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.
READ X
READ Y
IF X>Y
PRINT “X is greater than Y”
ENDIF
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.
