Add unit tests for allocation errors

[gavv]

Many pipeline elements take core::IArena as an argument and perform some allocations in constructor. If allocations fails, the convention is to report error (StatusNoMem) via init_status() method.

We need to cover this behavior with unit tests. For each element, we need to add one test that creates the element using mock, which always fails (e.g. core::NoopArena). Then we should check that the element returned StatusNoMem via init_status().

Elements to cover:

• ChannelMapperReader
• ChannelMapperWriter
• PcmMapperReader
• PcmMapperWriter
• ProfilingReader
• ProfilingWriter
• Mixer

[KBoumghar]

Hey, willing to help for this, but I'm new to the project so I'm a bit lost (bear with me please :) ). Let's take ChannelMapperReader for example, from what I understand, we'd want something like :

TEST(channel_mapper_reader, empty_allocation) {
    enum { FrameSz = MaxSz / 2 };

    const SampleSpec in_spec(MaxSz, Sample_RawFormat, ChanLayout_Surround,
                             ChanOrder_Smpte, ChanMask_Surround_Mono);
    const SampleSpec out_spec(MaxSz, Sample_RawFormat, ChanLayout_Surround,
                              ChanOrder_Smpte, ChanMask_Surround_Stereo);

    const core::nanoseconds_t start_ts = 1000000;

    test::MockReader mock_reader;
    ChannelMapperReader mapper_reader(mock_reader, core::NoopArena, in_spec, out_spec);
    
    //Somehow check here if mapper_reader here has StatusNoMem
}

couple questions :

1. Is the "signature" for TEST good (well I'm guessing empty_allocation is not a super good name)? I'm not exactly sure how TEST is called and my only experience with tests in C++ comes from using GTest. From reading a bit it seems to be first argument is the "object" it's testing and second is what it's testing, but just wanted to make sure.

2. I tried grepping for init_status in the repo, but couldn't find it. Grepping for StatusNoMem and looking at other tests, it seems like they're getting a status out of some methods (e.g. meter.write()) and then doing a LONGS_EQUAL to compare that to StatusNoMem. We also have the is_valid(), but that's not the status being talked about in your message, but seems like other use of core::NoopArena just check for that.

What I'm guessing here is that the test is on another "level" (not the components themselves) and I'm missing something / reading what you wrote wrongly. Any pointers would be appreciated :) !