should be it

external/duckdb/test/sql/storage/test_checksum.cpp

@@ -0,0 +1,37 @@
+#include "catch.hpp"
+#include "duckdb/common/file_system.hpp"
+#include "test_helpers.hpp"
+
+using namespace duckdb;
+using namespace std;
+
+TEST_CASE("Test functioning of checksum", "[storage]") {
+	duckdb::unique_ptr<FileSystem> fs = FileSystem::CreateLocal();
+	duckdb::unique_ptr<DuckDB> database;
+	auto storage_database = TestCreatePath("checksum_test");
+	auto config = GetTestConfig();
+
+	// 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);"));
+		REQUIRE_NO_FAIL(con.Query("INSERT INTO test VALUES (3);"));
+	}
+	// we can open the database file now
+	REQUIRE_NOTHROW(database = make_uniq<DuckDB>(storage_database, config.get()));
+	database.reset();
+
+	// now write random values into the file
+	auto handle = fs->OpenFile(storage_database, FileFlags::FILE_FLAGS_WRITE);
+	int8_t value = 0x22;
+	fs->Write(*handle, &value, sizeof(int8_t), 100);
+	handle->Sync();
+	handle.reset();
+	// reloading the database no longer works
+	REQUIRE_THROWS(database = make_uniq<DuckDB>(storage_database, config.get()));
+
+	DeleteDatabase(storage_database);
+}