Add tests to sources, snapshots and seeds when using TestBehavior.AFT…

…ER_EACH (#599)

Previously Cosmos would only create a task group when using
`TestBehavior.AFTER_EACH` for nodes of the type `DbtResourceType.MODEL`.
This change adds the same behavior to snapshots and seeds.

For this to work as expected with sources, we would need to create a
default operator to handle `DbtResourceType.SOURCE`, which is outside
the scope of the current ticket. Once this operator exists, sources will
also lead to creating a task group.

All the test selectors were tested successfully with dbt 1.6.

This screenshot illustrates the validation of this feature, with an
adapted version of Jaffle Shop:
<img width="1502" alt="Screenshot 2023-10-13 at 19 43 52"
src="https://github.com/astronomer/astronomer-cosmos/assets/272048/893ac557-1846-4ed1-b5e2-913a7bd38485">

The modifications that were done to jaffle_shop were:

Appended the following lines to
`dev/dags/dbt/jaffle_shop/models/schema.yml`:
```
seeds:
  - name: raw_customers
    description: Raw data from customers
    columns:
      - name: id
        tests:
          - unique
          - not_null

snapshots:
  - name: orders_snapshot
    description: Snapshot of orders
    columns:
      - name: orders_snapshot.order_id
        tests:
          - unique
          - not_null
```

And created the file
`dev/dags/dbt/jaffle_shop/snapshots/orders_snapshot.sql` with:
```
{% snapshot orders_snapshot %}

{{
    config(
      target_database='postgres',
      target_schema='public',
      unique_key='order_id',

      strategy='timestamp',
      updated_at='order_date',
    )
}}

select * from {{ ref('jaffle_shop', 'orders') }}

{% endsnapshot %}
```

Closes: #474

cosmos/airflow/graph.py

@@ -56,7 +56,7 @@ def create_test_task_metadata(
     execution_mode: ExecutionMode,
     task_args: dict[str, Any],
     on_warning_callback: Callable[..., Any] | None = None,
-    model_name: str | None = None,
+    node: DbtNode | None = None,
 ) -> TaskMetadata:
     """
     Create the metadata that will be used to instantiate the Airflow Task that will be used to run the Dbt test node.
@@ -66,13 +66,18 @@ def create_test_task_metadata(
     :param task_args: Arguments to be used to instantiate an Airflow Task
     :param on_warning_callback: A callback function called on warnings with additional Context variables “test_names”
     and “test_results” of type List.
-    :param model_name: If the test relates to a specific model, the name of the model it relates to
+    :param node: If the test relates to a specific node, the node reference
     :returns: The metadata necessary to instantiate the source dbt node as an Airflow task.
     """
     task_args = dict(task_args)
     task_args["on_warning_callback"] = on_warning_callback
-    if model_name is not None:
-        task_args["models"] = model_name
+    if node is not None:
+        if node.resource_type == DbtResourceType.MODEL:
+            task_args["models"] = node.name
+        elif node.resource_type == DbtResourceType.SOURCE:
+            task_args["select"] = f"source:{node.unique_id[len('source.'):]}"
+        else:  # tested with node.resource_type == DbtResourceType.SEED or DbtResourceType.SNAPSHOT
+            task_args["select"] = node.name
     return TaskMetadata(
         id=test_task_name,
         operator_class=calculate_operator_class(
@@ -112,6 +117,8 @@ def create_task_metadata(
                 task_id = "run"
         else:
             task_id = f"{node.name}_{node.resource_type.value}"
+            if use_task_group is True:
+                task_id = node.resource_type.value
 
         task_metadata = TaskMetadata(
             id=task_id,
@@ -163,7 +170,7 @@ def generate_task_or_group(
                     "test",
                     execution_mode,
                     task_args=task_args,
-                    model_name=node.name,
+                    node=node,
                     on_warning_callback=on_warning_callback,
                 )
                 test_task = create_airflow_task(test_meta, dag, task_group=model_task_group)

cosmos/constants.py

@@ -70,7 +70,7 @@ def _missing_value_(cls, value):  # type: ignore
 
 DEFAULT_DBT_RESOURCES = DbtResourceType.__members__.values()
 
