Boost Unit Test: Catch an unsuccessful Test

Question

I am running a test where a usb device is opened, a packet is sent and received and it is closed again. It looks like this:

void TestCase1(void) { int recv; BOOST_REQUIRE(initDevice()); BOOST_REQUIRE(openDevice()); BOOST_REQUIRE_EQUAL(receiveData(), 5); BOOST_REQUIRE(closeDevice()); BOOST_REQUIRE(uninitDevice()); }

Now whenever there is an error in the receiveData() call and the Check for '5' fails, the closeDevice() and uninitDevice() are not called anymore and I cannot use the device in the next test. Is there a way to handle this? Maybe catch an exception and close and uninit the device in that catch scope too? Or is this a complete wrong approach? I am pretty new to unit testing. So any help is appreciated. Thanks!

is opening actual usb ports a sensible thing to do in a unit test? — doctorlove
– doctorlove, Commented Oct 10, 2013 at 14:37

Glorfindel · Accepted Answer · 2022-06-24 19:01:13Z

I would use one of the key concepts within modern C++, RAII, to help keep initDevice / uninitDevice and openDevice/closeDevice tied together:

class USBDeviceHandler { public: USBDeviceHandler() : initDeviceHandle { ::initDevice()), &::uninitDevice }, openDeviceHandle { ::openDevice()), &::closeDevice } { } using init_handle = std::unique_ptr<void, decltype(&::uninitDevice)>; using open_handle = std::unique_ptr<void, decltype(&::closeDevice)>; init_handle initDeviceHandle; open_handle openDeviceHandle; }; void TestCase1(void) { int recv; USBDeviceHandler device; //init/open is called upon construction BOOST_REQUIRE_EQUAL(receiveData(), 5); }//close/uninit is called upon destruction

This is based off the example given in Rule of Zero.

Is USBWrapper supposed to be the constructor for USBDeviceHandler?
@doctorlove - oops, fixed. I changed the name of the helper class halfway through writing the answer.

John Zwinck · Accepted Answer · 2013-10-10 14:15:53Z

You should use BOOST_CHECK and BOOST_CHECK_EQUAL when you want to report a condition not being satisfied, yet still continue the test. In this case, perhaps the first two items should be "REQUIRE"d, and the last three should be "CHECK"ed.

doctorlove · Accepted Answer · 2013-10-10 14:34:55Z

You might be better off doing things that must happen first in a fixture setup and tidying up in a tear down function. Obviously using OO with RAII and putting the receiveData as a class method would avoid this.
Alternatively, BOOST_CHECK will check the condition and continue the test if it fails which would avoid the problem you have wherein BOOST_REQUIRE stops the rest of the test executing.

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