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3<TITLE>Boost Test Library generic recommendations</TITLE>
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10<DIV class="header"> <A href="../index.html">Boost.Test</A> > <A href="recomendations.html"> Usage
11    recommendations </A> > <SPAN class="current_article"> Generic</SPAN></DIV> 
12<DIV class="body"> <IMG src='../btl1.gif' width='252' height='43' alt="Boost Test logo"> 
13  <H1 class="subtitle"><SPAN class="first-line-indented">Generic</SPAN> usage
14    recommendations</H1> 
15  <UL> 
16    <LI><A href="#t2">Prefer the unit test framework to the test execution monitor</A></LI> 
17    <LI><A href="#t3">Prefer offline compiled libraries to the inline included
18        components</A> </LI> 
19    <LI><A href="#t4">If you use only free function based test cases advance
20        to the automatic registration facility</A> </LI> 
21    <LI><A href="#t1">To find location of first error reported by test tool within
22        reused template function, use special hook within framework headers</A></LI> 
23    <LI><A href="#t5">To test reusable template base component with different
24        template parameter use test case template facility</A></LI> 
25    <LI><A href="#t6">Prefer BOOST_CHECK_EQUAL to BOOST_CHECK</A></LI> 
26  </UL> 
27  <H5>Prefer the unit test framework to the test execution monitor<A name="t2"></A> </H5> 
28  <P class="first-line-indented">In most cases when you start working on unit
29    test you have a choice to use either one of the components provided by the
30    Boost.Test. Even though in simple cases test cases based solution would be
31    couple lines longer in a long term I would opt to use unit test framework.
32    At some point you will anyway end up with code like this:</P> 
33  <PRE class="code"><SPAN class="cpp-type">void</SPAN> test_feature1()
34{
35    ...
36
37}
38
39
40<SPAN class="cpp-type">int</SPAN> test_main()
41
42{
43
44    test_feature1();
45    test_feature1();
46    ...
47    test_featureN();           
48}</PRE> 
49  <P class="first-line-indented">Why then not switch to test cases? In code like
50    above if any exception occurred in test_feature1() rest of test is skipped.
51    While with test cases each separate feature test is executed and monitored
52    separately and you are getting more from your test. </P> 
53  <H5>Prefer offline compiled libraries to the inline included components <A name="t3"></A></H5> 
54  <P class="first-line-indented">If you are just want to write quick simple test
55    in environment where you never used Boost.Test before - yes, use included
56    components. But if you plan to use Boost.Test on permanent basis, small investment
57    of time needed to build (if not build yet), install and change you makefiles/project
58    settings will soon return to you in a form of shorter compilation time. Why
59    do you need to make your compiler do the same work over and over again? </P> 
60  <H5>If you use only free function based test cases advance to the automatic
61    registration facility<A name="t4"></A></H5> 
62  <P class="first-line-indented">It's really easy to switch to automatic registration.
63    And you don't need to worry about forgotten test case anymore.</P> 
64  <H5>To find location of first error reported by test tool within reused template
65    function, use special hook within framework headers<A name="t1"></A> </H5> 
66  <P>In some cases you are reusing the same template based code from within one
67    test case (actually I recommend better solution in such case- see below).
68    Now if an error gets reported by the test tool within that reused code you
69    may have difficulty locating were exactly error occurred. To address this
70    issue you could either a add BOOST_MESSAGE statements in templated code that
71    log current type id od template parameters or you could use special hook
72    located in unit_test_result.hpp called first_failed_assertion(). If you set
73    a breakpoint right on the line where this function is defined you will be
74    able to unroll the stack and see where error actually occurred.</P> 
75  <H5>To test reusable template base component with different template parameter
76    use test case template facility<A name="t5"></A></H5> 
77  <P class="first-line-indented">If you writing unit test for generic reusable
78    component you may have a need to test it against set of different template
79    parameter types . Most probably you will end up with a code like this:</P> 
80  <PRE class="code"><SPAN class="reserv-word">template</SPAN>&lt;<SPAN class="reserv-word">typename</SPAN> TestType&gt;
81<SPAN class="cpp-type">void</SPAN>
82specific_type_test( TestType* = <SPAN class="literal">0</SPAN> )
83{
84    MyComponent&lt;TestType&gt; c;
85    ... <SPAN class="comment">// here we perform actual testing</SPAN>
86}
87
88
89<SPAN class="cpp-type">void</SPAN> my_component_test()
90{
91    specific_type_test( (<SPAN class="cpp-type">int</SPAN>*)<SPAN class="literal">0</SPAN> );
92    specific_type_test( (<SPAN class="cpp-type">float</SPAN>*)<SPAN class="literal">0</SPAN> );
93    specific_type_test( (UDT*)<SPAN class="literal">0</SPAN> );
94    ...
95}
96</PRE> 
97  <P class="first-line-indented">This is namely the situation where you would
98    use test case template facility. It's not only simplify this kind of unit
99    testing by automating some of the work, in addition every argument type gets
100    tested separately under unit test monitor. As a result if one of types produce
101    exception or non-fatal error you may still continue and get results from
102    testing with other types. </P> 
103  <H5>Prefer BOOST_CHECK_EQUAL to BOOST_CHECK<A name="t6"></A></H5> 
104  <P class="first-line-indented">Even though BOOSK_CHECK tool is most generic
105    and allows to validate any bool convertible expression, I would recommend
106    to use, if possible, more specific tools dedicated to the task. For example
107    if you need you validate some variable vs. some expected value use BOOST_CHECK_EQUAL
108    instead. The main advantage is that in case of failure you will see the mismatched
109    value - the information most useful for error identification. The same applies
110    to other tools supplied by the framework. </P> 
111</DIV> 
112<DIV class="footer"> 
113  <DIV class="footer-body"> 
114    <P> &copy <A name="Copyright">Copyright</A> <A href='mailto:boost-test at emailaccount dot com (please unobscure)'>Gennadiy
115        Rozental</A> 2001-2005. <BR> 
116      Distributed under the Boost Software License, Version 1.0.
117      (See accompanying file <A href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</A> or
118      copy at <A href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</A>)</P> 
119    <P>Revised:
120      <!-- #BeginDate format:Sw1 -->26 January, 2004<!-- #EndDate --> 
121    </P> 
122  </DIV> 
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