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Smoke testing refers to the first test made after assembly or repairs to a system, to provide some assurance that the system under test will not catastrophically fail. After a smoke test proves that “the pipes will not leak, the keys seal properly, the circuit will not burn, or the software will not crash outright,” the system is ready for more stressful testing.
The term smoke testing is used in several fields, including electronics, computer software development, plumbing, woodwind repair, infectious disease control, and the entertainment industry.
History of the term
“The phrase smoke test comes from 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.”
Smoke testing in Software development
In computer programming and software testing, smoke testing is a preliminary to further testing, intended to reveal simple failures severe enough to reject a prospective software release. In this case the smoke is metaphorical. A subset of test cases that cover the most important functionality of a component or system are selected and run, to ascertain if the most crucial functions of a program work correctly. For example, a smoke test may ask basic questions like “Does the program run?”, “Does it open a window?”, or “Does clicking the main button do anything?” The purpose is to determine whether the application is so badly broken that further testing is unnecessary. Smoke tests broadly cover product features in a limited time … if key features don’t work or if key bugs haven’t yet been fixed, your team won’t waste further time installing or testing.
Smoke testing performed on a particular build is also known as a build verification test.
A daily build and smoke test is among industry best practices. Smoke testing is also done by testers before accepting a build for further testing. Microsoft claims that after code reviews, “smoke testing is the most cost effective method for identifying and fixing defects in software”. In Microsoft’s case a smoke test is the process of validating code changes before they are checked into source control.
Smoke tests can either be performed manually or using an automated tool. When automated tools are used, the tests are often initiated by the same process that generates the build itself.
Smoke tests can be broadly categorized as functional tests or unit tests. Functional tests exercise the complete program with various inputs. Unit tests exercise individual functions, subroutines, or object methods. Both functional testing tools and unit testing tools tend to be third-party products that are not part of the compiler suite. Functional tests may be a scripted series of program inputs, possibly even with an automated mechanism for controlling mouse movements. Unit tests may be separate functions within the code itself, or driver layer that links to the code without altering the code being tested.
