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<div class="titlepage"><div><div><h4 class="title">
<a name="utf.user-guide.fixture"></a>Fixtures or let me repeat myself</h4></div></div></div>
<p class="first-line-indented">
In general terms a test fixture or test context is the collection of one or more of the following items, required
to perform the test:
</p>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="itemizedlist"><ul type="disc">
<li>preconditions</li>
<li>particular states of tested unites</li>
<li>necessary cleanup procedures</li>
</ul></div>
<p class="first-line-indented">
Though these tasks are encountered in many if not all test cases, what makes a test fixture different is
repetition. Where a normal test case implementation does all preparatory and cleanup work itself, a test fixture
allows this to be implemented in a separate reusable unit.
</p>
<p class="first-line-indented">
With introduction of extreme programming (XP), the testing style, that require test setup/cleanup repetition, is
becoming more and more popular. Single XP adopted test modules may contain hundreds of single assertion test cases,
many requiring very similar test setup/cleanup. This is the problem that the test fixture is designed to solve.
</p>
<p class="first-line-indented">
In practice a test fixture usually is a combination of setup and teardown functions, associated with test case.
The former serves the purposes of test setup; the later is dedicated to the cleanup tasks. Ideally it's
preferable that a test module author is able to define variables used in fixtures on the stack and the same time
is able to refer to them directly in test case.
</p>
<p class="first-line-indented">
It's important to understand that C++ provides a way to implement a straightforward test fixture solution
that almost satisfies our requirements without any extra support from the test framework. This may explain why
test fixtures support was introduced in the <acronym class="acronym">UTF</acronym> somewhat late in its life cycle. Here is how simple test module
with such a fixture may look like:
</p>
<pre class="programlisting">struct MyFixture {
MyFixture() { i = new int; *i = 0 }
~ MyFixture() { delete i; }
int* i;
};
BOOST_AUTO_TEST_CASE( test_case1 )
{
MyFixture f;
// do something involving f.i
}
BOOST_AUTO_TEST_CASE( test_case2 )
{
MyFixture f;
// do something involving f.i
}
</pre>
<p class="first-line-indented">
This is a generic solution that can be used to implement any kind of shared setup or cleanup procedure. Still
there are several more or less minor practical issues with this pure C++ based fixtures solution:
</p>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="itemizedlist"><ul type="disc">
<li>
We need to add a fixture declaration statement into each test case manually.
</li>
<li>
Objects defined in fixture are references with "<fixture-instance-name>." prefix.
</li>
<li>
There is no place to execute a "global" fixture, which performs "global" setup/cleanup
procedures before and after testing.
</li>
</ul></div>
<p class="first-line-indented">
While there is little the <acronym class="acronym">UTF</acronym> can do to address these issues for manually registered test units, it's
possible to resolve them for test units that are automatically registered. To do this the <acronym class="acronym">UTF</acronym> defines a
<a class="link" href="fixture/model.html" title="Generic fixture model">generic fixture model</a> - fixed interfaces that both setup and
teardown fixture functions should comply to. Based on the generic fixture model, the <acronym class="acronym">UTF</acronym> presents solution for
the following tasks:
</p>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="itemizedlist"><ul type="disc">
<li><a class="link" href="fixture/per-test-case.html" title="Per test case fixture">per test case fixture automation</a></li>
<li><a class="link" href="fixture/test-suite-shared.html" title="Test suite level fixture">shared test suite level fixture</a></li>
<li><a class="link" href="fixture/global.html" title="Global fixture">"global" fixture support</a></li>
</ul></div>
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<td align="right"><div class="copyright-footer">Copyright 2001-2007 Gennadiy Rozental</div></td>
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