LDRA offers a comprehensive and automated approach to achieving compliance with functional safety standards. The achievement of structural coverage analysis is a core objective of most functional safety standards. Function and call coverage feature most notably in ISO 26262.
LDRA’s Functional Coverage & Call Coverage Reports take the form of an optional module for use with the LDRA tool suite, LDRAunit, and LDRAcover.
Function coverage is a measure of the number of functions (sub-programs) that have been called during the execution of a program, as a percentage of the number of functions that exist in that program.
Call coverage is a measure of the number of calls to functions (sub-programs) that have been exercised during the execution of a program, as a percentage of the number of calls that exist in that program.
A literal interpretation of call coverage takes no account of redundant functions. By definition, these are not called at all! But redundant functions are important. They not only impact the maintenance of the code, but they are also likely to result from programming error. It is therefore wise to consider a metric alongside call coverage that will identify them – perhaps Branch/Decision Coverage or Modified Condition/Decision Coverage (MC/DC).
To evaluate the completeness of test cases and provide evidence that the test objectives for integration testing are adequately achieved, ISO 26262 requires that the structural coverage shall be assessed by the methods listed in Table 12.
ISO 26262:6 §10.4.5 recommends the use of both function coverage and call coverage for less critical applications (ASIL A & B), and highly recommends them where criticality is higher (ASIL C & D).
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