Add broadcast unit tests

tests/mpi_test_Messenger.cpp

@@ -93,7 +93,7 @@ TEST_CASE("Messenger", "[mpi]") {
     REQUIRE(size == commSize());
   }
 
-  SECTION("allToAll") {
+  SECTION("all to all") {
     // chars
     mpi_check::test_allToAll<char>();
     mpi_check::test_allToAll<wchar_t>();
@@ -124,4 +124,62 @@ TEST_CASE("Messenger", "[mpi]") {
     // compound trivial type
     mpi_check::test_allToAll<mpi_check::tri_int>();
   }
+
+  SECTION("broadcast value") {
+    {
+      // simple type
+      int value{(3+commRank())*2};
+      broadcast(value, 0);
+      REQUIRE(value == 6);
+    }
+
+    {
+      // trivial simple type
+      mpi_check::integer value{(3+commRank())*2};
+      broadcast(value, 0);
+      REQUIRE((value == 6));
+    }
+
+    {
+      // compound trivial type
+      mpi_check::tri_int value{(3+commRank())*2, 2+commRank(), 4-commRank()};
+      broadcast(value, 0);
+      REQUIRE((value == mpi_check::tri_int{6,2,4}));
+    }
+  }
+
+  SECTION("broadcast array") {
+    {
+      // simple type
+      Array<int> array(3);
+      array[0] = (3+commRank())*2;
+      array[1] = 2+commRank();
+      array[2] = 4-commRank();
+      broadcast(array, 0);
+      REQUIRE(((array[0]==6)  and (array[1]==2) and (array[2]==4)));
+    }
+
+    {
+      // trivial simple type
+      Array<mpi_check::integer> array(3);
+      array[0] = (3+commRank())*2;
+      array[1] = 2+commRank();
+      array[2] = 4-commRank();
+      broadcast(array, 0);
+      REQUIRE(((array[0]==6)  and (array[1]==2) and (array[2]==4)));
+    }
+
+    {
+      // compound trivial type
+      Array<mpi_check::tri_int> array(3);
+      array[0] = mpi_check::tri_int{(3+commRank())*2, 2+commRank(), 4-commRank()};
+      array[1] = mpi_check::tri_int{(2+commRank())*4, 3+commRank(), 1-commRank()};
+      array[2] = mpi_check::tri_int{(5+commRank()), -3+commRank(), commRank()};
+      broadcast(array, 0);
+      REQUIRE(((array[0] == mpi_check::tri_int{6, 2,4}) and
+               (array[1] == mpi_check::tri_int{8, 3,1}) and
+               (array[2] == mpi_check::tri_int{5,-3,0})));
+    }
+  }
+
 }