Adding descriptions to tests no longer possible with 0.20.0

[mirosval]

Describe the bug

In 0.19 the following would work (in a Model or Source):

     columns:
      - name: user_cohort
        tests:
          - not_null:
              severity: warn
              description: "severity reduced pending further investigation"

In 0.20 I get:

Runtime Error
  Compilation Error in test not_null_<test_name> (<model_yaml>)
    macro 'dbt_macro__test_not_null' takes no keyword argument 'description'

    > in macro test_not_null (macros/schema_tests/not_null.sql)

Steps To Reproduce

Add description: aaa under a test in a model or source.

Expected behavior

No compilation error

System information

Which database are you using dbt with?

• postgres
• redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

installed version: 0.20.0
   latest version: 0.20.0

Up to date!

Plugins:
  - bigquery: 0.20.0
  - snowflake: 0.20.0
  - redshift: 0.20.0
  - postgres: 0.20.0

The operating system you're using: macOS 11.4

The output of python --version: 3.9.5

Additional context

I have not found a mention of this in the release notes and to be fair the updated docs don't say this should be possible. But it did work before and I think its useful especially when you want to document why you downgraded a test to a warning instead of an error.

[jtcohen6]

Thanks for opening @mirosval. As you note, this wasn't officially supported documented in previous versions of dbt. At the same time, it did sort-of work, and I totally get why it's desirable.

The description test argument (as in your code snippet above) couldn't reference doc blocks, and it wouldn't show up in the node-level description property in manifest.json; it would just be nested under test_metadata. We do want to support descriptions on tests, ultimately, in a way that's more consistent with descriptions on all other resource types: #2578, #3249.

In the meantime, I think a more general approach that could get you what you're after would be meta properties on tests: #3629.

I'm going to close this issue in favor of the meta approach in the shorter term, and real description support in the longer term.