Software Development

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Software Development

• Software Testing

2
Testing Definitions

• There are many tests going under various names.
  The following is a general list to get a feel for
  the different types of testing required by during
  typical high quality software development.

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Acceptance Test

• The test performed by users of a new or changed
  system in order to approve the system and go live
• Usually carried out at the customers premises or
  using customers data with the customer being
  present
• This is usually the final phase of development
  and results in the handover of the software
  product to the customer

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Active / Passive Testing

• An active test introduces specific test data and
  the results of processing that data are observed
  for correctness
• Passive testing works on real data and the
  outputs are observed for correctness

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Alpha and Beta Testing

• Alpha testing is the first test phase carried out
  by the developers in the lab
• Beta testing is carried out when alpha testing is
  complete and the developers can find no errors
  (ideally). Beta testing is carried out by
  selected real users who report back to the
  developers. This enables the users to get early
  exposure to the software and the developers get
  usability and error feedback

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Automated Testing

• This is when software is used to test software.
  This enables test repeatability and is faster as
  the user is not generally required to enter lots
  of data manually
• If the code is changed in a single module, all
  the tests would be re-run on the whole
  application to ensure that the changes have not
  impacted on any other modules. Retesting
  everything in this way is often referred to as
  regression testing

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White and Black Box Testing

• White box testing requires knowledge of the
  internal operation of the software. This enables
  the test to chack all paths through a function
  for example
• Black box testing assumes no knowledge of the
  internal operation and based on the specification
  will input test data at a system level and
  observe the correctness of the output

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Dirty or Negative Testing

• This method requires data to be input such that
  it will maximise the chances of failure so is
  used to test the applications error recovery
  effectiveness
• Examples could be user input validation through
  to memory allocation failure

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Functional Testing

• Does the application do what it has been
  specified to do?
• Check all menu and tool bar options
• Check all keyboard input
• Likely to take the form of a task list which a
  tester goes through to check all options and
  navigation paths. This is not a usability test
  but initial feedback on usability could be
  collected at the same time

10
Recovery Testing

• How well does the application recover from
  hardware and software failure?
• Reading a data file which you know is always
  available will still need error recovery code in
  case the disk you are reading from fails
• How well does the system recover from the dirty
  test phase?
• What happens if the device your application is
  trying to communicate with does not respond?

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Test Case Testing

• This consists of a set of test data, test
  programs (test harnesses) and a set of expected
  results
• Typically a set of test cases is prepared (this
  is a test scenario). A file of input test data
  and expected results for example is read by the
  test harness (test driver program). A function
  (unit of code so is often referred to as a unit
  test) for example is called with the test data
  and the results are compared with the expected
  results. The success or failure of the test is
  reported and the next test is carried out. This
  method of testing tends to be totally automated
  if possible

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Test Suite

• This is a collection of test scenarios which
  themselves are a collection of test cases
• In oop for example, a test suite may consist of a
  test scenario for each class. The test scenario
  may consist of a series of tests for each of the
  member functions

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Usability Testing

• A series of tests carried out by users or subject
  experts to determine the ease of use
• Various techniques such as
• Task driven
• Observation
• Keystroke and mouse recording
• Interview
• Think aloud
• Questionnaires

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Test Driven Development

• This is not a test method as such but is test
  oriented. Based on the system requirements, a
  series of tests is specified which, when they
  pass, mean that a piece of working code has been
  produced. i.e. the test is specified before the
  software is written and the software is written
  to pass the test.
• Often used in Extreme Programming (XP) but can be
  used in its own right as a development method

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Compatibility Testing

• Ensures that the software is compatible with the
  hardware, operating systems, and other software
  packages that it will be working with such as
• Works on required software platforms such as
  Windows and Linux
• Works on required hardware platform such as 16,
  32 and 64 bit systems
• Works with various software releases if required
  such as Win 95, XP, Vista

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Performance Testing

• Ensures that the software runs fast enough to
  meet speed requirements e.g. executing
  algorithms in time specified
• Ensures that the software does not consume more
  memory than anticipated

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Function Stubs

• When developing an application as part of a team,
  you may need to call functions (or objects) that
  do not yet exist (because someone is still
  writing them
• Write a function which does nothing other than
  enable the caller to call it and return a value
  or series of values depending on the function
  spec.
• The caller can test the calling functions
  response to a variety of return values from the
  stubs

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Test Harness Example

• Performs 16 and 32 bit compatibility tests
• Performs Test Case Testing on a function
• Uses Automated Testing
• Uses Active Testing
• Data and results taken from a Test Scenario
• Function under test is a C function to convert a
  String to an Integer (like atoi but with extra
  features).
• Errors found would need source header updating
  with mod date and author and an overview of the
  problem and fix