Software Bugs, Errors, And Defects

Bugs, errors, and defects may all be found on software. These are what we call “failures” and affect the functionality of software.

Software Bugs

If testers find any mismatch in the application/system in testing phase then they call it as Bug.

A software bug is a problem causing a program to crash or produce invalid output. A bug can be an error, mistake, defect or fault, which may cause failure or deviation from expected results. Most bugs are due to human errors in source code or its design.

Software Bugs Explained

Some bugs might not have serious effects on the functionality of the program and may remain undetected for a long time. Another category of bugs called security bugs may allow a malicious user bypass access controls and obtain unauthorized privileges.

Worst Bugs in Software History

  • Bugs in the code controlling the machine called Therac-25, used for radiation therapy, lead to patient deaths in the 1980’s
  • In 1996, the $1.0 billion rocket called Ariane 5 was destroyed a few seconds after launch due to a bug in the on-board guidance computer program.
  • A bug in the flight software for the Mariner I spacecraft caused the rocket to change path from the expected path. This hapened in 1962.
  • In the 1990s, a bug was found in the new release of AT&T’s software control #4ESS long distance switches caused many computers to crash.

Software Errors

Software error refers to error resulting from bad code in some program involved, hence in producing the erroneous result. An error is a deviation from accuracy or correctness.

Categories of Software Errors

  • Functionality Errors: Functionality is a way the software is intended to behave. Software has a functionality error if something that you expect it to do is hard, awkward, confusing, or impossible.
  • Communication Errors: These errors occur in communication from software to end-user. Anything that the end user needs to know in order to use the software should be made available on screen.
  • Missing command errors: This happens to occur when an expected command is missing.
  • Syntactic Error: Syntactic errors are misspelled words or grammatically incorrect sentences and are very evident while testing software GUI. Please note that we are NOT referring to syntax errors in code. The compiler will warn the developer about any syntax errors that occur in the code.
  • Error handling errors: Any errors that occur while the user is interacting with the software needs to be handled in a clear and meaningful manner.
  • Calculation Errors: These errors occur due to any of the following reasons. They are Bad logic, Incorrect formula, Data type mismatch, Coding errors, Function call issues , and many more.
  • Control flow errors: The control flow of a software describes what it will do next and on what condition.

Software Defects

A Software defect is a condition in a software product which does not meet a software requirement (as stated in the requirement specifications) or end-user expectation (which may not be specified but is reasonable).

Team members usually think of ‘defect’ as meaning something is wrong. But, how do testers really identify what is wrong when testing a program? Are defects always incorrect behavior or can they be something unusual or something that is not great? Recognizing defects is not always as straightforward as it seems, but studying how testers identify defects can help define what they are. 

Software Bugs, Errors, And Defects

To Wrap Up

How many of you have wondered about the difference in bugs and defects? How many would argue they both are the same? And how do you define if an issue is within or out of the scope of a sprint?

A defect is any variance between actual and likewise expected result . A mistake in code is called Error. Error found by tester is called defect. Defect accepted by development team is called Bug. And build does not meet the requirements then it is Failure.

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