Software Testing Basics - Software Testing Interview Questions and Answers


  1. What is the difference between latent and masked defects?
    A latent defect is an existing defect that has not yet caused a failure because the sets of conditions were never met.

    A masked defect is an existing defect that hasn't yet caused a failure just because another defect has prevented that part of the code from being executed.
  2. Can you explain calibration?
    It includes tracing the accuracy of the devices used in the production, development and testing. Devices used must be maintained and calibrated to ensure that it is working in good order.
  3. What's the difference between alpha and beta testing?
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    Alpha and beta testing has different meanings to different people. Alpha testing is the acceptance testing done at the development site. Some organizations have a different visualization of alpha testing. They consider alpha testing as testing which is conducted on early, unstable versions of software. On the contrary beta testing is acceptance testing conducted at the customer end.

    In short, the difference between beta testing and alpha testing is the location where the tests are done.
  4. How does testing affect risk?
    A risk is a condition that can result in a loss. Risk can only be controlled in different scenarios but not eliminated completely. A defect normally converts to a risk.

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  5. What is coverage and what are the different types of coverage techniques?
    Coverage is a measurement used in software testing to describe the degree to which the source code is tested. There are three basic types of coverage techniques as shown in the following figure:

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    • Statement coverage: This coverage ensures that each line of source code has been executed and tested.
    • Decision coverage: This coverage ensures that every decision (true/false) in the source code has been executed and tested.
    • Path coverage: In this coverage we ensure that every possible route through a given part of code is executed and tested.
  6. A defect which could have been removed during the initial stage is removed in a later stage. How does this affect cost?
    If a defect is known at the initial stage then it should be removed during that stage/phase itself rather than at some later stage. It's a recorded fact that if a defect is delayed for later phases it proves more costly. The following figure shows how a defect is costly as the phases move forward. A defect if identified and removed during the requirement and design phase is the most cost effective, while a defect removed during maintenance is 20 times costlier than during the requirement and design phases.

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    For instance, if a defect is identified during requirement and design we only need to change the documentation, but if identified during the maintenance phase we not only need to fix the defect, but also change our test plans, do regression testing, and change all documentation. This is why a defect should be identified/removed in earlier phases and the testing department should be involved right from the requirement phase and not after the execution phase.