ENH: add test for generated header

Tests/CustomCommand/GeneratedHeader/CMakeLists.txt

@@ -0,0 +1,10 @@
+ADD_CUSTOM_COMMAND(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/generated.h 
+  COMMAND 
+  ${CMAKE_COMMAND} ARGS -E
+  copy ${CMAKE_CURRENT_SOURCE_DIR}/generated.h.in 
+  ${CMAKE_CURRENT_BINARY_DIR}/generated.h 
+)
+
+INCLUDE_DIRECTORIES( ${CMAKE_CURRENT_BINARY_DIR})
+ADD_LIBRARY(GeneratedHeader main.cpp) 
+ 

Tests/CustomCommand/GeneratedHeader/generated.h.in

@@ -0,0 +1 @@
+//hello

Tests/CustomCommand/GeneratedHeader/main.cpp

@@ -0,0 +1,5 @@
+#include "generated.h"
+main()
+{
+  
+}