Added `none` as an option for fields_to_plot (#2419)

* Added `none` as an option for fields_to_plot

* Added CI test case

* Further updates, for picmi and CI tests

* Skip the call to amrex::WriteMultiLevelPlotfile when writing no fields

* Now clears m_varnames_fields

* Don't allocate m_mf_output if no varnames

* Updated WarpX-tests.ini

1 files changed, 11 insertions, 9 deletions

diff --git a/Source/Diagnostics/FlushFormats/FlushFormatPlotfile.cpp b/Source/Diagnostics/FlushFormats/FlushFormatPlotfile.cpp
index 4655128d5..513d97f3a 100644
--- a/Source/Diagnostics/FlushFormats/FlushFormatPlotfile.cpp
+++ b/Source/Diagnostics/FlushFormats/FlushFormatPlotfile.cpp
@@ -71,15 +71,17 @@ FlushFormatPlotfile::WriteToFile (
     VisMF::Header::Version current_version = VisMF::GetHeaderVersion();
     VisMF::SetHeaderVersion(amrex::VisMF::Header::Version_v1);
     if (plot_raw_fields) rfs.emplace_back("raw_fields");
-    amrex::WriteMultiLevelPlotfile(filename, nlev,
-                                   amrex::GetVecOfConstPtrs(mf),
-                                   varnames, geom,
-                                   static_cast<Real>(time), iteration, warpx.refRatio(),
-                                   "HyperCLaw-V1.1",
-                                   "Level_",
-                                   "Cell",
-                                   rfs
-                                   );
+    if (varnames.size() > 0) {
+        amrex::WriteMultiLevelPlotfile(filename, nlev,
+                                       amrex::GetVecOfConstPtrs(mf),
+                                       varnames, geom,
+                                       static_cast<Real>(time), iteration, warpx.refRatio(),
+                                       "HyperCLaw-V1.1",
+                                       "Level_",
+                                       "Cell",
+                                       rfs
+                                       );
+    }
 
     WriteAllRawFields(plot_raw_fields, nlev, filename, plot_raw_fields_guards);