Initial pass at switching integration tests to pytest

.flake8

@@ -8,5 +8,5 @@ ignore =
     W504
     E203 # makes Flake8 work like black
     E741
-max-line-length = 99
+max-line-length = 140
 exclude = test

CHANGELOG.md

@@ -19,6 +19,7 @@
 - Drop support for Python 3.7.0 + 3.7.1 ([#4584](https://github.com/dbt-labs/dbt-core/issues/4584), [#4585](https://github.com/dbt-labs/dbt-core/pull/4585), [#4643](https://github.com/dbt-labs/dbt-core/pull/4643))
 - Re-format codebase (except tests) using pre-commit hooks ([#3195](https://github.com/dbt-labs/dbt-core/issues/3195), [#4697](https://github.com/dbt-labs/dbt-core/pull/4697))
 - Add deps module README ([#4686](https://github.com/dbt-labs/dbt-core/pull/4686/))
+- Initial conversion of tests to pytest ([#4690](https://github.com/dbt-labs/dbt-core/issues/4690), [#4691](https://github.com/dbt-labs/dbt-core/pull/4691))
 
 Contributors:
 - [@NiallRees](https://github.com/NiallRees) ([#4447](https://github.com/dbt-labs/dbt-core/pull/4447))

core/dbt/adapters/factory.py

@@ -177,6 +177,10 @@ def get_adapter(config: AdapterRequiredConfig):
     return FACTORY.lookup_adapter(config.credentials.type)
 
 
+def get_adapter_by_type(adapter_type):
+    return FACTORY.lookup_adapter(adapter_type)
+
+
 def reset_adapters():
     """Clear the adapters. This is useful for tests, which change configs."""
     FACTORY.reset_adapters()

core/dbt/contracts/graph/model_config.py

@@ -389,7 +389,9 @@ class NodeConfig(NodeAndTestConfig):
         metadata=MergeBehavior.Update.meta(),
     )
     full_refresh: Optional[bool] = None
-    unique_key: Optional[Union[str, List[str]]] = None
+    # 'unique_key' doesn't use 'Optional' because typing.get_type_hints was
+    # sometimes getting the Union order wrong, causing serialization failures.
+    unique_key: Union[str, List[str], None] = None
     on_schema_change: Optional[str] = "ignore"
 
     @classmethod

core/dbt/contracts/results.py

@@ -85,6 +85,7 @@ class RunStatus(StrEnum):
 
 
 class TestStatus(StrEnum):
+    __test__ = False
     Pass = NodeStatus.Pass
     Error = NodeStatus.Error
     Fail = NodeStatus.Fail

core/dbt/task/test.py

@@ -230,6 +230,8 @@ class TestTask(RunTask):
         constraints are satisfied.
     """
 
+    __test__ = False
+
     def raise_on_first_error(self):
         return False
 

core/dbt/tests/__init__.py

@@ -0,0 +1 @@
+# dbt.tests directory

core/dbt/tests/fixtures/__init__.py

@@ -0,0 +1 @@
+# dbt.tests.fixtures directory