Revert back to explicit json variable

Author: xhochy

cpp/src/arrow/compute/kernels/aggregate_test.cc

@@ -140,13 +140,16 @@ TYPED_TEST(TestNumericSumKernel, SimpleSum) {
   ValidateSum<TypeParam>(&this->ctx_, "[0, 1, 2, 3, 4, 5]",
                          Datum(std::make_shared<ScalarType>(static_cast<T>(5 * 6 / 2))));
 
-  ValidateSum<TypeParam>(&this->ctx_, {"[0, 1, 2, 3, 4, 5]"},
+  std::vector<std::string> json{"[0, 1, 2, 3, 4, 5]"};
+  ValidateSum<TypeParam>(&this->ctx_, json,
                          Datum(std::make_shared<ScalarType>(static_cast<T>(5 * 6 / 2))));
 
-  ValidateSum<TypeParam>(&this->ctx_, {"[0, 1, 2]", "[3, 4, 5]"},
+  json = {"[0, 1, 2]", "[3, 4, 5]"};
+  ValidateSum<TypeParam>(&this->ctx_, json,
                          Datum(std::make_shared<ScalarType>(static_cast<T>(5 * 6 / 2))));
 
-  ValidateSum<TypeParam>(&this->ctx_, {"[0, 1, 2]", "[]", "[3, 4, 5]"},
+  json = {"[0, 1, 2]", "[]", "[3, 4, 5]"};
+  ValidateSum<TypeParam>(&this->ctx_, json,
                          Datum(std::make_shared<ScalarType>(static_cast<T>(5 * 6 / 2))));
 
   const T expected_result = static_cast<T>(14);