Software Testing Models

Scrum Development Process

Scrum is an agile method for project management. Scrum is a method for managing work and achieving very high productivity. A popular agile method for project management, Scrum is noted for its simplicity, its high level of transparency, and a team based approach to work.
Characteristics of Scrum
a. A product backlog of prioritized work to be done;
b. Completion of a fixed set of backlog items in a series of short iterations or sprints;
c. A brief daily meeting or scrum, at which progress is explained, upcoming work is described and impediments are raised.
d. A brief sprint planning session in which the backlog items for the sprint will be defined.
e. A brief sprint retrospective, at which all team members reflect about the past sprint.
Following are some practices for the Scrum:
a. Customers become a part of the development team. (i.e., Customer must be genuinely interested in the output.)
b. Frequent intermediate deliveries with working functionality.
c. Frequent risk and mitigation plans developed by the development team itself. Make it live, and continuous activity.
d. Daily status discussion with the team. – Standup meetings.
e. A daily discussion asking each team member:
1. What have you done since yesterday?
2. What are you planning to do by tomorrow?
3. Do you have any problems preventing you from accomplishing your goal?
f. Transparency in planning and module development – Let everyone know, who is accountable for what and by when.
g. Workplaces and working hours must be energized. – "Working more hours" does not necessarily mean "producing more output."
Waterfall Model
This is the most common and classic of life cycle models, also referred to as a linear-sequential life cycle model. It is very simple to understand and use. In a waterfall model, each phase must be completed in its entirety before the next phase can begin. At the end of each phase, a review takes place to determine if the project is on the right path and whether or not to continue or discard the project.
a. Simple and easy to use.
b. Easy to manage due to the rigidity of the model – each phase has specific deliverables and a review process.
c. Phases are processed and completed one at a time.
d. Works well for smaller projects where requirements are very well understood.
a. Adjusting scope during the life cycle can kill a project
b. Poor model for complex and object-oriented projects.
c. Poor model for long and ongoing projects.
d. Poor model where requirements are at a moderate to high risk of changing.
V-Shaped Model
Just like the waterfall model, the V-Shaped life cycle is a sequential path of execution of processes. Each phase must be completed before the next phase begins. Testing is emphasized in this model more so than the waterfall model though. The testing procedures are developed early in the life cycle before any coding is done, during each of the phases preceding implementation.
Requirements begin the life cycle model just like the waterfall model. Before development is started, a system test plan is created. The test plan focuses on meeting the functionality specified in the requirements gathering.
The high-level design phase focuses on system architecture and design. An integration test plan is created in this phase as well in order to test the pieces of the software systems ability to work together.
The low-level design phase is where the actual software components are designed, and unit tests are created in this phase as well.
The implementation phase is, again, where all coding takes place. Once coding is complete, the path of execution continues up the right side of the V where the test plans developed earlier are now put to use.
a. Simple and easy to use.
b. Each phase has specific deliverables.
c. Higher chance of success over the waterfall model due to the development of test plans early on during the life cycle.
d. Works well for small projects where requirements are easily understood.
a. Very rigid, like the waterfall model.
b. Software is developed during the implementation phase, so no early prototypes of the software are produced.
c. Model doesn’t provide a clear path for problems found during testing phases.
Spiral Model
The spiral model gives more emphases placed on risk analysis. The spiral model has four phases: Planning, Risk Analysis, Engineering and Evaluation. A software project repeatedly passes through these phases in iterations (called Spirals in this model). The baseline spiral, starting in the planning phase, requirements are gathered and risk is assessed. Each subsequent spirals builds on the baseline spiral.
Requirements are gathered during the planning phase. In the risk analysis phase, a process is undertaken to identify risk and alternate solutions. A prototype is produced at the end of the risk analysis phase.
Software is produced in the engineering phase, along with testing at the end of the phase. The evaluation phase allows the customer to evaluate the output of the project to date before the project continues to the next spiral.
In the spiral model, the angular component represents progress, and the radius of the spiral represents cost.
a. High amount of risk analysis.
b. Good for large and mission-critical projects.
c. Software is produced early in the software life cycle.
a. Can be a costly model to use.
b. Risk analysis requires highly specific expertise.
c. Project’s success is highly dependent on the risk analysis phase.
d. Doesn’t work well for smaller projects.

Related Testing Topic
a. Black Box testing

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