[ntuple] add vector test for field emulation

tree/ntuple/v7/test/ntuple_emulated.cxx

@@ -3,7 +3,7 @@
 #define NTUPLE_FORK_MACROS
 #include "ntuple_fork.hxx"
 
-TEST(RNTupleEmulated, EmulatedFields)
+TEST(RNTupleEmulated, EmulatedFields_Simple)
 {
    // Write a user-defined class to RNTuple, then "forget" about it and try to load it as an emulated record field.
    // To achieve this "forgetting" we use fork() so that the parent process doesn't know about the class.
@@ -94,3 +94,107 @@ struct Outer {
    reader = RNTupleReader::Open(cmOpts, "ntpl", fileGuard.GetPath());
    reader->LoadEntry(0);
 }
+
+TEST(RNTupleEmulated, EmulatedFields_Vecs)
+{
+   // Write a user-defined class to RNTuple, then "forget" about it and try to load it as an emulated record field.
+   // To achieve this "forgetting" we use fork() so that the parent process doesn't know about the class.
+
+   FileRaii fileGuard("test_ntuple_emulated_fields_vecs.root");
+
+   ExecInFork([&] {
+      // The child process writes the file and exits, but the file must be preserved to be read by the parent.
+      fileGuard.PreserveFile();
+
+      ASSERT_TRUE(gInterpreter->Declare(R"(
+struct Inner {
+   float fFlt; 
+
+   ClassDefNV(Inner, 2);
+};
+
+struct Outer {
+   std::vector<Inner> fInners;
+   Inner fInner;
+   int f;
+
+   ClassDefNV(Outer, 2);
+};
+)"));
+
+      auto model = RNTupleModel::Create();
+      model->AddField(RFieldBase::Create("outers", "std::vector<Outer>").Unwrap());
+
+      auto writer = RNTupleWriter::Recreate(std::move(model), "ntpl", fileGuard.GetPath());
+      writer->Fill();
+
+      void *ptr = writer->GetModel().GetDefaultEntry().GetPtr<void>("outers").get();
+      DeclarePointer("std::vector<Outer>", "ptrOuters", ptr);
+
+      ProcessLine("ptrOuters->push_back(Outer{});");
+      ProcessLine("(*ptrOuters)[0].fInners.push_back(Inner{42.f});");
+      ProcessLine("(*ptrOuters)[0].fInner.fFlt = 84.f;");
+      writer->Fill();
+
+      // TStreamerInfo::Build will report a warning for interpreted classes (but only for members).
+      // See also https://github.com/root-project/root/issues/9371
+      ROOT::TestSupport::CheckDiagsRAII diagRAII;
+      diagRAII.optionalDiag(kWarning, "TStreamerInfo::Build", "has no streamer or dictionary",
+                            /*matchFullMessage=*/false);
+      writer.reset();
+   });
+
+   auto reader = RNTupleReader::Open("ntpl", fileGuard.GetPath());
+   const auto &desc = reader->GetDescriptor();
+
+   {
+      RNTupleDescriptor::RCreateModelOptions opts;
+      opts.fEmulateUnknownTypes = false;
+      try {
+         auto model = desc.CreateModel(opts);
+         FAIL() << "Creating a model without fEmulateUnknownTypes should fail";
+      } catch (ROOT::RException ex) {
+         ASSERT_THAT(ex.GetError().GetReport(), testing::HasSubstr("unknown type"));
+      }
+   }
+
+   {
+      RNTupleDescriptor::RCreateModelOptions opts;
+      opts.fEmulateUnknownTypes = true;
+      auto model = desc.CreateModel(opts);
+      ASSERT_NE(model, nullptr);
+
+      const auto &outers = model->GetConstField("outers");
+      ASSERT_EQ(outers.GetTypeName(), "std::vector<Outer>");
+      ASSERT_EQ(outers.GetStructure(), ENTupleStructure::kCollection);
+      ASSERT_EQ(outers.GetSubFields().size(), 1);
+
+      const auto subfields = outers.GetSubFields();
+      const auto *outer = subfields[0];
+      ASSERT_EQ(outer->GetTypeName(), "Outer");
+      ASSERT_EQ(outer->GetStructure(), ENTupleStructure::kRecord);
+
+      const auto outersubfields = outer->GetSubFields();
+      ASSERT_EQ(outersubfields.size(), 3);
+
+      const auto *inners = outersubfields[0];
+      ASSERT_EQ(inners->GetTypeName(), "std::vector<Inner>");
+      ASSERT_EQ(inners->GetFieldName(), "fInners");
+      ASSERT_EQ(inners->GetStructure(), ENTupleStructure::kCollection);
+      ASSERT_EQ(inners->GetSubFields().size(), 1);
+      ASSERT_EQ(inners->GetSubFields()[0]->GetFieldName(), "_0");
+
+      const auto innersubfields = inners->GetSubFields();
+      const auto *inner = innersubfields[0];
+      ASSERT_EQ(inner->GetTypeName(), "Inner");
+      ASSERT_EQ(inner->GetStructure(), ENTupleStructure::kRecord);
+      ASSERT_EQ(inner->GetSubFields().size(), 1);
+      ASSERT_EQ(inner->GetSubFields()[0]->GetFieldName(), "fFlt");
+   }
+
+   // Now test loading entries with a reader
+   RNTupleDescriptor::RCreateModelOptions cmOpts;
+   cmOpts.fEmulateUnknownTypes = true;
+   reader = RNTupleReader::Open(cmOpts, "ntpl", fileGuard.GetPath());
+   reader->LoadEntry(0);
+}