[Boost-users] how to create fixtures in unit test framework

From: eli_at_[hidden]
Date: 2004-01-25 17:19:19

Hello. In September there was a discussion of how to set up text fixtures
for unit tests and the relative merits of a setUp() tearDown() method. A
key issue that I did not see included in this discussion is how setUp()
affects the sharing of the test fixture between methods in a test class.
For example, let's say your fixture includes the setup of an object myA
as part of its fixture:

class TestFixtureA
{
  MyA myA;
  TestFixtureA(...) : myA(...){  }
  void testMethod1() { perturbWithMethod1(myA);
                      
BOOST_CHECK(somethingAbout(myA)); }
  void testMethod2() { perturbWithMethod2(myA);
                      
BOOST_CHECK(somethingElseAbout(myA); }
};

The results of testMethod2 are context sensitive: if you include
testMethod1 and testMethod2 in your suite, the results of testMethod2 can
be different than if testMethod2 were called alone. This seems to take
the unit out of unit testing, and the fix out of fixture. In other
frameworks, the behavior is that setUp() will be called independently for
each invocation of each test method. This is possibly resource intensive,
but makes for very atomic testing and I think it is essential to the unit
testing concept.

In Boost.Test, this sort of stable fixture can be obtained via Dean
Brettles suggestion by defining a setUp function in the test class: 
setUp();
shared_ptr<void> guard(static_cast<void*>(0),
bind(&Class::tearDown, this));
and calling this function from every other single test function.
This is a pain to do manually, and introduces human error issues. Dean
included a second suggestion as to how to make it part of the
framework.

I would like to second the suggestion.  I feel the constructor based
approach in Boost is excellent for parts of the fixture that are shared
for whatever reason. The framework would be more flexible, however, if
the setUp() existed to assure stable values over a test suite.

Thanks for listening,
Eli