Init MPIHelper even for tests that are purely sequential

test/cosseratenergytest.cc

@@ -336,6 +336,8 @@ void testEnergyGradient(Basis basis)
 
 int main(int argc, char** argv)
 {
+    MPIHelper::instance(argc, argv);
+
     const int domainDim = 2;
 
     // ////////////////////////////////////////////////////////

test/harmonicenergytest.cc

@@ -111,5 +111,7 @@ void testUnitVector3d()
 
 int main(int argc, char** argv)
 {
+    MPIHelper::instance(argc, argv);
+
     testUnitVector3d<2>();
 }