Ensure QueryAssertions::materialize() supports lazies (facebookincuba…

…tor#10667)

Summary:
Pull Request resolved: facebookincubator#10667

Ensure the QueryAssertions::materialize() utility correctly handles
lazy vectors. Previsouly it would blindly try to upcast it to a simple vector,
which would fail by returning a null pointer and crashing inside variantAt().

Reviewed By: mbasmanova

Differential Revision: D60779568

velox/exec/tests/utils/QueryAssertions.cpp

@@ -879,14 +879,20 @@ std::vector<MaterializedRow> materialize(const RowVectorPtr& vector) {
  std::vector<MaterializedRow> rows;
  rows.reserve(size);
 
- auto& rowType = vector->type()->as<TypeKind::ROW>();
+ auto numColumns = vector->childrenSize();
+ std::vector<VectorPtr> simpleVectors(numColumns);
+
+ // variantAt() assumes you can upcast to SimpleVector, so we need to take
+ // the inner vector out of lazies first.
+ for (size_t i = 0; i < numColumns; ++i) {
+ simpleVectors[i] = BaseVector::loadedVectorShared(vector->childAt(i));
+ }
 
  for (size_t i = 0; i < size; ++i) {
- auto numColumns = rowType.size();
  MaterializedRow row;
  row.reserve(numColumns);
  for (size_t j = 0; j < numColumns; ++j) {
- row.push_back(variantAt(vector->childAt(j), i));
+ row.push_back(variantAt(simpleVectors[j], i));
  }
  rows.push_back(row);
  }