Add ProcessManager test stub

core-writer/test/test_ProcessManager.cpp

@@ -0,0 +1,2 @@
+#include "gtest/gtest.h"
+#include "ProcessManager.hpp"

core-writer/test/test_main.cpp

@@ -5,6 +5,7 @@
 #include "test_BufferedWriter.cpp"
 #include "test_ZmqRecvModule.cpp"
 #include "test_H5WriteModule.cpp"
+#include "test_ProcessManager.cpp"
 
 using namespace std;