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0 pointssmarx0074mo ago0 comments

Modified Condition/Decision Coverage (MC/DC) is a test coverage approach that considers a chunk of code covered if:

- Every branch was "visited". Plain coverage already ensures that. I would actually advocate for 100% branch coverage before 100% line coverage.

- Every part (condition) of a branch clause has taken all possible values. If you have if(enabled && limit > 0), MC/DC requires you to test with enabled, !enabled, limit >0, limit <=0.

- Every change to the condition was shown to somehow change the outcome. (false && limit > 0) would not pass this, a change to the limit would not affect the outcome - the decision is always false. But @zweifuss has a better example.

- And, of course, every possible decision (the outcome of the entire 'enabled && limit > 0') needs to be tested. This is what ensures that every branch is taken for if statements, but also for switch statements that they are exhaustive etc.

MC/DC is usually required for all safety-critical code as per NASA, ESA, automotive (ISO 26262) and industrial (IEC 61508).

0 comments

amarant4mo ago

Limit <=0 appears to include every number between 0 and INT_MIN.

I hope you don't have any string inputs, or your test is gonna take a while to run!

smarx007OP4mo ago

To test 'limit > 0' according to MC/DC, you need only two values, e.g. -1 and 1. There may be other code inside the branch using limit in some other ways, prompting more test cases and more values of limit but this one only needs two.

But yes, exhaustively testing your code is a bit exhausting ;)

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