fix: warn on contract.enforced=true for materialized_view (#1279)

Upstream dbt does not support contracts on materialized views
(https://docs.getdbt.com/docs/mesh/govern/model-contracts). dbt-databricks
was silently accepting the flag, hiding yml/SQL drift. Now emits a warning
pointing at the dbt docs. Strictly additive; existing build outcomes and
constraint behavior are unchanged.

Co-authored-by: Isaac

Author: sd-db

CHANGELOG.md

@@ -1,3 +1,9 @@
+## dbt-databricks 1.11.8 (TBD)
+
+### Fixes
+
+- Warn when `contract.enforced: true` is set on a `materialized_view` model ([#1279](https://github.com/databricks/dbt-databricks/issues/1279))
+
 ## dbt-databricks 1.11.7 (Apr 17, 2026)
 
 ### Features

dbt/include/databricks/macros/relations/materialized_view/create.sql

@@ -24,6 +24,9 @@
   {%- set model_columns = model.get('columns', {}) -%}
   {%- set contract_config = config.get('contract') -%}
   {%- if contract_config and contract_config.enforced -%}
+    {%- do exceptions.warn(
+         "model '" ~ model.name ~ "' sets contract.enforced=true, but contracts are not supported for materialized_view. See https://docs.getdbt.com/docs/mesh/govern/model-contracts"
+       ) -%}
     {%- set model_constraints = model.get('constraints', []) -%}
   {%- else -%}
     {%- set model_constraints = [] -%}

tests/functional/adapter/materialized_view_tests/test_contract.py

@@ -0,0 +1,104 @@
+"""Tests for contract handling on materialized_view models. See #1279."""
+
+import pytest
+from dbt.tests import util
+
+
+MY_SEED = """
+id,value
+1,100
+2,200
+3,300
+""".strip()
+
+
+MV_CONTRACT_ENFORCED_SQL = """
+{{ config(materialized='materialized_view') }}
+select id, value from {{ ref('my_seed') }}
+"""
+
+MV_CONTRACT_ENFORCED_SCHEMA = """
+version: 2
+
+models:
+  - name: mv_contract_enforced
+    config:
+      contract:
+        enforced: true
+    columns:
+      - name: id
+        data_type: bigint
+      - name: value
+        data_type: bigint
+"""
+
+
+MV_NOT_NULL_SQL = """
+{{ config(materialized='materialized_view') }}
+select
+    case when id = 2 then cast(null as bigint) else id end as id,
+    value
+from {{ ref('my_seed') }}
+"""
+
+MV_NOT_NULL_SCHEMA = """
+version: 2
+
+models:
+  - name: mv_not_null
+    columns:
+      - name: id
+        data_type: bigint
+        constraints:
+          - type: not_null
+      - name: value
+        data_type: bigint
+"""
+
+
+@pytest.mark.dlt
+@pytest.mark.skip_profile("databricks_cluster", "databricks_uc_cluster")
+class TestMVContractEnforcedEmitsWarning:
+    @pytest.fixture(scope="class")
+    def seeds(self):
+        return {"my_seed.csv": MY_SEED}
+
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "mv_contract_enforced.sql": MV_CONTRACT_ENFORCED_SQL,
+            "schema.yml": MV_CONTRACT_ENFORCED_SCHEMA,
+        }
+
+    def test_contract_enforced_warning(self, project):
+        util.run_dbt(["seed"])
+        _, log_output = util.run_dbt_and_capture(
+            ["run", "--select", "mv_contract_enforced"]
+        )
+        assert "contracts are not supported for materialized_view" in log_output.lower()
+        assert "docs.getdbt.com" in log_output.lower()
+
+
+@pytest.mark.dlt
+@pytest.mark.skip_profile("databricks_cluster", "databricks_uc_cluster")
+class TestMVColumnConstraintsAreEnforced:
+    @pytest.fixture(scope="class")
+    def seeds(self):
+        return {"my_seed.csv": MY_SEED}
+
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "mv_not_null.sql": MV_NOT_NULL_SQL,
+            "schema.yml": MV_NOT_NULL_SCHEMA,
+        }
+
+    def test_not_null_constraint_enforced_at_runtime(self, project):
+        util.run_dbt(["seed"])
+        results = util.run_dbt(
+            ["run", "--select", "mv_not_null"],
+            expect_pass=False,
+        )
+        assert len(results) == 1
+        assert results[0].status == "error"
+        assert "NOT_NULL_CONSTRAINT_VIOLATED" in str(results[0].message)