To measure the proportion of a program exercised by
using a test suite, generally represented by a percentage. It
is typically involve a collecting information about the parts
of a program, which are actually executed when running the
test cases in order to, identify which particular branches of
conditional statements have been taken. The basic level of
test coverage is code coverage testing and the most
methodical level of test coverage is path coverage testing.
There are some intermediate levels of test coverage exist,
but they are rarely used.