Re: [Boost-users] Boost.Test BOOST_TEST/BOOST_REQUIRE_MESSAGE message arg problems

Subject: Re: [Boost-users] Boost.Test BOOST_TEST/BOOST_REQUIRE_MESSAGE message arg problems
From: Raffi Enficiaud (raffi.enficiaud_at_[hidden])
Date: 2018-08-24 14:14:05

On 18.08.18 20:51, Olaf Peter via Boost-users wrote:
> Am 18.08.2018 um 20:38 schrieb Olaf Peter via Boost-users:
>>
>>>> OK, my test_observer_fixture with overloads is ready:
>>>>
>>>> class test_observer_fixture
>>>> {
>>>> Â Â Â Â  struct test_observer : public utf::test_observer
>>>> Â Â Â Â  {
>>>> Â Â Â Â  Â Â Â  virtual void test_unit_aborted(utf::test_unit const& tu) 
>>>> override;
>>>> Â Â Â Â  Â Â Â  virtual void assertion_result(utf::assertion_result result) 
>>>> override;
>>>> Â Â Â Â  Â Â Â  // are the others required for my use case?
>>>> Â Â Â Â  };
>>>>
>>>> Â Â Â Â  test_observer observer;
>>>>
>>>> public:
>>>> Â Â Â Â  test_observer_fixture();
>>>> Â Â Â Â  ~test_observer_fixture();
>>>>
>>>> public:
>>>> Â Â Â Â  void setup();
>>>> Â Â Â Â  void teardown();
>>>> };
>>>>
>>>> and get called by my BOOST_DATA_TEST_CASE. What is the prefered way 
>>>> to use this Fixture to save the test result in case of failure/abort?
>>>>
>>>>
>>>> BOOST_DATA_TEST_CASE( wave,
>>>> Â Â Â Â  utf_data::make_delayed<testsuite::dataset_loader>( 
>>>> "test_case/wave" ),
>>>> Â Â Â Â  input, expected, orig_file_name)
>>>> {
>>>> Â Â Â  ...
>>>> Â Â Â Â  auto [parse_ok, parse_result] = parse(input, parser, 
>>>> test_case_name);
>>>>
>>>> Â Â Â Â  BOOST_REQUIRE(parse_ok);
>>>>
>>>> Â Â Â Â  BOOST_TEST(parse_result == expected, btt::per_element());
>>>>
>>>> Â Â Â Â Â Â Â  ??? my_diagnostic_saving .... (orig_file_name, input, 
>>>> parse_result);
>>>> Â Â Â Â  );
>>>> }
>>>>
>>>> Thanks,
>>>> Olaf
>>>
>>> Sorry for the late answer,
>>>
>>> In the teardown, you may check if the current test had failures. You 
>>> can do so by accessing the global singleton "results_collector". If 
>>> "tc" is the current test case (that you can get with 
>>> "current_test_case"):
>>>
>>> test_results const& tr = results_collector.results( tc.p_id );
>>>
>>> will give you the result.
>>>
>>> If the fixture should be applied to each of the test case inside your 
>>> suite, you can install it like this:
>>>
>>> https://www.boost.org/doc/libs/1_67_0/libs/test/doc/html/boost_test/tests_organization/fixtures/case.html#boost_test.tests_organization.fixtures.case.fixture_for_a_complete_subtree 
>>>
>>>
>>> Accessing via the test result will let you check if this is a failure 
>>> or an abort: the BOOST_TEST_REQUIRE (BOOST_REQUIRE is deprecated) 
>>> will fire an abort if I remember well. Using this way to install the 
>>> fixture will also let you access the instance of the fixture directly 
>>> (see examples in the documentation).
>>>
>> Since my global testobserver works for all events which may interested 
>> even in the future (e.g exceptions), I have problems to apply them in 
>> my use case.
>>
>> I've added a member function to my testobserer fixture
>>
>> void test_obserer_fixture::failure_diagnostic(std::string const&, 
>> ...)Â  which I can activate on failed tests using the events I've got 
>> from utf::observer::assertion_result()
>>
>> Now, in file test_main.cpp I have:
>> -----------------------------------------
>> #define BOOST_TEST_MODULE "Test Suite"
>> #include <boost/test/included/unit_test.hpp>
>> #include <testsuite/test_observer_fixture.hpp>
>>
>> using test_observer_fixture = testsuite::test_observer_fixture;
>> BOOST_TEST_GLOBAL_FIXTURE(test_observer_fixture);
>> -----------------------------------------
>>
>> and in (I have several)Â  concrete test case file:
>> ------------------------------------------
>> #include <boost/test/unit_test.hpp>
>> #include <boost/test/output_test_stream.hpp>
>> #include <testsuite/test_observer_fixture.hpp>
>> ...
>> BOOST_AUTO_TEST_SUITE( my_testsuite )
>>
>> BOOST_DATA_TEST_CASE( failure_test,...
>> Â Â Â  ...,
>> Â Â Â  input, expected, test_case_name)
>> {
>> ...
>> }
>> -------------------------------------------
>>
>> and I can see/log:
>> # assertion failed: failure_test/test_case/_0
>>
>> But how to access the global fixture now?
>>
>> I've changed the test case to:
>> ------------------------------------------
>> ...
>> BOOST_DATA_TEST_CASE_F(test_observer_fixture, failure_test,
>> Â Â Â  ...,
>> Â Â Â  input, expected, test_case_name)
>> {
>> Â Â Â  ...
>> Â Â Â  failure_diagnostic(...);
>> }
>> -------------------------------------------
>>
>>
>> Boost.Test ships a BOOST_DATA_TEST_CASE_F() macro for this case, which 
>> is a 'local' fixture, each time constructed and destroyed which is 
>> expensive - so  I like the idea of a global fixture to save to 
>> filesystem. Even I've installed it as global one too the events are 
>> doubled... but I can see that the test observer shows the test status 
>> followed by the call to failure_diagnostic - so the concept works.
>>
>> To reduce it: How can I access a member function of global fixture on 
>> a compilation unit layout shown above.
> even the use of
> 
> BOOST_FIXTURE_TEST_SUITE( my_testsuite, test_observer_fixture )
> 
> seems to create/destroy the fixture for each test case.

This one:
https://www.boost.org/doc/libs/1_68_0/libs/test/doc/html/boost_test/tests_organization/fixtures/per_test_suite_fixture.html

does it once per test suite. However it is isolated from the test case.

The fact that a test case body can access the fixture is not a very good 
pattern and has several caveats (although very convenient). For 
instance, as you can observe, global fixtures and test case/suite 
fixtures do not have the same isolation.

If you want to access the global fixture, you have to expose your 
fixture globally, provide some static member function that return a 
pointer to a singleton. The test framework itself will not create more 
than one instance.

But I am a bit lost in what you are doing, and to me this does not go to 
the right direction. If the test module is very complicated to maintain, 
it reduces the chances to be useful, steady and stable on the long run.

When I look back, I can see one of the comment in the code that says:

     // call diagnostic only in failure case and write then

This means to me that a fixture should be executed for each test case. 
The purpose of the fixture would be to write the diagnostic in case of a 
failure.

Does this only work for you?

Best,
Raffi