Problem: code coverage not working

Solution: build tests within cppzmq build, and add separate demo

demo/CMakeLists.txt

@@ -0,0 +1,23 @@
+cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
+
+project(cppzmq-demo CXX)
+
+find_package(cppzmq)
+
+enable_testing()
+add_executable(
+    demo
+    main.cpp
+    )
+
+target_link_libraries(
+    demo
+    libzmq
+    )
+
+add_test(
+  NAME
+    demo
+  COMMAND
+    ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}/demo
+  )

demo/main.cpp

@@ -0,0 +1,8 @@
+#include <zmq.hpp>
+
+int main(int argc, char** argv)
+{
+    zmq::context_t context;
+    
+    return 0;
+}