Linjedekning

Linjedekning is a software testing metric that measures the extent to which executable lines of code have been executed by a set of tests. It is typically expressed as a percentage of the total instrumented lines that were run during a test suite.

To measure linjedekning, development teams use coverage tools that instrument source code or compiled bytecode. These tools record when a line of code is executed and generate a report listing total lines, covered lines, and the resulting coverage percentage. Distinctions are often made between executable statements, non-executable lines (such as comments), and lines that are not relevant for testing. Some tools report per-file, per-function, and per-line granularity.

Interpretation and limitations: A higher linjedekning value generally indicates more code has been exercised by tests, but it does not prove correctness. It may occur without validating outcomes, and it can miss untested paths, especially in conditional branches or exception handling. It should be used in combination with other metrics like branch coverage, path coverage, and mutation testing. It can also be affected by generated or vendor code that is excluded from reports.

Applications and practices: Linjedekning is commonly used in continuous integration and quality gates to monitor test coverage over time. Teams may set targets (for example, 80–90%) and gradually increase them, while focusing on meaningful coverage rather than chasing numbers. It is language- and tool-agnostic, with many ecosystem tools available for Java, JavaScript, Python, C/C++, and other languages.