Smoke testing refers to various classes of tests of systems, usually intended to determine whether they are ready for more robust testing. The expression probably was first used in

plumbing Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses piping, pipes, valves, piping and plumbing fitting, plumbing fixtures, Storage tank, tanks, and other apparatuses to convey fluids. HVAC, Heating and co ...

in referring to tests for the detection of cracks, leaks or breaks in closed systems of pipes.Stevenson, Thomas.
A Treatise on Hygiene and Public Health, Volume 1
'. J. & A. Churchill. 1892, p. 776. By metaphorical extension the term is used in

electronics Electronics is a scientific and engineering discipline that studies and applies the principles of physics to design, create, and operate devices that manipulate electrons and other Electric charge, electrically charged particles. It is a subfield ...

. In ''Lessons Learned in Software Testing'', Cem Kaner, James Bach, and Brett Pettichord provided the origin of the term: "The phrase ''smoke test'' comes from

electronic Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductors * ''Electronics'' (magazine), a defunct American trade journal *Electronic storage, the storage of data using an electronic device *Electronic c ...

hardware testing. You plug in a new board and turn on the power. If you see smoke coming from the board, turn off the power. You don't have to do any more testing."Kaner, Bach, and Pettichord. ''Lessons Learned in Software Testing''. Wiley Computer Publishing, 2002, p. 95.

In electronics and electrical engineering

and

electrical engineering Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity, electronics, and electromagnetism. It emerged as an identifiable occupation in the l ...

, the term smoke test or power on test is used to refer to the first time a circuit under development is attached to power, which will sometimes produce actual smoke if a design or wiring mistake has been made. Most often, this smoke comes from burning

resistor A resistor is a passive two-terminal electronic component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...

s, which produce a distinctive smell due to the

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

resin coating combusting. For certain circuits, overheating and burning due to circuitry that is still not properly operating can be avoided by slowly turning up the input voltage to the unit under test by using a variable

autotransformer In electrical engineering, an autotransformer is an electrical transformer with only one winding. The " auto" (Greek for "self") prefix refers to the single coil acting alone. In an autotransformer, portions of the same winding act as both the p ...

and watching the

electric current An electric current is a flow of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is defined as the net rate of flow of electric charge through a surface. The moving particles are called charge c ...

consumption. Overloaded integrated circuits typically produce "blue smoke" (or magic smoke). "Blue smoke" is the subject of jokes among technicians who refer to it as if it were a

genie GEnie (General Electric Network for Information Exchange) was an online service provider, online service created by a General Electric business, GEIS (now GXS Inc., GXS), that ran from 1985 through the end of 1999. In 1994, GEnie claimed around ...

in the circuit: ''It's the blue smoke that makes it work—let out the blue smoke and it won't do anything.''

References

{{DEFAULTSORT:Smoke testing Tests Smoke