message: Add some extra STRING_AGG tests
diff: @@ -84,15 +84,17 @@ TEST_CASE("Test scalar aggregates with many different types", "[aggregate]") {
  // string agg
  result = con.Query(
  - "SELECT STRING_AGG('hello', ' '), STRING_AGG('hello', NULL), STRING_AGG(NULL, ' '), STRING_AGG(NULL, NULL)");
  + "SELECT STRING_AGG('hello', ' '), STRING_AGG('hello', NULL), STRING_AGG(NULL, ' '), STRING_AGG(NULL, NULL), STRING_AGG('', '')");
  REQUIRE(CHECK_COLUMN(result, 0, {"hello"}));
  REQUIRE(CHECK_COLUMN(result, 1, {Value()}));
  REQUIRE(CHECK_COLUMN(result, 2, {Value()}));
  REQUIRE(CHECK_COLUMN(result, 3, {Value()}));
  + REQUIRE(CHECK_COLUMN(result, 4, {""}));
  REQUIRE_FAIL(con.Query("SELECT STRING_AGG()"));
  REQUIRE_FAIL(con.Query("SELECT STRING_AGG('hello')"));
  REQUIRE_FAIL(con.Query("SELECT STRING_AGG(1, 2, 3)"));
  +
  }
  TEST_CASE("Test aggregates with many different types", "[aggregate]") {
  @@ -117,8 +119,12 @@ TEST_CASE("Test aggregates with many different types", "[aggregate]") {
  REQUIRE(CHECK_COLUMN(result, 2, {Value()}));
  REQUIRE(CHECK_COLUMN(result, 3, {Value()}));
  // add string_agg
  - result = con.Query("SELECT STRING_AGG(s, ' ') FROM strings");
  + result = con.Query("SELECT STRING_AGG(s, ' '), STRING_AGG(s, ''), STRING_AGG('', ''), STRING_AGG('hello', ' ') FROM strings");
  REQUIRE(CHECK_COLUMN(result, 0, {"hello world r"}));
  + REQUIRE(CHECK_COLUMN(result, 1, {"helloworldr"}));
  + REQUIRE(CHECK_COLUMN(result, 2, {""}));
  + REQUIRE(CHECK_COLUMN(result, 3, {"hello hello hello hello"}));
  +
  // more complex agg (groups)
  result = con.Query(
  "SELECT g, COUNT(*), COUNT(s), MIN(s), MAX(s), STRING_AGG(s, ' ') FROM strings GROUP BY g ORDER BY g");
  