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| <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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