About types of code coverage

Code coverage

Summary of this article

This article describes the following three types of coverage.

--Statement coverage (C0: instruction coverage) --Branch coverage (C1: branch coverage) --Simple condition coverage (C2: condition coverage)

Sample code used in the explanation

 if (Conditional statement a1||Conditional statement a2) {　//Judgment condition A

Statement 1 } else{ Statement 2

} if (conditional statement b1 && conditional statement b2) {// Judgment condition B Statement 3 }

Statement coverage (C0: instruction coverage)

Conclusion

--The percentage of executable statements (instructions) that were executed in the test **
⇒ For 100% coverage, all executable statements must be executed at least once

In the case of the above sample code

--Three test cases are required to execute statements 1 to 3

Branch coverage (C1: branch coverage)

Conclusion

--Of all the judgment conditions, ** the ratio of judgment conditions executed in the test **
⇒ In order to achieve 100% coverage, it is necessary to execute the truth of each judgment condition at least once.

In the case of the above sample code

--The following two test cases are required (* It can be confirmed that the truth of each judgment condition is executed at least once)

1. Judgment condition A: True, Judgment condition B: False
2. Judgment condition A: False, Judgment condition B: True

Simple condition coverage (C2: condition coverage)

Conclusion

――Of all the conditional statements, ** the ratio of the conditional statements executed in the test **
⇒ In order to achieve 100% coverage, the truth of each conditional statement must be executed at least once.

In the case of the above sample code

--The following two test cases are required (it can be confirmed that the truth of each conditional statement has been executed at least once)

1. Conditional statement a1: true, conditional statement a2: false, conditional statement b1: true, conditional statement b2: true
   → Judgment condition A: ** True **, Judgment condition B: True
2. Conditional statement a1: False, Conditional statement a2: True, Conditional statement b1: False, Conditional statement b2: False
   → Judgment condition A: ** True **, Judgment condition B: False

――In addition, even if the coverage of C2 is 100% as in the above example, the coverage of C0 and C1 is not always 100%.

reference

-About coverage (C0 / C1 / C2 / MCC) in white-box testing -What is coverage analysis