Add context manager tests

uv.lock

@@ -4,7 +4,7 @@ requires-python = ">=3.13"
 
 [[package]]
 name = "breakshaft"
-version = "0.1.0.post1"
+version = "0.1.0.post2"
 source = { editable = "." }
 dependencies = [
     { name = "hatchling" },
@@ -15,6 +15,7 @@ dependencies = [
 dev = [
     { name = "mypy" },
     { name = "pytest" },
+    { name = "pytest-asyncio" },
     { name = "pytest-cov" },
 ]
 
@@ -28,6 +29,7 @@ requires-dist = [
 dev = [
     { name = "mypy", specifier = ">=1.16.1" },
     { name = "pytest", specifier = ">=8.4.1" },
+    { name = "pytest-asyncio", specifier = ">=1.1.0" },
     { name = "pytest-cov", specifier = ">=6.2.1" },
 ]
 
@@ -216,6 +218,18 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/29/16/c8a903f4c4dffe7a12843191437d7cd8e32751d5de349d45d3fe69544e87/pytest-8.4.1-py3-none-any.whl", hash = "sha256:539c70ba6fcead8e78eebbf1115e8b589e7565830d7d006a8723f19ac8a0afb7", size = 365474, upload-time = "2025-06-18T05:48:03.955Z" },
 ]
 
+[[package]]
+name = "pytest-asyncio"
+version = "1.1.0"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "pytest" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/4e/51/f8794af39eeb870e87a8c8068642fc07bce0c854d6865d7dd0f2a9d338c2/pytest_asyncio-1.1.0.tar.gz", hash = "sha256:796aa822981e01b68c12e4827b8697108f7205020f24b5793b3c41555dab68ea", size = 46652, upload-time = "2025-07-16T04:29:26.393Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/c7/9d/bf86eddabf8c6c9cb1ea9a869d6873b46f105a5d292d3a6f7071f5b07935/pytest_asyncio-1.1.0-py3-none-any.whl", hash = "sha256:5fe2d69607b0bd75c656d1211f969cadba035030156745ee09e7d71740e58ecf", size = 15157, upload-time = "2025-07-16T04:29:24.929Z" },
+]
+
 [[package]]
 name = "pytest-cov"
 version = "6.2.1"