docs: Document OSX test crash behavior

Depending how your system is configured, running the
`test_deadlock_detection.py` integration test on OSX may result in a
dialog window warning you about a crashed or aborted Python process.
This crash is intentional, as the test introduces a deadlock and tests
whether it can be detected.  This patch documents this behavior in both
the build documentation and the test itself.

Signed-off-by: Patrick M. Niedzielski <[email protected]>

Author: pniedzielski

docs/BUILD.md

@@ -45,6 +45,12 @@ make test-install
 BMQ_BROKER_URI=tcp://localhost:30114 make check
 ```
 
+Note that on OSX, the
+`tests/integration/test_deadlock_detection.py::test_deadlock_detection_warning`
+test may display a dialog warning you of a crashed Python process,
+depending on your system configuration.  This crash is intentional, and
+is part of the test.
+
 Additional `make` targets are provided, such as for test coverage.
 Dependencies for these can be installed as follows:
 

tests/integration/test_deadlock_detection.py

@@ -13,6 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# N.B. On OSX, the
+# `tests/integration/test_deadlock_detection.py::test_deadlock_detection_warning`
+# test may display a dialog warning you of a crashed Python process, depending
+# on your system configuration.  This crash is intentional, and is part of the
+# test.
+
 import signal
 import subprocess
 import sys