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Development models

Chapter 3 introduces different types of software development lifecycle models (also referred to more simply as “development models”). These are designed to aid structuring, planning, and management of new or continuing software projects. In order to perform well-structured tests, you will usually need more than just a description of the activities that make up the development model. In addition to positioning testing within the overall development process, you will also need a detailed dedicated testing schedule. In other words, the content of the development task called “testing” needs to be broken down into smaller, more manageable steps.

Testing comprises a sequence of individual activities

There are many widely used and proven test activities, and a test process will be made up of these kinds of activities. You need to put together a suitable test process according to the specified (or inherited) project situation. The specific test activities you choose, and how (and when) you implement them will depend on a number of factors, and will generally be based on a company or project-specific testing strategy (see section 6.2). If you ignore certain test activities you will increase the likelihood of the test process failing to reach its objectives.

Fig. 2-3 The testing process

The main activities

A test process⁸ will generally comprise the following activities (see figure 2-3):

 Test planning

 Test monitoring and control

 Test analysis

 Test design

 Test implementation

 Test execution

 Test completion

Each of these activities comprises multiple individual tasks that produce their own output and vary in nature according to the project at hand.

Fig. 2-4 The test process showing time overlap

Iterative testing

Even if the individual tasks involved in the test process are defined in a logical sequence, in practice they can (and may) overlap, and are sometimes performed concurrently (see figure 2-4). Even if you intend to perform your test activities in a predefined sequence, a sequential development model (for example, the “waterfall” model) can cause overlap, combination, concurrency, or cancellation of individual activities or parts of activities.

Adapting these activities to fit the system and project context (see below) is usually necessary, regardless of which development model you are using.

Fig. 2-5 An iterative test process

Software is often developed in small iterative steps—for example, agile development methods use continuous build and test iterations. The corresponding test activities therefore need to take place continuously and iteratively (see figure 2-5).

The following sections provide an overview of the individual test steps and their output. Test management is responsible for the monitoring and execution of most of these activities, which are described in detail in Chapter 6 (see sections 6.2 and 6.3).