Function ValidateNumProjectNodes

cpp/src/arrow/engine/substrait/serde_test.cc:222–233

Validate the number of expected ProjectNodes Project nodes are sometimes added by emit elements and we may want to verify that we are not adding too many

/// Project nodes are sometimes added by emit elements and we may want to
/// verify that we are not adding too many
void ValidateNumProjectNodes(int expected_projections, const std::shared_ptr<Buffer>& buf,
                             const ConversionOptions& conversion_options) {
  std::shared_ptr<ExtensionIdRegistry> sp_ext_id_reg = MakeExtensionIdRegistry();
  ExtensionIdRegistry* ext_id_reg = sp_ext_id_reg.get();
  ExtensionSet ext_set(ext_id_reg);
  ASSERT_OK_AND_ASSIGN(auto sink_decls, DeserializePlans(
                                            *buf, [] { return kNullConsumer; },
                                            ext_id_reg, &ext_set, conversion_options));
  auto& other_declrs = std::get<acero::Declaration>(sink_decls[0].inputs[0]);
  int num_projections = CountProjectNodeOptionsInDeclarations(other_declrs);
  ASSERT_EQ(num_projections, expected_projections);
}

TEST(Substrait, SupportedTypes) {
  auto ExpectEq = [](std::string_view json, std::shared_ptr<DataType> expected_type) {