diff --git a/src/utils/index.test.ts b/src/utils/index.test.ts
index 57a41101..203ceede 100644
--- a/src/utils/index.test.ts
+++ b/src/utils/index.test.ts
@@ -1,7 +1,15 @@
 // SPDX-License-Identifier: MIT
 // Copyright (c) 2020 The Pybricks Authors
 
-import { hex } from '.';
+import { assert, hex } from '.';
+
+test('assert', () => {
+    const assertTrue = jest.fn(() => assert(true, 'should not throw'));
+    assertTrue();
+    expect(assertTrue).toHaveReturned();
+
+    expect(() => assert(false, 'should throw')).toThrow();
+});
 
 test('hex', () => {
     expect(hex(0, 2)).toBe('0x00');
diff --git a/src/utils/index.ts b/src/utils/index.ts
index 7c336e75..ea7af95f 100644
--- a/src/utils/index.ts
+++ b/src/utils/index.ts
@@ -8,7 +8,6 @@
  * @param message Informational message for debugging
  */
 export function assert(condition: boolean, message: string): void {
-    /* istanbul ignore next */
     if (!condition) {
         throw Error(message);
     }