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Design, Development and Testing

Why testing runs throughout development

  • 3 things to know
  • AS Unit 1

Overview

System quality, four qualities by which a finished system is judged and quality assurance.

What you need to know

Answer each one before you reveal it.

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Key term

Why is regression testing necessary after a fault has been corrected?

Key term

Why is testing carried out throughout development rather than only at the end?

Process

Explain how the cost of correcting a fault changes with the stage at which it is found.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Why is testing carried out throughout development rather than only at the end?

    Model answer

    A fault found soon after it is made affects only the work done since, while the same fault found at the end may be built into many modules and into the documentation as well.

  2. 2

    Explain how the cost of correcting a fault changes with the stage at which it is found.

    Model answer

    The cost rises sharply at each stage, because a fault found in a requirement means changing a document, while the same fault found after handover means changing the design, the code, the tests and the live data.

  3. 3

    What is meant by system quality?

    Model answer

    System quality is the degree to which a system does what its users need, does it reliably and correctly, and can be used and maintained without difficulty.

  4. 4

    Name four qualities by which a finished system is judged.

    Model answer

    A finished system is judged on its correctness, its reliability, its usability and its maintainability.

  5. 5

    What is quality assurance?

    Model answer

    Quality assurance is the set of planned activities, such as standards, reviews and testing, put in place to make sure the system being built will reach the required standard.

  6. 6

    What is regression testing?

    Model answer

    Regression testing re-runs earlier tests after a change has been made, to confirm that the change has not broken anything that previously worked.

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