Fix race condition: remove global cache clearing that caused parallel test hangs

The cache clearing after seed() was causing race conditions because all
parallel test workers (gw0-gw7) share the same project_dir_copy directory.
When one worker cleared target/schemas while another was using it, the
other worker would hang.

Changes:
- Remove _clear_fusion_schema_cache_if_needed() from seed()
- Re-add skip_for_dbt_fusion marker to test_schema_changes
- Remove unused shutil import

Co-Authored-By: Itamar Hartstein <haritamar@gmail.com>

Author: devin-ai-integration[bot]

integration_tests/tests/dbt_project.py

@@ -1,6 +1,5 @@
 import json
 import os
-import shutil
 from contextlib import contextmanager, nullcontext
 from pathlib import Path
 from tempfile import NamedTemporaryFile
@@ -262,20 +261,6 @@ def seed(self, data: List[dict], table_name: str):
             self.dbt_runner, self.project_dir_path, self.seeds_dir_path
         ).seed(data, table_name):
             self._fix_seed_if_needed(table_name)
-            self._clear_fusion_schema_cache_if_needed()
-
-    def _clear_fusion_schema_cache_if_needed(self):
-        """Clear dbt-fusion's schema cache after seeding.
-
-        dbt-fusion caches column information for relations. When a table is recreated
-        with different columns (e.g., in test_schema_changes), the cache becomes stale.
-        Clearing the cache after seeding ensures the next get_columns_in_relation call
-        queries the warehouse for fresh column information.
-        """
-        if self.runner_method == RunnerMethod.FUSION:
-            schema_cache_path = self.project_dir_path / "target" / "schemas"
-            if schema_cache_path.exists():
-                shutil.rmtree(schema_cache_path, ignore_errors=True)
 
     def _fix_seed_if_needed(self, table_name: str):
         # Hack for BigQuery - seems like we get empty strings instead of nulls in seeds, so we

integration_tests/tests/test_schema_changes.py

@@ -42,7 +42,9 @@ def assert_test_results(test_results: List[dict]):
 
 
 # Schema changes currently not supported on targets
+# dbt-fusion caches column information and doesn't refresh when tables are recreated
 @pytest.mark.skip_targets(["databricks", "spark", "athena", "trino", "clickhouse"])
+@pytest.mark.skip_for_dbt_fusion
 def test_schema_changes(test_id: str, dbt_project: DbtProject):
     dbt_test_name = "elementary.schema_changes"
     test_result = dbt_project.test(test_id, dbt_test_name, data=DATASET1)