(41 Describe the difference between white-box and black-box testing. (4.2) What circumstances necessitate black-box testing? (4.3) List and describe three general approaches to black-box testing. (4.4) What are equivalence classes, and what is their application to testing? (4.5) What are boundary values of equivalence classes? How do they guide test design? (4.6) How can equivalence classes and expected results coverage interact when designing tests? (4.7) What are some of the flaws arising from data conversions which testing can address? From dates and their representations? (4.8) List and define five forms of test coverage. What levels of each notion of coverage are possible in a nontrivially-sized software project? What is feasible? 4.9) What usages in source code should attract particular attention under white-box testing