alexzorin / dbt-unit-test-poc

dbt-unit-test-poc

This project exists to demonstrate an issue with https://github.com/EqualExperts/dbt-unit-testing.

When using a macro to access the model object, it is replaced with the tests model. This only happens when running tests via dbt-unit-testing, not via dbt run etc.

This means if the macro relies on accessing model.columns, for example, it is not possible e.g.:

{%- set columns = (
    model.columns.values()
    | list
) -%}

This will just produce an empty list, because tests has no values.

Running

This is essentially the dbt init project, with a macro added to access column data, and a basic unit test using dbt-unit-testing.

Make sure you have docker-compose installed and just run:

docker compose up --attach dbt

You will see that the test crashes.

Of course, you can just try run the dbt project locally.

There is a workaround branch that uses this to access the columns instead of model.columns, but this is undesirable:

diff --git a/macros/demo.sql b/macros/demo.sql
index f55d77c..e03f79c 100644
--- a/macros/demo.sql
+++ b/macros/demo.sql
@@ -9,7 +9,7 @@
 {%- macro demo_cols() -%}
     {%- if execute -%}
         {%- set columns = (
-            model.columns.values()
+            graph.nodes["model.demo.my_second_dbt_model"].columns.values()
             | list
         ) -%}
         {%- for col in columns -%}

Running the workaround

git checkout workaround
docker compose up --attach dbt

Relevant Files

• Macro line that is the source of the crash:

  dbt-unit-test-poc/macros/demo.sql

  Lines 11 to 13 in d66958a

  	{%- set columns = (
  	model.columns.values()
  	| list

• Model that uses the macro: https://github.com/alexzorin/dbt-unit-test-poc/blob/main/models/example/my_second_dbt_model.sql#L2
• The unit test: https://github.com/alexzorin/dbt-unit-test-poc/blob/main/tests/unit/demo.sql