fix output status for packing with only fixed molecules.

app/packmol.f90

@@ -678,13 +678,13 @@ program packmol
   if(n.eq.0) then
     call output(n,x, xyzout)
     write(*,dash1_line)
-    write(*,*) ' There are only fixed molecules, therefore there is nothing to do. '
+    write(*,*) ' Success! There are only fixed molecules, therefore there is nothing to pack. '
     write(*,*) ' The output file contains the fixed molecules in the desired positions. '
     write(*,dash1_line)
     write(*,*) ' Wrote output file: ', trim(adjustl(xyzout))
     if ( crd ) write(*,*) ' ... and to CRD file: ', trim(adjustl(crdfile))
     write(*,dash1_line)
-    stop exit_code_input_error
+    stop
   end if
 
   !

testing/input_files/only_one_fixed.inp

@@ -0,0 +1,10 @@
+#
+# A single fixed water molecule
+#
+tolerance 2.0
+filetype pdb
+output output.pdb
+structure ./structure_files/water.pdb
+  number 1
+  fixed 0. 0. 0. 45. 45. 45.
+end structure

testing/test.sh

@@ -18,6 +18,7 @@ julia runtests.jl ./input_files/water_box.inp \
                   ./input_files/bilayer_pbc.inp \
                   ./input_files/solvprotein_pbc.inp \
                   ./input_files/spherical_pbc.inp \
+                  ./input_files/only_one_fixed.inp \
 
 # check if output files are properly generated in a failed run
 ./test_failed.sh ./input_files/water_box_failed.inp packmol.log "FORCED"