Black-box testing uses external descriptions of the software, including specifications, requirements, and design to derive test cases. These tests can be functional or non-functional, though usually functional. The test designer selects valid and invalid inputs and determines the correct output. There is no knowledge of the test objects internal structure.
Validation Phases based on these steps
► Unit Testing
► Integration Testing
► System Testing
► User Acceptance Testing
The module design phase can also be referred to as low-level design. The designed system is broken up into smaller units or modules and each of them is explained so that the programmer can start coding directly. The low level design document or program specifications will contain a detailed functional logic of the module, in pseudocode:
► database tables, with all elements, including their type and size
► all interface details with complete API references
► all dependency issues
► error message listings
► complete input and outputs for a module.
The unit test design is developed in this stage.
The phase of the design of computer architecture and software architecture can also be referred to as high-level design. The baseline in selecting the architecture is that it should realize all which typically consists of the list of modules, brief functionality of each module, their interface relationships, dependencies, database tables, architecture diagrams, technology details etc. The integration testing design is carried out in the particular phase.
Systems design is the phase where system engineers analyze and understand the business of the proposed system by studying the user requirements document. They figure out possibilities and techniques by which the user requirements can be implemented. If any of the requirements are not feasible, the user is informed of the issue. A resolution is found and the user requirement document is edited accordingly.
In the Requirements analysis phase, the requirements of the proposed system are collected by analyzing the needs of the user(s). This phase is concerned about establishing what the ideal system has to perform. However it does not determine how the software will be designed or built. Usually, the users are interviewed and a document called the user requirements document is generated.
Many of the process models currently used can be more generally connected by the V-model where the “V” describes the graphical arrangement of the individual phases. The “V” is also a synonym for verification and validation.
The model is very simple and easy to understand. By the ordering of activities in time sequence and with abstraction levels the connection between development and test activities becomes clear. Oppositely laying activities complement one another i.e. serve as a base for test activities. So, for example, the system test is carried out on the basis of the results specification phase. The coarse view of the model gives the impressionthat the test activities first start after the implementation. However, in the description of the individual activities the preparatory work is usually listed. So, for example, the test plan and test strategy should be worked out immediately after the definition of the requirements. Nevertheless it can contribute very well to the structuring of the software development process.
The disadvantage of the model is the coarse division into constructive work (including the implementation) on the left-hand side of the “V” and the more destructive tasks on the right-hand side. Here also the impression may develop that, after the implementation phase, a ready product can be delivered. A planned-in removal of defects and regression test is not given.