feat(backend): add sqlite migrations + app state + tests

backend/tests/sqlite_db_test.cc

@@ -0,0 +1,33 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "csp/db/sqlite_db.h"
+
+#include <sqlite3.h>
+
+namespace {
+
+int CountTable(sqlite3* db, const char* table_name) {
+  sqlite3_stmt* stmt = nullptr;
+  const char* sql =
+      "SELECT COUNT(1) FROM sqlite_master WHERE type='table' AND name=?";
+  REQUIRE(sqlite3_prepare_v2(db, sql, -1, &stmt, nullptr) == SQLITE_OK);
+  REQUIRE(sqlite3_bind_text(stmt, 1, table_name, -1, SQLITE_TRANSIENT) ==
+          SQLITE_OK);
+  REQUIRE(sqlite3_step(stmt) == SQLITE_ROW);
+  const int v = sqlite3_column_int(stmt, 0);
+  sqlite3_finalize(stmt);
+  return v;
+}
+
+}  // namespace
+
+TEST_CASE("migrations create core tables") {
+  auto db = csp::db::SqliteDb::OpenMemory();
+  csp::db::ApplyMigrations(db);
+
+  REQUIRE(CountTable(db.raw(), "users") == 1);
+  REQUIRE(CountTable(db.raw(), "sessions") == 1);
+  REQUIRE(CountTable(db.raw(), "problems") == 1);
+  REQUIRE(CountTable(db.raw(), "submissions") == 1);
+  REQUIRE(CountTable(db.raw(), "wrong_book") == 1);
+}