branchpeitto

Branchpeitto, commonly rendered as branch coverage, is a software testing metric that evaluates whether all possible branches of a program’s control flow have been executed at least once by a test suite. It is a form of code coverage that complements statement coverage by focusing on decision points such as if statements, switch cases, and loop conditions.

Measurement of branchpeitto involves instrumenting the code to record each outgoing path from a decision point. Branch coverage is calculated as the number of executed branches divided by the total number of branches in the program’s control flow graph, typically expressed as a percentage. For an if (A) { ... } else { ... } statement, there are two branches: the true path and the false path; achieving 100% branch coverage requires tests that exercise both outcomes. With more complex expressions and nested decisions, multiple branches exist at various points in the code.

Branchpeitto is related to other coverage metrics. It generally yields higher coverage than statement coverage, since it accounts for the outcomes of decisions rather than just executed lines. Path coverage aims to exercise all possible execution paths, which is more comprehensive but often impractical for larger systems. Modified Condition/Decision Coverage (MC/DC) is a stricter form used in safety-critical domains and can require demonstrating that each condition in a decision independently affects the outcome.

Limitations of branchpeitto include that full branch coverage does not guarantee the absence of defects, particularly those arising from data values or interactions across multiple decisions. It can also be expensive to achieve in large codebases, and unreachable branches can distort the metric. Tools across languages support branch coverage as part of broader code-coverage analysis.