WIP: add unit test for formatErrorMessage function

Signed-off-by: Sumu <[email protected]>

packages/aws-cdk/test/api/util/error.test.ts

@@ -0,0 +1,26 @@
+import { formatErrorMessage } from '../../../lib/util/error';
+
+describe('formatErrorMessage', () => {
+  test('should return the formatted message for a regular Error object', () => {
+    const error = new Error('Something went wrong');
+    const result = formatErrorMessage(error);
+    expect(result).toBe('Something went wrong');
+  });
+
+  test('should return the formatted message for an AggregateError', () => {
+    const error = {
+      errors: [
+        new Error('Inner error 1'),
+        new Error('Inner error 2'),
+        new Error('Inner error 3'),
+      ],
+    };
+    const result = formatErrorMessage(error);
+    expect(result).toBe('AggregateError: Inner error 1\nInner error 2\nInner error 3');
+  });
+
+  test('should return "Unknown error" for null or undefined error', () => {
+    expect(formatErrorMessage(null)).toBe('Unknown error');
+    expect(formatErrorMessage(undefined)).toBe('Unknown error');
+  });
+});