Sanity testing
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A sanity test or sanity check is a basic test to quickly evaluate the validity of a claim or calculation. In mathematics, for example, when dividing by three or nine, verifying that the sum of the digits of the result is a multiple of 3 or 9 (casting out nines) respectively is a sanity test.
In computer science it is a very brief run-through of the functionality of a computer program, system, calculation, or other analysis, to assure that the system or methodology works as expected, often prior to a more exhaustive round of testing.
[edit] Mathematical
A sanity test can refer to various order of magnitude and other simple rule of thumb devices applied to cross-check mathematical calculations. For example:
- If one were to attempt to square 738 and calculated 53,874, a quick sanity check could show that this cannot be true. Consider that 500 < 738, yet 5002 = 521002 = 250000 > 53874. Since squaring preserves inequality for positive numbers (see inequality), this cannot be true and so the calculation was bad.
- In multiplication, 918 x 155 is not 142135 since 918 is divisible by three but 142135 is not (digits add up to 16 the digits of which do not add up to a multiple of three). Moreover, the product of an even and an odd number should be even, whereas 142135 is odd.
- When talking about quantities in physics, the power output of a car cannot be 700 kJ since that is a unit of energy, not power (energy per unit time). See dimensional analysis.
[edit] Software development
In software development, the sanity test (a form of software testing which offers "quick, broad, and shallow testing"[1]) determines whether it is reasonable to proceed with further testing.
Software sanity tests are commonly conflated with smoke tests [2]. A smoke test determines whether it is possible to continue testing, as opposed to whether it is reasonable[citation needed]. A software smoke test determines whether the program launches and whether its interfaces are accessible and responsible (for example, the responsiveness of a web page or an input button). If the smoke test fails, it is impossible to conduct a sanity test. In contrast, the ideal sanity test exercises the smallest subset of application functions needed to determine whether the application logic is generally functional and correct (for example, an interest rate calculation for a financial application). If the sanity test fails, it is not reasonable to attempt more rigorous testing. Both sanity tests and smoke tests are ways to avoid wasting time and effort by quickly determining whether an application is too flawed to merit any rigorous testing. Many companies run sanity tests on a weekly build as part of their development process [3]
The Hello world program program is often used as a sanity test for a development environment. If Hello World fails to compile the basic environment (or the compile process the user is attempting) has a configuration problem. If it works the problem may be a bug in the specific application being compiled.
