Applying Fail Fast in Software Development

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Applying Fail Fast in Software Development
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Intro

• For any regular programmer, the motivation while
  writing code is to reduce defects and avoid
  system from crashing. Such a motivation results
  in implementing defensive coding. Every software
  engineer has to agree with debugging concept.
  Debugging is most difficult part of software
  development cycle (SDLC). It is also observed
  that the defects which are easy to produce are of
  the least concern to the developer. In fact, the
  criticality of the defect is directly
  proportional to the frequency of its occurrence,
  rather than the actual flow that the defect
  breaks. My observation teaches me the most of the
  time these rarely producible defects are due to
  defensive coding.

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Heres an example
Above code snippet is good example for defensive
coding.
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• FirstOrDefault returns a first item of
  potentially multiple (or default if none
  exists).
• SingleOrDefault assumes that there is a single
  item and returns it (or default if none exists).
  Multiple items are a violation of contract, an
  exception is thrown.
• Here there is no possibility of getting more than
  one user with provided username and if it
  consists multiple users with same names, then
  system will eventually fail (Not instantly).
  Developers are aware of results, as outcome would
  be single user or null. But, developer prefers to
  forgive the system rather than failed results
  from the system. Tough there is a high chance of
  injecting one of that rarely producing defects.
• And also, you might be wondering to prepare our
  system fragile. I would say NO, because this
  mantra makes our system more robust and amenable.
  Spartan always says the more you sweat in
  training, the less you bleed in combat, and the
  same applies here the more defects found in
  testing, the lesser are produced during
  production.

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Heres another example
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• You can notice the difference of Fail Fast
  approach which is mentioned in the above code
  snippet, that developers wont assume that the
  conversation would correctly execute.
  Nonetheless, the system works more fragile and
  hence to be sure of successful execution and
  conversation the latter approach is undertaken.
• This approach hasnt come up overnight. The
  learning in the aforementioned two examples has
  come after letting the system fail for the first
  time, so as to conclude on a better and more
  stable approach later. Hence, I would prefer to
  fail fast and fail visibly.

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Benefits of Fail Fast approach

• Benefits of Fail Fast approach is, you will fail
  instantly and find the exact problem in your
  system. There will be exceptions for some really
  nagging defects, but for some incidents such as
  the following the fail fast approach will be most
  helpful
• Getting/Setting Configuration parameters
• Fetching data from database (most of time I see
  data access layer is always in try/catch so if
  connection goes down it always returns null, and
  I dont know what actually happened avoid this)
• Your business rules are clear (for e.g. one
  username will be mapped to single unique user,
  never multiple)

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• Original Source
• http//www.azilen.com/blog/applying-fail-fast-soft
  ware-development/

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