LdapManager ldapManager = new LdapManager();
        ldapManager.init();

        // Null input should return empty string
        assertEquals("", ldapManager.escapeLDAPSearchFilter(null));
    }

    @Test
    public void test_escapeLDAPSearchFilter_withEmptyString() {
        LdapManager ldapManager = new LdapManager();
        ldapManager.init();

        user.setRoles(new String[] { "role1", "role2" });
        user.setGroups(new String[] { "group1", "group2" });
        return user;
    }

    // Test LdapManager implementation
    private static class TestLdapManager extends LdapManager {
        boolean insertCalled = false;
        boolean deleteCalled = false;
        boolean changePasswordCalled = false;
        boolean applyCalled = false;