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    • Introduction to Software Testing

      Goal of testing

      §The goal of a software tester is:
      •To find bugs
      •To find them as early as possible
      •make sure they get fixed

      §Testing is a means to:
      •Find bugs
      •Provide confidence and information
      •Even prevent defects

      Why is testing needed
      § A defect in the software has a root cause, while the effect of defect is
      seen as impact by the different stake holders.

      §Testing is part of overall Quality Assurance – It covers the Quality
      Control aspect of ensuring Quality

      §A fault doesn't necessarily result in a failure, but a failure can only occur if a
      fault exists. To avoid a failure you must find the fault.

      §Software testing may be required for compliance with contractual or legal requirements

      §When is testing complete?
      • Actually never
      • However for practical reasons it is stopped after considering the risks involved, time and budget constraints

      Testing should provide sufficient information to the stake holders for decision making
      regarding release of the software/ system , for the next development step or handover
      to customers.
      Why is testing needed
      §Complexity of software makes it error prone
      §Untested or weakly tested software can cause losses in real life. Eg:

      •Disney’s Lion King – 1994 – 1995- The software did not work on
      the most common systems that the public had.
      •Intel Pentium Floating-Point Division Bug – 1994 – Intel took a
      charge of more than $400 million to cover the costs of replacing
      bad chips
      •NASA Mars Polar Lander – 1999 – Malfunction due to an
      unexpected setting of a single data bit
      •Patriot missile defense system – 1991 – A software bug caused
      the tracking system to be inaccurate after 14 hrs of operation

      qSoftware bugs can cause harm to a person, to the environment or to a

      Who makes a Good tester

      The tester’s mindset must have the below mentioned attributes

      §Keen Observation
      §Questioning Skills
      §“Never give-up” attitude
      §Interpersonal Skills

      “Behind every great Developer there is an equally great Tester..””

      The V-Model
      The V-model can be said to have developed as a result of the evolution of software testing. Various testing
      techniques were defined and various kinds of testing were clearly separated from each other which led to the waterfall model evolving into the V-model. The tests in the ascending (Validation) hand are derived
      directly from their design or requirements counterparts in the descending (Verification) hand. The ‘V’ can also stand for the terms Verification and Validation.

      The V-model deploys a well-structured method in which each phase can be implemented by the detailed documentation of the previous phase. Testing activities like test designing start at the beginning of the project well before coding and therefore saves a huge amount of the project time.

      Verification Phases
      •Requirements analysis
      •System Design
      •Architecture Design
      •Module Design
      Validation phases
      •Unit Testing
      •Integration Testing
      •System Testing
      •User Acceptance Testing

      SDLC and STLC

      The Testing Process

      http://istqb.org/download/attachments/2326555/Foundation Level Syllabus (2010).pdf

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