feat(pems_data): factory composes services

Author: thekaveman

pems_data/src/pems_data/__init__.py

@@ -0,0 +1,21 @@
+from pems_data.cache import Cache
+from pems_data.services.stations import StationsService
+from pems_data.sources.cache import CachingDataSource
+from pems_data.sources.s3 import S3DataSource
+
+
+class ServiceFactory:
+    """
+    A factory class to create and configure various services.
+
+    Shared dependencies are created once during initialization.
+    """
+
+    def __init__(self):
+        self.cache = Cache()
+        self.s3_source = S3DataSource()
+        self.caching_s3_source = CachingDataSource(data_source=self.s3_source, cache=self.cache)
+
+    def stations_service(self) -> StationsService:
+        """Creates a fully-configured `StationsService`."""
+        return StationsService(data_source=self.caching_s3_source)

tests/pytest/pems_data/conftest.py

@@ -5,3 +5,16 @@
 @pytest.fixture
 def df() -> pd.DataFrame:
     return pd.DataFrame({"col1": [1, 2, 3], "col2": ["a", "b", "c"]})
+
+
+@pytest.fixture(autouse=True)
+def mock_s3(mocker):
+    s3 = mocker.patch("boto3.client").return_value
+    s3.list_objects.return_value = {
+        "Contents": [
+            {"Key": "path1/file2.json"},
+            {"Key": "path2/file1.json"},
+            {"Key": "path1/file1.json"},
+        ]
+    }
+    return s3

tests/pytest/pems_data/sources/test_s3.py

@@ -11,18 +11,6 @@ class TestS3DataSource:
     def data_source(self) -> S3DataSource:
         return S3DataSource()
 
-    @pytest.fixture(autouse=True)
-    def mock_s3(self, mocker):
-        s3 = mocker.patch("boto3.client").return_value
-        s3.list_objects.return_value = {
-            "Contents": [
-                {"Key": "path1/file2.json"},
-                {"Key": "path2/file1.json"},
-                {"Key": "path1/file1.json"},
-            ]
-        }
-        return s3
-
     @pytest.fixture(autouse=True)
     def mock_read_parquet(self, mocker):
         return mocker.patch("pandas.read_parquet")

tests/pytest/pems_data/test_init.py

@@ -0,0 +1,31 @@
+import pytest
+
+from pems_data import ServiceFactory
+from pems_data.cache import Cache
+from pems_data.services.stations import StationsService
+from pems_data.sources.cache import CachingDataSource
+from pems_data.sources.s3 import S3DataSource
+
+
+class TestServiceFactory:
+
+    @pytest.fixture
+    def factory(self):
+        return ServiceFactory()
+
+    def test_init_cache(self, factory: ServiceFactory):
+        assert isinstance(factory.cache, Cache)
+
+    def test_init_s3_source(self, factory: ServiceFactory):
+        assert isinstance(factory.s3_source, S3DataSource)
+
+    def test_init_caching_s3_source(self, factory: ServiceFactory):
+        assert isinstance(factory.caching_s3_source, CachingDataSource)
+        assert isinstance(factory.caching_s3_source.data_source, S3DataSource)
+        assert isinstance(factory.caching_s3_source.cache, Cache)
+
+    def test_stations_service(self, factory: ServiceFactory):
+        service = factory.stations_service()
+
+        assert isinstance(service, StationsService)
+        assert service.data_source == factory.caching_s3_source