-year test for a life-critical trans...


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