Add test coverage for the contextlib API (#1458)

betty/tests/test_contextlib.py

@@ -0,0 +1,52 @@
+from __future__ import annotations
+
+from contextlib import suppress
+from types import TracebackType
+
+from betty.contextlib import SynchronizedContextManager
+
+
+class DummyAsynchronousContextManager:
+    def __init__(self):
+        self.entered = False
+        self.exited = False
+        self.exc_type: type[BaseException] | None = None
+        self.exc_val: BaseException | None = None
+        self.exc_tb: TracebackType | None = None
+
+    async def __aenter__(self):
+        self.entered = True
+
+    async def __aexit__(
+        self,
+        exc_type: type[BaseException] | None,
+        exc_val: BaseException | None,
+        exc_tb: TracebackType | None,
+    ) -> None:
+        self.exited = True
+        self.exc_type = exc_type
+        self.exc_val = exc_val
+        self.exc_tb = exc_tb
+
+
+class TestSynchronizedContextManager:
+    async def test(self) -> None:
+        asynchronous_context_manager = DummyAsynchronousContextManager()
+        sut = SynchronizedContextManager(asynchronous_context_manager)
+        with sut:
+            pass
+        assert asynchronous_context_manager.entered
+        assert asynchronous_context_manager.exited
+
+    async def test_with_error(self) -> None:
+        asynchronous_context_manager = DummyAsynchronousContextManager()
+        sut = SynchronizedContextManager(asynchronous_context_manager)
+        error = RuntimeError()
+        with suppress(RuntimeError):
+            with sut:
+                raise error
+        assert asynchronous_context_manager.entered
+        assert asynchronous_context_manager.exited
+        assert asynchronous_context_manager.exc_type is RuntimeError
+        assert asynchronous_context_manager.exc_val is error
+        assert asynchronous_context_manager.exc_tb is error.__traceback__