fix: modern diag manager time_bnds issue when running for 1 day and r…

…unning daily data (NOAA-GFDL#1523)

diag_manager/fms_diag_file_object.F90

@@ -1473,10 +1473,8 @@ subroutine write_time_data(this)
   diag_file => this%FMS_diag_file
   fms2io_fileobj => diag_file%fms2io_fileobj
 
-  !< If data has not been written for the current unlimited dimension
-  !! ignore this. The diag_file%unlim_dimension_level .ne. 1 is there to ensure
-  !! that at least one time level is written (this is needed for the combiner)
-  if (.not. diag_file%data_has_been_written .and. diag_file%unlim_dimension_level .ne. 1) return
+  !< If data has not been written for the current unlimited dimension leave the subroutine
+  if (.not. diag_file%data_has_been_written) return
 
   if (diag_file%get_time_ops()) then
     middle_time = (diag_file%last_output+diag_file%next_output)/2

test_fms/diag_manager/check_var_masks.F90

@@ -34,6 +34,7 @@ program check_var_masks
   real                               :: ans_var_mask
   real                               :: ans_var
   integer                            :: i, j
+  real                               :: time_data(2)
 
   call fms_init()
 
@@ -49,6 +50,14 @@ program check_var_masks
   call get_dimension_size(fileobj, "y", ny)
   if (ny .ne. 180) call mpp_error(FATAL, "y is not the correct size!")
 
+  call read_data(fileobj, "time", time_data(1))
+  if (time_data(1) .ne. real(12.))&
+    call mpp_error(FATAL, "The time data is not the expected result")
+
+  call read_data(fileobj, "time_bnds", time_data)
+  if (time_data(1) .ne. real(0.) .or. time_data(2) .ne. real(24.)) &
+    call mpp_error(FATAL, "The time bnds data is not the expected result")
+
   allocate(vardata(nx,ny))
 
   ans_var_mask = 0.