Test with debug build of Python when DEBUG=1 on Travis

.travis.yml

@@ -147,9 +147,13 @@ install:
 - |
   # Install dependencies
   if [ -n "$DOCKER" ]; then
+    if [ -n "$DEBUG" ]; then
+      PY_DEBUG="python$PY-dbg python$PY-scipy-dbg"
+      export CMAKE_EXTRA_ARGS="${CMAKE_EXTRA_ARGS} -DPYTHON_EXECUTABLE=/usr/bin/python${PYTHON}dm"
+    fi
     docker exec --tty "$containerid" sh -c "for s in 0 15; do sleep \$s; \
       apt-get -qy --no-install-recommends $APT_GET_EXTRA install \
-        python$PY-dev python$PY-pytest python$PY-scipy \
+        $PY_DEBUG python$PY-dev python$PY-pytest python$PY-scipy \
         libeigen3-dev cmake make ${COMPILER_PACKAGES} && break; done"
   else
     pip install numpy scipy pytest

tests/CMakeLists.txt

@@ -159,7 +159,7 @@ if(NOT PYBIND11_PYTEST_FOUND)
 endif()
 
 # A single command to compile and run the tests
-add_custom_target(pytest COMMAND ${PYTHON_EXECUTABLE} -m pytest -rws ${PYBIND11_PYTEST_FILES}
+add_custom_target(pytest COMMAND ${PYTHON_EXECUTABLE} -m pytest -rws --capture=sys ${PYBIND11_PYTEST_FILES}
                   DEPENDS pybind11_tests WORKING_DIRECTORY ${testdir})
 
 if(PYBIND11_TEST_OVERRIDE)

tests/test_cmake_build/installed_target/CMakeLists.txt

@@ -14,5 +14,9 @@ target_link_libraries(test_cmake_build PRIVATE pybind11::module)
 set_target_properties(test_cmake_build PROPERTIES PREFIX "${PYTHON_MODULE_PREFIX}"
                                                   SUFFIX "${PYTHON_MODULE_EXTENSION}")
 
+# Do not treat includes from IMPORTED target as SYSTEM (Python headers in pybind11::module).
+# This may be needed to resolve header conflicts, e.g. between Python release and debug headers.
+set_target_properties(test_cmake_build PROPERTIES NO_SYSTEM_FROM_IMPORTED ON)
+
 add_custom_target(check ${CMAKE_COMMAND} -E env PYTHONPATH=$<TARGET_FILE_DIR:test_cmake_build>
                   ${PYTHON_EXECUTABLE} ${PROJECT_SOURCE_DIR}/../test.py ${PROJECT_NAME})