Editing Code coverage (section)

=== Basic coverage criteria ===
There are a number of coverage criteria, but the main ones are:<ref>{{cite book | author=Glenford J. Myers | title=The Art of Software Testing, 2nd edition |publisher=Wiley | year=2004| isbn=0-471-46912-2}}</ref>
* '''Function coverage'''{{snd}}has each function (or [[subroutine]]) in the program been called?
* '''Statement coverage'''{{snd}}has each [[statement (computer science)|statement]] in the program been executed?
* '''Edge coverage'''{{snd}}has every [[Graph theory|edge]] in the [[control-flow graph]] been executed?
** '''Branch coverage'''{{snd}}has each branch (also called the [[DD-path]]) of each control structure (such as in [[Conditional (programming)|''if'' and ''case'' statements]]) been executed? For example, given an ''if'' statement, have both the ''true'' and ''false'' branches been executed? (This is a subset of edge coverage'''.''')
* '''Condition coverage'''{{snd}}has each Boolean sub-expression evaluated both to true and false? (Also called predicate coverage.)

For example, consider the following [[C (programming language)|C]] function:
<syntaxhighlight lang="cpp">
int foo (int x, int y)
{
    int z = 0;
    if ((x > 0) && (y > 0))
    {
        z = x;
    }
    return z;
}
</syntaxhighlight>

Assume this function is a part of some bigger program and this program was run with some test suite. 
* ''Function coverage'' will be satisfied if, during this execution, the function <code>foo</code> was called at least once.
* ''Statement coverage'' for this function will be satisfied if it was called for example as <code>foo(1,1)</code>, because in this case, every line in the function would be executed—including <code>z = x;</code>.
* ''Branch coverage'' will be satisfied by tests calling <code>foo(1,1)</code> and <code>foo(0,1)</code> because, in the first case, both <code>if</code> conditions are met and <code>z = x;</code> is executed, while in the second case, the first condition, <code>(x>0)</code>, is not satisfied, which prevents the execution of <code>z = x;</code>.  
* ''Condition coverage'' will be satisfied with tests that call <code>foo(1,0)</code>, <code>foo(0,1)</code>, and <code>foo(1,1)</code>. These are necessary because in the first case, <code>(x>0)</code> is evaluated to <code>true</code>, while in the second, it is evaluated to <code>false</code>. At the same time, the first case makes <code>(y>0)</code> <code>false</code>, the second case does not evaluate <code>(y>0)</code> (because of the lazy-evaluation of the Boolean operator), the third case makes it <code>true</code>.

In programming languages that do not perform [[short-circuit evaluation]], condition coverage does not necessarily imply branch coverage. For example, consider the following [[Pascal (programming language)|Pascal]] code fragment:
<syntaxhighlight lang="pascal">
if a and b then
</syntaxhighlight>
Condition coverage can be satisfied by two tests:
* <code>a=true</code>, <code>b=false</code>
* <code>a=false</code>, <code>b=true</code>
However, this set of tests does not satisfy branch coverage since neither case will meet the <code>if</code> condition.

[[Fault injection]] may be necessary to ensure that all conditions and branches of [[exception handling|exception-handling]] code have adequate coverage during testing.