The Art of Software Testing

Chapter 9: Testing In The Agile Environment


Glen Myers
Wiley
Third Edition, 2012





  • The twenty-first century customer demands a quality application delivered almost immediately

  • In 2001 a group of developers met to discuss the state of lightweight (not too many rigorous rules) and rapid development methodologies

  • They created the "Manifesto for Agile Software Development," a document that became the cornerstone of the Agile movement

    We are uncovering better ways of developing software by doing it and helping others do it

    Through this work we have come to value:
    Individuals and interactions over processes and tools
    Working software over comprehensive documentation
    Customer collaboration over contract negotiation
    Responding to change over following a plan

    That is, while there is value in the items on the right, we value the items on the left more

  • Agile is a philosophy that focuses on customers and employees, in lieu of rigid approaches and hierarchies

    Features of Agile Development

  • Agile development promotes iterative and incremental development, with significant testing, that is customer-centric and welcomes change during the process

  • Knowing their interaction is welcomed helps customers build satisfaction and confidence in the end product and in the development team

  • Many rapid development approaches may be considered Agile

  • They rely on customer involvement, mandate significant testing, and have short, iterative development cycles

  • The two most popular are Scrum and eXtreme Programming (XP)

  • Almost identical except...

    1. Scrum teams typically work in iterations (called Sprints) that are from two weeks to one month long
    XP teams typically work in iterations that are one or two weeks long

    2. Scrum teams do not allow changes during their Sprints
    Once the Sprint Planning Meeting is completed and a commitment made to delivering a set of product backlog items, that set of items remains unchanged through the end of the Sprint
    XP teams are much more amenable to change within their iterations

    3. eXtreme Programming (XP) teams work in a strict priority order
    Features to be developed are prioritized by the customer (Scrum's Product Owner)
    The team is required to work on them in that order
    Scrum Product owner prioritizes the product backlog but the team determines the sequence in which they will develop the backlog items

    Agile Testing

  • Collaborative testing
    Everyone is involved in the process through design, implementation, and execution of the test plan
    This requires a lot of communication and collaboration

  • As with most aspects of Agile development, Agile testing necessitates engaging the customer as early as possible and throughout the development cycle

  • Developers run unit tests for every incremental code change, no matter how small, to ensure that the code base still meets its requirements

    Agile Programming Basics

  • Avoids the large-scale project syndrome in which the customer and the programming team meet to design every detail of the application before coding begins

  • Customer requirements constantly change to reflect new business situations or marketplace conditions

  • Traditional software development models suggest you code first and create testing interfaces later
    In Agile, you must create the unit tests first, and then write the code to pass the tests

    Agile Planning

  • Planning in Agile focuses on identifying your customer's application requirements and designing use cases (and user stories derived from them)

  • Customer employs the user stories when performing acceptance tests at the end of a release cycle

    Pair programming

  • Two programmers work together, at the same machine, to create the code

  • This allows for real-time code review, which dramatically facilitates bug detection and resolution

    Agile Testing

  • Constant testing leads to the intangible benefit that the programmers and customers have confidence that the code is of high quality

  • Agile mandates creating tests before coding begins, not after

  • If you create the unit tests before coding, you must understand the requirements

  • It forces you to understand the requirements and to resolve ambiguities before you begin coding

    Agile Acceptance Testing

  • You and the customer create the acceptance tests during the design/planning phases

  • Create the acceptance tests from user stories

  • Customers, not programmers, conduct the acceptance tests
    In this manner, customers provide the unbiased verification that the application meets their needs

  • After you correct the bugs, or after any change, the customer reruns the acceptance tests
    In this manner, the acceptance tests also become a form of regression testing