2 files changed, 60 insertions, 0 deletions
diff --git a/packages/taler-util/src/index.ts b/packages/taler-util/src/index.ts
index ec5b85d29..d9ab60910 100644
--- a/packages/taler-util/src/index.ts
+++ b/packages/taler-util/src/index.ts
@@ -29,6 +29,7 @@ export * from "./http-client/types.js";
 export * from "./http-status-codes.js";
 export * from "./i18n.js";
 export * from "./iban.js";
+export * from "./invariants.js";
 export * from "./kdf.js";
 export * from "./libeufin-api-types.js";
 export * from "./libtool-version.js";
diff --git a/packages/taler-util/src/invariants.ts b/packages/taler-util/src/invariants.ts
new file mode 100644
index 000000000..c6e9b8113
--- /dev/null
+++ b/packages/taler-util/src/invariants.ts
@@ -0,0 +1,59 @@
+/*
+ This file is part of GNU Taler
+ (C) 2019-2024 Taler Systems S.A.
+
+ GNU Taler is free software; you can redistribute it and/or modify it under the
+ terms of the GNU General Public License as published by the Free Software
+ Foundation; either version 3, or (at your option) any later version.
+
+ GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
+ WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+ A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along with
+ GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+/**
+ * Helpers for invariants.
+ */
+
+/**
+ * An invariant has been violated.
+ */
+export class InvariantViolatedError extends Error {
+  constructor(message?: string) {
+    super(message);
+    Object.setPrototypeOf(this, InvariantViolatedError.prototype);
+  }
+}
+
+/**
+ * Check a database invariant.
+ *
+ * A violation of this invariant means that the database is inconsistent.
+ */
+export function checkDbInvariant(b: boolean, m?: string): asserts b {
+  if (!b) {
+    if (m) {
+      throw Error(`BUG: database invariant failed (${m})`);
+    } else {
+      throw Error("BUG: database invariant failed");
+    }
+  }
+}
+
+/**
+ * Check a logic invariant.
+ *
+ * A violation of this invariant means that there is a logic bug in the program.
+ */
+export function checkLogicInvariant(b: boolean, m?: string): asserts b {
+  if (!b) {
+    if (m) {
+      throw Error(`BUG: logic invariant failed (${m})`);
+    } else {
+      throw Error("BUG: logic invariant failed");
+    }
+  }
+}