List<HikariDataSource> build(Environment environment, Callback<HikariDataSource> callback) {
        List<HikariDataSource> dataSources = new ArrayList<>();
        Binder.get(environment).bind("db", Bindable.ofInstance(this));
        Preconditions.checkArgument(Objects.nonNull(num), "db.num is null");
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(user), "db.user or db.user.[index] is null");
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(password), "db.password or db.password.[index] is null");
        for (int index = 0; index < num; index++) {
            int currentSize = index + 1;
            Preconditions.checkArgument(url.size() >= currentSize, "db.url.%s is null", index);
            DataSourcePoolProperties poolProperties = DataSourcePoolProperties.build(environment);
            if (StringUtils.isEmpty(poolProperties.getDataSource().getDriverClassName())) {
                poolProperties.setDriverClassName(JDBC_DRIVER_NAME);
            }
            poolProperties.setJdbcUrl(url.get(index).trim());
            poolProperties.setUsername(getOrDefault(user, index, user.get(0)).trim());
            poolProperties.setPassword(getOrDefault(password, index, password.get(0)).trim());
            HikariDataSource ds = poolProperties.getDataSource();
            if (StringUtils.isEmpty(ds.getConnectionTestQuery())) {
                ds.setConnectionTestQuery(TEST_QUERY);
            }
            
            dataSources.add(ds);
            callback.accept(ds);
        }
        Preconditions.checkArgument(CollectionUtils.isNotEmpty(dataSources), "no datasource available");
        return dataSources;
    }
@Test
    void externalDatasourceFailureWithLarkInfo() {
        assertThrows(IllegalArgumentException.class, () -> {
            
            MockEnvironment environment = new MockEnvironment();
            new ExternalDataSourceProperties().build(environment, null);
            
        });
        
    }