Sanity testing your code

This is a very simple way of testing your code or hypothesis, but lot of people don’t do it and end up wasting lot of time on exhaustive round of bug testing.
According to Wikipedia:

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 multiplying 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.

In software development, the sanity test determines whether it is reasonable to proceed with further testing. Software sanity tests are commonly conflated with smoke tests. A smoke test determines whether it is possible to continue testing, as opposed to whether it is reasonable. 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.