convert 027 cycle test

tests/functional/cycles/test_cycles.py

@@ -0,0 +1,71 @@
+import pytest
+
+from dbt.tests.util import run_dbt
+
+model_a_sql = """
+select * from {{ ref('model_b') }}
+"""
+
+model_b_sql = """
+select * from {{ ref('model_a') }}
+"""
+
+complex_cycle__model_a_sql = """
+select 1 as id
+"""
+
+complex_cycle__model_b_sql = """
+select * from {{ ref('model_a') }}s
+union all
+select * from {{ ref('model_e') }}
+"""
+
+complex_cycle__model_c_sql = """
+select * from {{ ref('model_b') }}
+"""
+
+complex_cycle__model_d_sql = """
+select * from {{ ref('model_c') }}
+"""
+
+complex_cycle__model_e_sql = """
+select * from {{ ref('model_e') }}
+"""
+
+
+class TestSimpleCycle:
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "model_a.sql": model_a_sql,
+            "model_b.sql": model_b_sql
+        }
+
+    def test_postgres_simple_cycle(self, project):
+        with pytest.raises(RuntimeError) as exc:
+            run_dbt(["run"], expect_pass=False)
+        expected_msg = "Found a cycle"
+        assert expected_msg in str(exc.value)
+
+
+class TestComplexCycle:
+    @pytest.fixture(scope="class")
+    def models(self):
+        # The cycle in this graph looks like:
+        #   A -> B -> C -> D
+        #        ^         |
+        #        |         |
+        #        +--- E <--+
+        return {
+            "model_a.sql": complex_cycle__model_a_sql,
+            "model_b.sql": complex_cycle__model_b_sql,
+            "model_c.sql": complex_cycle__model_c_sql,
+            "model_d.sql": complex_cycle__model_d_sql,
+            "model_e.sql": complex_cycle__model_e_sql,
+        }
+
+    def test_postgres_complex_cycle(self, project):
+        with pytest.raises(RuntimeError) as exc:
+            run_dbt(["run"], expect_pass=False)
+        expected_msg = "Found a cycle"
+        assert expected_msg in str(exc.value)