Insights of software testing design from the view of Venn diagram.

$($a$)$ In software testing, the program behaviors can be categorized into specification$-$based and code$-$based.

Please explain the differences between this two views, and how these two views influence the test design.

$($b$)$ Use the Venn diagram to describe the relation between the specification$-$based view and code$-$based view

of the program behavior.

$($c$)$ Use the Venn diagram to describe the relation between the test cases and two views of program behaviors.

$($d$)$ Analyse all the set intersections $($regions$)$ identified in $($c$).$

$($e$)$ Identify the region the tester should works on and explain why