[Test] Fix bool checks in grid function container test

dune/dorie/test/test-grid-function-container.cc

@@ -153,7 +153,7 @@ bool test_container(GV& gv)
   gf_container.setTime(1.5);
   gf_container.shrink_to_time();
   gf_container.evaluate(entity,x,y);
-  failed |= gf_container.size()==2;
+  failed |= gf_container.size()!=2;
   try {
     gf_container.setTime(0.5);
     gf_container.setTime(1.5);
@@ -164,7 +164,7 @@ bool test_container(GV& gv)
   gf_container.setTime(1.);
   gf_container.shrink_to_time();
   gf_container.evaluate(entity,x,y);
-  failed |= gf_container.size()==1;
+  failed |= gf_container.size()!=1;
   try {
     gf_container.setTime(0.5);
     gf_container.setTime(1.5);
@@ -176,7 +176,7 @@ bool test_container(GV& gv)
     gf_container.pop();
 
   // check that container is void
-  failed |= gf_container.size() == 0;
+  failed |= gf_container.size() != 0;
 
   // evaluate an empty container should rise an error 
   try {