White box testing (a.k.a. clear box testing, glass box testing or structural testing) uses an internal perspective of the system to design test cases based on internal structure. It requires programming skills to identify all paths through the software. The tester chooses test case inputs to exercise paths through the code and determines the appropriate outputs. In electrical hardware, testing every node in a circuit may be probed and measured; an example is #-Link-Snipped-# (ICT).
Since the tests are based on the actual implementation, if the implementation changes, the tests probably will need to also. For example ICT needs updates if component values change, and needs modified/new fixture if the circuit changes. This adds financial resistance to the change process, thus buggy products may stay buggy. <a href="https://en.wikipedia.org/wiki/Automated_optical_inspection" target="_blank" rel="nofollow noopener noreferrer">Automated optical inspection - Wikipedia</a> (AOI) offers similar component level correctness checking without the cost of ICT fixtures, however changes still require test updates.
#-Link-Snipped-#
While white box testing is applicable at the <a href="https://en.wikipedia.org/wiki/Unit_testing" target="_blank" rel="nofollow noopener noreferrer">Unit testing - Wikipedia</a>, <a href="https://en.wikipedia.org/wiki/Integration_testing" target="_blank" rel="nofollow noopener noreferrer">Integration testing - Wikipedia</a> and <a href="https://en.wikipedia.org/wiki/System_testing" target="_blank" rel="nofollow noopener noreferrer">System testing - Wikipedia</a> levels of the <a href="https://en.wikipedia.org/wiki/Software_testing" target="_blank" rel="nofollow noopener noreferrer">Software testing - Wikipedia</a> process, it is typically applied to the unit. While it normally tests paths within a unit, it can also test paths between units during integration, and between subsystems during a system level test. Though this method of test design can uncover an overwhelming number of test cases, it might not detect unimplemented parts of the specification or missing requirements, but one can be sure that all paths through the test object are executed.
Typical white box test design techniques include:<a href="https://en.wikipedia.org/wiki/Control_flow" target="_blank" rel="nofollow noopener noreferrer">Control flow - Wikipedia</a>testing
Data flow testing
source:wikipedia
do check this out too..
#-Link-Snipped-#
