Given the documented behavior of bounded_channel(hwm, lwm), it follows that
bounded_channel(n, n) is invalid.
If the number of items in the channel == hwm, a push will block.
But if the number of items in the channel <= lwm, a push will succeed without
blocking.
Therefore, setting hwm == lwm results in a contradiction.
We intend to document that bounded_channel(hwm) is equivalent to
bounded_channel(hwm, (hwm-1)). That may or may not simplify the code, but it
certainly simplifies the reader's mental model of the relationship between the
two constructors.
However, that assertion requires that for bounded_channel(hwm), lower_bound()
in fact return (hwm-1). Test for that.
Also use BOOST_CHECK_EQUAL(a, b) instead of BOOST_CHECK(a == b) where
applicable, since the former is more informative when the test fails.
Sadly, tests on channel_op_status must still use BOOST_CHECK(a == b) --
apparently because channel_op_status, as an enum class, cannot be streamed to
std::ostream?
