The new test is a randomized stress test. It consistently passes right
now. The test's detailed output can be analyzed to reveal anomalies and
bugs. The test can catch various bugs that future changes to
ConcurrentQueue's code may introduce.
ConcurrentQueueTest::cancelPending1UserThread() often fails when
ConcurrentQueueTest is launched from Qt Creator immediately after
switching between Debug and Release YACReader build configurations.
The CPU busyness must be affecting the thread scheduling timing, which
breaks the test's timing assumptions in this case.
Use the return value of ConcurrentQueue::cancelPending() instead of
relying on the timing of thread scheduling to determine the number of
canceled jobs.
Place common Qt Test qmake code into tests/qt_test.pri.
Build tests as part of top-level YACReader project unless no_tests
CONFIG option is set. This way the tests are built by default during
development. Packagers can skip building tests by running
`qmake "CONFIG+=no_tests"`.
Both ConcurrentQueueTest::singleUserThread() and
ConcurrentQueueTest::multipleUserThreads() pass. Evidently
ConcurrentQueue::enqueue() can be safely called from multiple threads on
the same ConcurrentQueue object with no additional synchronization. Once
each thread enqueues all its jobs, one thread can safely call waitAll().
