Cmake docbook tests: Add jing.jar to test created docbook files

Usefull only if tested with data from repository.
This means: The file 'jing.jar' is not part of the distribution.

development/autotests/ExportTests.cmake

@@ -28,6 +28,13 @@
 
 find_package(Perl)
 find_program(XMLLINT_EXECUTABLE xmllint)
+find_program(JAVA_EXECUTABLE java)
+set(jingjava)
+if (JAVA_EXECUTABLE)
+  if (EXISTS "${TOP_SRC_DIR}/development/tools/jing.jar")
+    set(jingjava ${JAVA_EXECUTABLE})
+  endif()
+endif()
 
 if(PERL_FOUND)
   set(DVI_FORMATS "dvi" "dvi3")
@@ -475,6 +482,7 @@ foreach(libsubfolderx autotests/export lib/doc lib/examples lib/templates lib/ta
               "-DIgnoreErrorMessage=${missingLabels}"
               -DPERL_EXECUTABLE=${PERL_EXECUTABLE}
               -DXMLLINT_EXECUTABLE=${XMLLINT_EXECUTABLE}
+              -DJAVA_EXECUTABLE=${jingjava}
               -DENCODING=${_enc2}
               -P "${TOP_SRC_DIR}/development/autotests/export.cmake")
             setmarkedtestlabel(${TestName} ${mytestlabel}) # check for suspended pdf/dvi exports

development/autotests/export.cmake

@@ -27,6 +27,7 @@
 #       -DIgnoreErrorMessage=(ON/OFF) \
 #       -DPERL_EXECUTABLE=${PERL_EXECUTABLE} \
 #       -DXMLLINT_EXECUTABLE=${XMLLINT_EXECUTABLE} \
+#       -DJAVA_EXECUTABLE=${JAVA_EXECUTABLE} \
 #       -DENCODING=xxx \
 #       -P "${TOP_SRC_DIR}/development/autotests/export.cmake"
 #
@@ -279,6 +280,16 @@ else()
             endif()
           endif()
         endif()
+	if (NOT _err AND JAVA_EXECUTABLE)
+	  # check with jing
+	  message(STATUS "Calling: ${JAVA_EXECUTABLE} -jar \"${TOP_SRC_DIR}/development/tools/jing.jar\" https://docbook.org/xml/5.0.1/rng/docbook.rng \"${WORKDIR}/${result_file_name}\"")
+	  execute_process(
+	    COMMAND ${JAVA_EXECUTABLE} -jar "${TOP_SRC_DIR}/development/tools/jing.jar" "https://docbook.org/xml/5.2b09/rng/docbook.rng" "${WORKDIR}/${result_file_name}"
+	    OUTPUT_VARIABLE jingout
+	    RESULT_VARIABLE _err)
+	  message(STATUS "_err = ${_err}, jingout = ${jingout}")
+	  Summary(_err "CHecking for empty output of ${JAVA_EXECUTABLE} -jar \"${TOP_SRC_DIR}/development/tools/jing.jar\"")
+	endif()
       endif()
     endif()
   endif()