Development
Catch C/C++ Tests
While we prefer the sqllogic tests for testing most functionality, for certain tests only SQL is not sufficient. This typically happens when you want to test the C++ API. When using pure SQL is really not an option it might be necessary to make a C++ test using Catch.  
Catch tests reside in the test directory as well. Here is an example of a catch test that tests the storage of the system:  
```cpp
#include "catch.hpp"
#include "test_helpers.hpp"

TEST_CASE("Test simple storage", "[storage]") {
auto config = GetTestConfig();
unique_ptr<QueryResult> result;
auto storage_database = TestCreatePath("storage_test");

// make sure the database does not exist
DeleteDatabase(storage_database);
{
// create a database and insert values
DuckDB db(storage_database, config.get());
Connection con(db);
REQUIRE_NO_FAIL(con.Query("CREATE TABLE test (a INTEGER, b INTEGER);"));
REQUIRE_NO_FAIL(con.Query("INSERT INTO test VALUES (11, 22), (13, 22), (12, 21), (NULL, NULL)"));
REQUIRE_NO_FAIL(con.Query("CREATE TABLE test2 (a INTEGER);"));
REQUIRE_NO_FAIL(con.Query("INSERT INTO test2 VALUES (13), (12), (11)"));
}
// reload the database from disk a few times
for (idx_t i = 0; i < 2; i++) {
DuckDB db(storage_database, config.get());
Connection con(db);
result = con.Query("SELECT * FROM test ORDER BY a");
REQUIRE(CHECK_COLUMN(result, 0, {Value(), 11, 12, 13}));
REQUIRE(CHECK_COLUMN(result, 1, {Value(), 22, 21, 22}));
result = con.Query("SELECT * FROM test2 ORDER BY a");
REQUIRE(CHECK_COLUMN(result, 0, {11, 12, 13}));
}
DeleteDatabase(storage_database);
}
```  
The test uses the `TEST_CASE` wrapper to create each test. The database is created and queried using the C++ API. Results are checked using either `REQUIRE_FAIL`/`REQUIRE_NO_FAIL` (corresponding to statement ok and statement error) or `REQUIRE(CHECK_COLUMN(...))` (corresponding to query with a result check). Every test that is created in this way needs to be added to the corresponding `CMakeLists.txt`.