自动生成的dbt Python测试疑似硬编码导致恒失败问题咨询

项目概况 #

我有一个Python DBT项目，通过YAML定义的数据模型如下：

version: 2
models:
- name: company
  description: ''
  columns:
  - name: ID
    description: Unique identifier for the company entity. It is the company name
    tests:
      - unique
      - not_null
      - dbt_expectations.expect_column_values_to_be_of_type:
          column_type: VARCHAR
  - name: REMOTE_ID
    description: Company name
    tests:
      - dbt_expectations.expect_column_values_to_be_of_type:
          column_type: VARCHAR
  - name: CREATED_AT
    description: ''
    tests:
      - dbt_expectations.expect_column_values_to_be_of_type:
          column_type: TIMESTAMP_TZ
      - not_null
  - name: UPDATED_AT
    description: ''
    tests:
      - dbt_expectations.expect_column_values_to_be_of_type:
          column_type: TIMESTAMP_TZ

执行流程与测试失败信息 #

执行dbt compile、dbt run后运行dbt test，出现测试失败，控制台输出：

17:59:30  Failure in test dbt_expectations_expect_column_values_to_be_of_type_company_CREATED_AT__TIMESTAMP_TZ (models/fizzbuzz/domain/company.yml)
17:59:30    Got 1 result, configured to fail if != 0
17:59:30  
17:59:30    compiled Code at target/compiled/myapp/models/fizzbuzz/domain/company.yml/dbt_expectations_expect_column_837854ce21e79ee1abe42f69891c68e9.sql

编译后的测试SQL内容 #

查看编译后的SQL文件，内容如下：

WITH relation_columns
     AS (SELECT Cast('ID' AS VARCHAR)      AS relation_column,
                Cast('VARCHAR' AS VARCHAR) AS relation_column_type
         UNION ALL
         SELECT Cast('REMOTE_ID' AS VARCHAR) AS relation_column,
                Cast('VARCHAR' AS VARCHAR)   AS relation_column_type
         UNION ALL
         SELECT Cast('CREATED_AT' AS VARCHAR)    AS relation_column,
                Cast('TIMESTAMP_NTZ' AS VARCHAR) AS relation_column_type
         UNION ALL
         SELECT Cast('UPDATED_AT' AS VARCHAR)    AS relation_column,
                Cast('TIMESTAMP_NTZ' AS VARCHAR) AS relation_column_type),
     test_data
     AS (SELECT *
         FROM   relation_columns
         WHERE  relation_column = 'CREATED_AT'
                AND relation_column_type NOT IN ( 'TIMESTAMP_TZ' ))
SELECT *
FROM   test_data 

疑问 #

我理解dbt compile会根据YAML定义生成上述测试SQL，dbt test执行该SQL判断测试是否通过。但该测试逻辑未关联实际的company数据库表，而是使用硬编码的CTE，其中CREATED_AT的类型被设为TIMESTAMP_NTZ，测试条件为类型不等于TIMESTAMP_TZ时返回结果，这会导致测试必然失败。请问这是DBT的bug，还是我对DBT测试机制存在误解？

内容的提问来源于stack exchange，提问作者hotmeatballsoup