diff --git a/test/unit/error.test.ts b/test/unit/error.test.ts
new file mode 100644
index 0000000..5e8d39e
--- /dev/null
+++ b/test/unit/error.test.ts
@@ -0,0 +1,31 @@
+import { describe, expect, test } from 'vitest';
+
+import { FreezerError, raise } from '../../src/error';
+
+describe('Test FreezerError class', () => {
+  test('without error code', () => {
+    const error = new FreezerError('Some error');
+
+    expect(error).toBeInstanceOf(Error);
+    expect(error).toBeInstanceOf(FreezerError);
+
+    expect(error.message).toMatchInlineSnapshot(`"Some error"`);
+    expect(error.code).toBeUndefined();
+  });
+
+  test('with error code', () => {
+    const error = new FreezerError('Some error', 42);
+
+    expect(error).toBeInstanceOf(Error);
+    expect(error).toBeInstanceOf(FreezerError);
+
+    expect(error.message).toMatchInlineSnapshot(`"Some error"`);
+    expect(error.code).toMatchInlineSnapshot(`42`);
+  });
+
+  test('raise error', () => {
+    expect(() => raise('Some error')).toThrowErrorMatchingInlineSnapshot(
+      `[Error: Some error]`
+    );
+  });
+});