Final answer:
Test coverage indicates how much of the source code is tested by a test suite, with several criteria like statement coverage, function coverage, and branch coverage determining different levels of granularity.
Step-by-step explanation:
Test coverage is a metric used in software testing to describe the degree to which the source code of a program is executed when a particular test suite runs. A higher percentage of coverage typically indicates more of the source code has been tested, which can suggest a higher level of software quality assurance.
Different coverage criteria represent the ways in which test coverage can be measured. For example, statement coverage measures whether each line of source code has been executed. Function coverage ensures that all the functions defined in the code have been called at least once. Branch coverage, also known as decision coverage, tests each possible path or branch through control structures like if-else or switch-case statements. To illustrate, consider a simple function that calculates the maximum of two numbers. Statement coverage would ensure each line in the function is executed, while branch coverage would require tests for both the case where the first number is larger and the case where the second number is larger.