Block coverage
Code Coverage for C
When running the Code Coverage feature on C source code, HCL OneTest™ Embedded can provide the following coverage types for code blocks:
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Statement Blocks
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Statement Blocks and Decisions
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Statement Blocks, Decisions, and Loops
Statement Blocks (or Simple Blocks)
Simple blocks are the C function main blocks, blocks introduced by decision instructions:
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THEN and ELSE FOR IF
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FOR, WHILE and DO ... WHILE blocks
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non-empty blocks introduced by switch case or default statements
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true and false outcomes of ternary expressions (<expr> ? <expr> : <expr>)
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blocks following a potentially terminal statement.
/* Power_of_10 Function */ /* -block */
int power_of_10 ( int value, int max )
{
int retval = value, i;
if ( value == 0 ) return 0; /* potentially terminal statement */
for ( i = 0; i < 10; i++ ) /* start of a sequence block */
{
retval = ( max / 10 ) < retval ? retval * 10 : max;
}
return retval;
} /* The power_of_10 function has 6 blocks */
/* Near_color function */
ColorType near_color ( ColorType color )
{
switch ( color )
{
case WHITE :
case LIGHT_GRAY :
return WHITE;
case RED :
case PINK :
case BURGUNDY :
return RED;
/* etc ... */
}
} /* The near_color function has at least 3 simple blocks */
Each simple block is a branch. Every C function contains at least one simple block corresponding to its main body.
Decisions (Implicit Blocks)
Implicit blocks are introduced by an IF statement without an ELSE or a SWITCH statement without a DEFAULT.
/* Power_of_10 function */
/* -block=decision */
int power_of_10 ( int value, int max )
{
int retval = value, i;
if ( value == 0 ) return 0; else ;
for (i =0;i <10;i++)
{
retval = ( max / 10 ) < retval ? retval * 10 : max;
}
return retval;
}
/* Near_color function */
ColorType near_color ( ColorType color )
{
switch ( color )
{
case WHITE :
case LIGHT_GRAY :
return WHITE;
case RED :
case PINK :
case BURGUNDY :
return RED;
/* etc ... with no default */
default : ;
}
}
Each implicit block represents a branch.
Because the sum of all possible decision paths includes implicit blocks as well as statement blocks, reports provide the total number of simple and implicit blocks as a figure and as a percentage. Code Coverage places this information in the Decisions report.
Loops (Logical Blocks)
A typical FOR or WHILE loop can reach three different conditions:
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The statement block contained within the loop is executed zero times, therefore the output condition is True from the start
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The statement block is executed exactly once, the output condition is False, then True the next time
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The statement block is executed at least twice. (The output condition is False at least twice, and becomes True at the end)
In a DO...WHILE loop, because the output condition is tested after the block has been executed, two further branches are created:
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The statement block is executed exactly once. The output is condition True the first time.
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The statement block is executed at least twice. (The output condition is False at least once, then true at the end)
In this example, the function try_five_times ( ) must run several times to completely cover the three logical blocks included in the WHILE loop:
/* Try_five_times function */
/* -block=logical */
int try_five_times ( void )
{
int result,i =0;
/*try ()is afunction whose return value depends
on the availability of a system resource, for example */
while ( ( ( result = try ())!=0 )&&
(++i <5 ));
return result;
} /* 3 logical blocks */
Related Topics
Selecting Coverage Types | About Code Coverage | Code Coverage settings