-
-TESTABLE_DBT_RESOURCES = {
-    DbtResourceType.MODEL
-}  # TODO: extend with DbtResourceType.SOURCE, DbtResourceType.SNAPSHOT, DbtResourceType.SEED)
+# dbt test runs tests defined on models, sources, snapshots, and seeds.
+# It expects that you have already created those resources through the appropriate commands.
+# https://docs.getdbt.com/reference/commands/test
+TESTABLE_DBT_RESOURCES = {DbtResourceType.MODEL, DbtResourceType.SOURCE, DbtResourceType.SNAPSHOT, DbtResourceType.SEED}

tests/airflow/test_graph.py

@@ -5,6 +5,7 @@
 import pytest
 from airflow import __version__ as airflow_version
 from airflow.models import DAG
+from airflow.utils.task_group import TaskGroup
 from packaging import version
 
 from cosmos.airflow.graph import (
@@ -13,6 +14,7 @@
     calculate_operator_class,
     create_task_metadata,
     create_test_task_metadata,
+    generate_task_or_group,
 )
 from cosmos.config import ProfileConfig
 from cosmos.constants import DbtResourceType, ExecutionMode, TestBehavior
@@ -101,6 +103,50 @@ def test_build_airflow_graph_with_after_each():
     assert dag.leaves[0].task_id == "child_run"
 
 
+@pytest.mark.parametrize(
+    "node_type,task_suffix",
+    [(DbtResourceType.MODEL, "run"), (DbtResourceType.SEED, "seed"), (DbtResourceType.SNAPSHOT, "snapshot")],
+)
+def test_create_task_group_for_after_each_supported_nodes(node_type, task_suffix):
+    """
+    dbt test runs tests defined on models, sources, snapshots, and seeds.
+    It expects that you have already created those resources through the appropriate commands.
+    https://docs.getdbt.com/reference/commands/test
+    """
+    with DAG("test-task-group-after-each", start_date=datetime(2022, 1, 1)) as dag:
+        node = DbtNode(
+            name="dbt_node",
+            unique_id="dbt_node",
+            resource_type=node_type,
+            file_path=SAMPLE_PROJ_PATH / "gen2/models/parent.sql",
+            tags=["has_child"],
+            config={"materialized": "view"},
+            depends_on=[],
+            has_test=True,
+        )
+    output = generate_task_or_group(
+        dag=dag,
+        task_group=None,
+        node=node,
+        execution_mode=ExecutionMode.LOCAL,
+        task_args={
+            "project_dir": SAMPLE_PROJ_PATH,
+            "profile_config": ProfileConfig(
+                profile_name="default",
+                target_name="default",
+                profile_mapping=PostgresUserPasswordProfileMapping(
+                    conn_id="fake_conn",
+                    profile_args={"schema": "public"},
+                ),
+            ),
+        },
+        test_behavior=TestBehavior.AFTER_EACH,
+        on_warning_callback=None,
+    )
+    assert isinstance(output, TaskGroup)
+    assert list(output.children.keys()) == [f"dbt_node.{task_suffix}", "dbt_node.test"]
+
+
 @pytest.mark.skipif(
     version.parse(airflow_version) < version.parse("2.4"),
     reason="Airflow DAG did not have task_group_dict until the 2.4 release",
@@ -259,7 +305,12 @@ def test_create_task_metadata_seed(caplog, use_task_group):
             args={},
             use_task_group=use_task_group,
         )
-    assert metadata.id == "my_seed_seed"
+
+    if not use_task_group:
+        assert metadata.id == "my_seed_seed"
+    else:
+        assert metadata.id == "seed"
+
     assert metadata.operator_class == "cosmos.operators.docker.DbtSeedDockerOperator"
     assert metadata.arguments == {"models": "my_seed"}
 
@@ -280,14 +331,32 @@ def test_create_task_metadata_snapshot(caplog):
     assert metadata.arguments == {"models": "my_snapshot"}
 
 
-def test_create_test_task_metadata():
+@pytest.mark.parametrize(
+    "node_type,node_unique_id,selector_key,selector_value",
+    [
+        (DbtResourceType.MODEL, "node_name", "models", "node_name"),
+        (DbtResourceType.SEED, "node_name", "select", "node_name"),
+        (DbtResourceType.SOURCE, "source.node_name", "select", "source:node_name"),
+        (DbtResourceType.SNAPSHOT, "node_name", "select", "node_name"),
+    ],
+)
+def test_create_test_task_metadata(node_type, node_unique_id, selector_key, selector_value):
+    sample_node = DbtNode(
+        name="node_name",
+        unique_id=node_unique_id,
+        resource_type=node_type,
+        depends_on=[],
+        file_path="",
+        tags=[],
+        config={},
+    )
     metadata = create_test_task_metadata(
         test_task_name="test_no_nulls",
         execution_mode=ExecutionMode.LOCAL,
         task_args={"task_arg": "value"},
         on_warning_callback=True,
-        model_name="my_model",
+        node=sample_node,
     )
     assert metadata.id == "test_no_nulls"
     assert metadata.operator_class == "cosmos.operators.local.DbtTestLocalOperator"
-    assert metadata.arguments == {"task_arg": "value", "on_warning_callback": True, "models": "my_model"}
+    assert metadata.arguments == {"task_arg": "value", "on_warning_callback": True, selector_key: selector_value}