diff --git a/src/RelayError.test.ts b/src/RelayError.test.ts
new file mode 100644
index 00000000..742b799f
--- /dev/null
+++ b/src/RelayError.test.ts
@@ -0,0 +1,23 @@
+import { assertThrows } from '@std/assert';
+
+import { RelayError } from '@/RelayError.ts';
+
+Deno.test('Construct a RelayError from the reason message', () => {
+  assertThrows(
+    () => {
+      throw RelayError.fromReason('duplicate: already exists');
+    },
+    RelayError,
+    'duplicate: already exists',
+  );
+});
+
+Deno.test('Throw a new RelayError if the OK message is false', () => {
+  assertThrows(
+    () => {
+      RelayError.assert(['OK', 'yolo', false, 'error: bla bla bla']);
+    },
+    RelayError,
+    'error: bla bla bla',
+  );
+});