What is the code coverage in Unit Testing?

Code coverage indeed refers to the extent to which the application code is exercised by the tests during its execution. It provides insights into how much of the code is being tested and helps identify areas that may need additional testing.

Coverage criteria are commonly divided into several types:

Functional Coverage: This criterion focuses on ensuring that each function in the code is called by the test cases. It measures the ratio of the number of functions called by the tests to the total number of functions in the codebase.

Statement Coverage: Statement coverage aims to execute each statement in the code at least once during the testing process. It calculates the ratio of the number of lines executed by the tests to the total number of lines in the code.

Branch Coverage: Branch coverage requires that each control structure (e.g., if-else statements) in the code is executed both when true and when false. It ensures that all possible branches of the code are exercised by the tests.

Conditional Coverage: Conditional coverage focuses on ensuring that each conditional sub-expression within the code is evaluated as both true and false during testing. It measures the completeness of testing in terms of the conditions within statements.

It's worth noting that while some organizations or standards like #ISTQB may not distinguish between branch and conditional coverage, they serve slightly different purposes in evaluating the thoroughness of testing. Ultimately, achieving high code coverage across these criteria can help increase confidence in the reliability and quality of the software being developed.

Benefits of High Code Coverage:

Achieving high code coverage across these criteria can significantly increase confidence in the software's reliability and quality. By identifying areas with low coverage, developers can prioritize writing additional tests to ensure more comprehensive testing and a more robust codebase.