// getMessage() may return null when constructed with null
        // This is expected behavior for exceptions with null cause
    }

    @Test
    public void test_nestedCause() {
        // Test with nested exceptions
        RuntimeException rootCause = new RuntimeException("Root cause");
        ParseException parseException = new ParseException("Parse error");

        } catch (final RuntimeException e) {
            caught = true;
            assertEquals("Test exception", e.getMessage());
        }
        assertTrue(caught);
    }

    @Test
    public void test_nestedCause() {
        final IllegalArgumentException rootCause = new IllegalArgumentException("Invalid argument");
        final RuntimeException middleCause = new RuntimeException("Middle error", rootCause);