There are two kinds of testing strategies. The first type of strategy relates to how logic is tested in the application. Logic testing strategies are either black-box or white-box. Black-box testing strategies assume that module (or program or system) testing is concerned only that what goes in comes out correctly. The details of logic are hidden and not specifically analyzed. Black-box strategies are data-driven, which means that all test cases are based on analysis of data requirements for the test item.
White-box approaches to testing assume that specific logic is important and to be tested. White-box tests evaluate some or all of the logic of a test item to verify correct functioning. White-box strategies are logic-driven,
which means that all test cases are based on analysis of expected functions of the test item.
FIGURE 17-6 Testing Information Flow
The second type of testing strategy relates to how testing is conducted, regardless of logic testing strategy. These conduct, or process, strategies are top-down and bottom-up. Both top-down and bottom-up testing fit the project life-cycle phases in Figure 17 -1; the difference is in the general approach.
Top-down is incremental; bottom-up is 'all or nothing'. Top-down testing assumes the main application logic is most important. Therefore, the main logic should be developed and tested first and continuously throughout development. Continuous successful testing raises confidence levels about code reliability. Program stubs that contain minimal functional logic are tested first with additional logic added as it is unit tested. Top-down testing frequently requires extra code, known as scaffolding,
to support the stubs, partial modules, and other pieces of the application.
Bottom-up testing assumes that individual programs and modules are fully developed as standalone processes. These are tested individually, then combined for integration testing. Bottom-up testing treats test phases as somewhat discrete. Unit testing leads to integration testing which leads to system testing. The next section discusses variations of black-and white-box testing strategies.
Source: Sue Conger, https://learn.saylor.org/pluginfile.php/236045/mod_resource/content/2/The%20New%20Software%20Engineering.pdf
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