Statement coverage is also known as line coverage. The formula to calculate statement coverage is:
Statement Coverage=(Number of statements exercised/Total number of statements)*100
Studies in the software industry have shown that black-box testing may actually achieve only 60% to 75% statement coverage, this leaves around 25% to 40% of the statements untested.
To illustrate the principles of code coverage lets take one pseudo-code which is not specific to any programming language. We have numbered the code lines just to illustrate the statement coverage example however this may not always be correct.
PRINT “X is greater than Y”
Let us see how can we achieve 100% code coverage for this pseudo-code, we can have 100% coverage by just one test set in which variable X is always greater than variable Y.
TEST SET 1: X=10, Y=5
A statement may be a single line or it may be spread over several lines. A statement can also contain more than one statement. Some code coverage tools group statements that are always executed together in a block and consider them as one statement.