Convert threading tests to pytest (#6226)

.changes/unreleased/Under the Hood-20221108-074550.yaml

@@ -0,0 +1,7 @@
+kind: Under the Hood
+body: Convert threading tests to pytest
+time: 2022-11-08T07:45:50.589147-06:00
+custom:
+  Author: stu-k
+  Issue: "5942"
+  PR: "6226"

tests/functional/threading/test_thread_count.py

@@ -0,0 +1,46 @@
+import pytest
+from dbt.tests.util import run_dbt
+
+
+models__do_nothing__sql = """
+with x as (select pg_sleep(1)) select 1
+"""
+
+
+class TestThreadCount:
+    @pytest.fixture(scope="class")
+    def models(self):
+        return {
+            "do_nothing_1.sql": models__do_nothing__sql,
+            "do_nothing_2.sql": models__do_nothing__sql,
+            "do_nothing_3.sql": models__do_nothing__sql,
+            "do_nothing_4.sql": models__do_nothing__sql,
+            "do_nothing_5.sql": models__do_nothing__sql,
+            "do_nothing_6.sql": models__do_nothing__sql,
+            "do_nothing_7.sql": models__do_nothing__sql,
+            "do_nothing_8.sql": models__do_nothing__sql,
+            "do_nothing_9.sql": models__do_nothing__sql,
+            "do_nothing_10.sql": models__do_nothing__sql,
+            "do_nothing_11.sql": models__do_nothing__sql,
+            "do_nothing_12.sql": models__do_nothing__sql,
+            "do_nothing_13.sql": models__do_nothing__sql,
+            "do_nothing_14.sql": models__do_nothing__sql,
+            "do_nothing_15.sql": models__do_nothing__sql,
+            "do_nothing_16.sql": models__do_nothing__sql,
+            "do_nothing_17.sql": models__do_nothing__sql,
+            "do_nothing_18.sql": models__do_nothing__sql,
+            "do_nothing_19.sql": models__do_nothing__sql,
+            "do_nothing_20.sql": models__do_nothing__sql,
+        }
+
+    @pytest.fixture(scope="class")
+    def project_config_update(self):
+        return {"config-version": 2}
+
+    @pytest.fixture(scope="class")
+    def profiles_config_update(self):
+        return {"threads": 2}
+
+    def test_threading_8x(self, project):
+        results = run_dbt(args=["run", "--threads", "16"])
+        assert len(results), 20