refactor: Make calls to datasource async

Co-authored-by: Adam Gardner <adam.gardner@armakuni.com>

pyproject.toml

@@ -23,6 +23,7 @@ ruff = "^0.0.276"
 mypy = "^1.4.0"
 pytest = "^7.3.2"
 wiremock = "^2.5.0"
+pytest-asyncio = "^0.21.0"
 
 [build-system]
 requires = ["poetry-core"]

src/cli/async_helper.py

@@ -0,0 +1,12 @@
+import asyncio
+from typing import Callable, Coroutine, ParamSpec, TypeVar
+
+P = ParamSpec("P")
+R = TypeVar("R")
+
+
+def async_to_sync(f: Callable[P, Coroutine[None, None, R]]) -> Callable[P, R]:
+    def inner(*args: P.args, **kwargs: P.kwargs) -> R:
+        return asyncio.run(f(*args, **kwargs))
+
+    return inner

src/cli/parsers.py

@@ -0,0 +1,5 @@
+from httpx import URL
+
+
+def parse_url(url: str) -> URL:
+    return URL(url)

src/main.py

@@ -3,6 +3,9 @@
 
 from httpx import URL
 
+from src.cli.async_helper import async_to_sync
+from src.cli.parsers import parse_url
+
 UK_CARBON_INTENSITY_API_BASE_URL: URL = URL("https://api.carbonintensity.org.uk")
 FILE_FOR_INTENSITY_READING: str = ".carbon_intensity"
 
@@ -21,10 +24,6 @@ class DataSource(StrEnum):
     UK_CARBON_INTENSITY = "uk-carbon-intensity"
 
 
-def parse_url(url: str) -> URL:
-    return URL(url)
-
-
 def main(
     max_carbon_intensity: Annotated[
         int,
@@ -56,23 +55,35 @@ def main(
             parser=parse_url,
         ),
     ] = UK_CARBON_INTENSITY_API_BASE_URL,
+) -> None:
+    carbon_intensity(
+        data_source,
+        from_file_carbon_intensity_file_path,
+        max_carbon_intensity,
+        uk_carbon_intensity_api_base_url,
+    )
+
+
+@async_to_sync
+async def carbon_intensity(
+    data_source: DataSource,
+    from_file_carbon_intensity_file_path: Path,
+    max_carbon_intensity: int,
+    uk_carbon_intensity_api_base_url: URL,
 ) -> None:
     intensity_repo: CarbonIntensityRepo = FromFileCarbonIntensityRepo(
         from_file_carbon_intensity_file_path
     )
-
     match data_source:
         case DataSource.FILE:
             intensity_repo = intensity_repo
         case DataSource.UK_CARBON_INTENSITY:
             intensity_repo = UkCarbonIntensityApiRepo(
                 base_url=uk_carbon_intensity_api_base_url
             )
-
-    if intensity_repo.get_carbon_intensity() > max_carbon_intensity:
+    if await intensity_repo.get_carbon_intensity() > max_carbon_intensity:
         typer.echo("Carbon levels exceed threshold, skipping.")
         raise typer.Exit(1)
-
     typer.echo("Carbon levels under threshold, proceeding.")
 
 

src/repos/carbon_intensity.py

@@ -1,28 +1,28 @@
 from pathlib import Path
 from typing import Protocol
 
-from httpx import URL, Client
+from httpx import URL, AsyncClient
 from pydantic import BaseModel, field_validator
 
 
 class CarbonIntensityRepo(Protocol):
-    def get_carbon_intensity(self) -> int:
+    async def get_carbon_intensity(self) -> int:
         ...
 
 
 class InMemoryCarbonIntensityRepo(object):
     def __init__(self, carbon_intensity: int) -> None:
         self._carbon_intensity = carbon_intensity
 
-    def get_carbon_intensity(self) -> int:
+    async def get_carbon_intensity(self) -> int:
         return self._carbon_intensity
 
 
 class FromFileCarbonIntensityRepo(object):
     def __init__(self, file_path: Path) -> None:
         self._file_path = file_path
 
-    def get_carbon_intensity(self) -> int:
+    async def get_carbon_intensity(self) -> int:
         return int(self._file_path.read_text(encoding="utf8"))
 
 
@@ -49,10 +49,10 @@ def ensure_data_is_not_empty(
 
 class UkCarbonIntensityApiRepo:
     def __init__(self, base_url: URL):
-        self._client = Client(base_url=base_url, http2=True)
+        self._client = AsyncClient(base_url=base_url, http2=True)
 
-    def get_carbon_intensity(self) -> int:
-        response = self._client.get("/intensity")
+    async def get_carbon_intensity(self) -> int:
+        response = await self._client.get("/intensity")
         response.raise_for_status()
 
         parsed_reponse = UkCarbonIntensityResponse.model_validate_json(response.content)

tests/cli/test_async_helper.py

@@ -0,0 +1,16 @@
+from typing import ParamSpec, TypeVar
+
+from src.cli.async_helper import async_to_sync
+
+P = ParamSpec("P")
+R = TypeVar("R")
+
+
+def test_can_run_async_code_with_annotations() -> None:
+    @async_to_sync
+    async def async_func() -> str:
+        return "hello"
+
+    result = async_func()
+
+    assert result == "hello"

tests/repos/test_carbon_intensity.py

@@ -82,10 +82,14 @@ def carbon_intensity_repo(
     def expected_carbon_intensity(self) -> int:
         return 7
 
-    def test_gives_me_a_global_carbon_intensity_repo(
+    @pytest.mark.asyncio
+    async def test_gives_me_a_global_carbon_intensity_repo(
         self, carbon_intensity_repo: CarbonIntensityRepo, expected_carbon_intensity: int
     ) -> None:
-        assert carbon_intensity_repo.get_carbon_intensity() == expected_carbon_intensity
+        assert (
+            await carbon_intensity_repo.get_carbon_intensity()
+            == expected_carbon_intensity
+        )
 
 
 def test_no_uk_carbon_intensity_data_raises() -> None: