Explain the concept of code coverage in Software Quality Assurance.

Code coverage is a metric used in software quality assurance to measure the extent to which the source code of a software application has been tested. It provides insights into the effectiveness of the testing process by determining the percentage of code that has been executed during testing.

The concept of code coverage revolves around the idea that thorough testing should aim to exercise all possible paths and conditions within the code. It helps identify areas of the code that have not been tested, allowing developers and testers to focus their efforts on improving test coverage in those areas.

There are different types of code coverage metrics that can be used to assess the level of testing performed. Some common types include:

1. Statement coverage: This metric measures the percentage of statements in the code that have been executed during testing. It ensures that each line of code has been executed at least once.

2. Branch coverage: Branch coverage goes a step further than statement coverage by measuring the percentage of decision points (branches) in the code that have been executed. It ensures that both true and false branches of conditional statements have been tested.

3. Path coverage: Path coverage aims to test all possible paths through the code, including different combinations of branches and loops. It ensures that all possible execution paths have been exercised.

4. Function coverage: Function coverage measures the percentage of functions or methods in the code that have been called during testing. It ensures that all functions have been tested.

Code coverage is an essential aspect of software quality assurance as it helps identify areas of the code that are prone to defects and have not been adequately tested. By analyzing code coverage reports, developers and testers can prioritize their efforts to improve test coverage in critical areas, reducing the risk of undetected bugs in the software.

However, it is important to note that achieving 100% code coverage does not guarantee the absence of defects. Code coverage is just one aspect of testing, and it should be complemented with other testing techniques such as boundary value analysis, equivalence partitioning, and error guessing to ensure comprehensive testing.