Fallback to blocking subprocess.run if using SelectorEventLoop type

src/pixi_kernel/pixi.py

@@ -2,8 +2,9 @@
 
 import logging
 import shutil
-from asyncio import create_subprocess_exec
-from asyncio.subprocess import PIPE, Process
+import subprocess
+from asyncio import SelectorEventLoop, create_subprocess_exec, get_event_loop
+from asyncio.subprocess import PIPE
 from pathlib import Path
 from typing import Any, Optional
 
@@ -32,11 +33,18 @@ class Project(BaseModel):
     manifest_path: str
 
 
-async def subprocess_exec(program: str, *args: str, **kwargs: Any) -> tuple[Process, str, str]:
-    process = await create_subprocess_exec(program, *args, stdout=PIPE, stderr=PIPE, **kwargs)
-    stdout_bytes, stderr_bytes = await process.communicate()
-    stdout, stderr = stdout_bytes.decode("utf-8"), stderr_bytes.decode("utf-8")
-    return process, stdout, stderr
+async def subprocess_exec(program: str, *args: str, **kwargs: Any) -> tuple[int, str, str]:
+    # The SelectorEventLoop does not support asyncio.subprocess
+    # https://github.com/renan-r-santos/pixi-kernel/issues/39
+    if isinstance(get_event_loop(), SelectorEventLoop):
+        result = subprocess.run([program, *args], capture_output=True, text=True, **kwargs)  # noqa: ASYNC221
+        return result.returncode, result.stdout, result.stderr
+    else:
+        process = await create_subprocess_exec(program, *args, stdout=PIPE, stderr=PIPE, **kwargs)
+        stdout_bytes, stderr_bytes = await process.communicate()
+        assert process.returncode is not None
+        stdout, stderr = stdout_bytes.decode("utf-8"), stderr_bytes.decode("utf-8")
+        return process.returncode, stdout, stderr
 
 
 async def ensure_readiness(
@@ -69,8 +77,8 @@ async def ensure_readiness(
         raise RuntimeError(PIXI_NOT_FOUND.format(kernel_name=kernel_name))
 
     # Ensure a supported Pixi version is installed
-    process, stdout, stderr = await subprocess_exec("pixi", "--version", env=env)
-    if process.returncode != 0 or not stdout.startswith("pixi "):
+    returncode, stdout, stderr = await subprocess_exec("pixi", "--version", env=env)
+    if returncode != 0 or not stdout.startswith("pixi "):
         raise RuntimeError(PIXI_VERSION_ERROR.format(kernel_name=kernel_name))
 
     # Parse Pixi version and check it against the minimum required version
@@ -85,11 +93,11 @@ async def ensure_readiness(
         )
 
     # Ensure there is a Pixi project in the current working directory or any of its parents
-    process, stdout, stderr = await subprocess_exec("pixi", "info", "--json", cwd=cwd, env=env)
+    returncode, stdout, stderr = await subprocess_exec("pixi", "info", "--json", cwd=cwd, env=env)
 
     logger.info(f"pixi info stderr: {stderr}")
     logger.info(f"pixi info stdout: {stdout}")
-    if process.returncode != 0:
+    if returncode != 0:
         raise RuntimeError(f"Failed to run 'pixi info': {stderr}")
 
     try:
@@ -102,7 +110,7 @@ async def ensure_readiness(
     if pixi_info.project is None:
         # Attempt to get a good error message by running `pixi project version get`. Maybe there's
         # a typo in the toml file (parsing error) or there is no project at all.
-        process, stdout, stderr = await subprocess_exec(
+        returncode, stdout, stderr = await subprocess_exec(
             "pixi",
             "project",
             "version",
@@ -131,8 +139,8 @@ async def ensure_readiness(
         )
 
     # Make sure the environment can be solved and is up-to-date
-    process, stdout, stderr = await subprocess_exec("pixi", "install", cwd=cwd, env=env)
-    if process.returncode != 0:
+    returncode, stdout, stderr = await subprocess_exec("pixi", "install", cwd=cwd, env=env)
+    if returncode != 0:
         raise RuntimeError(f"Failed to run 'pixi install': {stderr}")
 
     return default_environment

src/pixi_kernel/provisioner.py

@@ -34,7 +34,7 @@ async def pre_launch(self, **kwargs: Any) -> dict[str, Any]:
         logger.info(f"JupyterLab provided this value for cwd: {kwargs.get('cwd', None)}")
         logger.info(f"The current working directory is {cwd}")
 
-        env: dict[str, str] = kwargs.get("env", os.environ)
+        env: dict[str, str] = kwargs.get("env", os.environ.copy())
         pixi_environment = await ensure_readiness(
             cwd=cwd.resolve(),
             env=env,

tests/unit/conftest.py

@@ -1,14 +1,23 @@
+import asyncio
 import json
-from dataclasses import dataclass
+import platform
 
 import pytest
 
 import pixi_kernel.pixi
 
-
-@dataclass
-class MockProcessResult:
-    returncode: int
+if platform.system() == "Windows":
+    # Test both event loop policies on Windows
+    # https://github.com/renan-r-santos/pixi-kernel/issues/39
+    @pytest.fixture(
+        scope="session",
+        params=(
+            asyncio.WindowsSelectorEventLoopPolicy(),
+            asyncio.WindowsProactorEventLoopPolicy(),
+        ),
+    )
+    def event_loop_policy(request: pytest.FixtureRequest):
+        return request.param
 
 
 @pytest.fixture
@@ -22,7 +31,7 @@ def _patch_pixi_version_exit_code(monkeypatch: pytest.MonkeyPatch):
 
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("--version",):
-            return MockProcessResult(1), "", ""
+            return 1, "", ""
         else:
             return await orig_subprocess_exec(cmd, *args, **kwargs)
 
@@ -35,7 +44,7 @@ def _patch_pixi_version_stdout(monkeypatch: pytest.MonkeyPatch):
 
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("--version",):
-            return MockProcessResult(0), "wrong output", ""
+            return 0, "wrong output", ""
         else:
             return await orig_subprocess_exec(cmd, *args, **kwargs)
 
@@ -48,12 +57,12 @@ def _patch_pixi_version(monkeypatch: pytest.MonkeyPatch):
 
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("--version",):
-            process, stdout, stderr = await orig_subprocess_exec(cmd, *args, **kwargs)
-            assert process.returncode == 0
+            returncode, stdout, stderr = await orig_subprocess_exec(cmd, *args, **kwargs)
+            assert returncode == 0
             assert stdout.startswith("pixi ")
 
             stdout = "pixi 0.15.0\n"
-            return process, stdout, stderr
+            return returncode, stdout, stderr
         else:
             return await orig_subprocess_exec(cmd, *args, **kwargs)
 
@@ -66,7 +75,7 @@ def _patch_pixi_info_exit_code(monkeypatch: pytest.MonkeyPatch):
 
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("info", "--json"):
-            return MockProcessResult(1), "", "error"
+            return 1, "", "error"
         else:
             return await orig_subprocess_exec(cmd, *args, **kwargs)
 
@@ -79,7 +88,7 @@ def _patch_pixi_info_stdout(monkeypatch: pytest.MonkeyPatch):
 
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("info", "--json"):
-            return MockProcessResult(0), "not JSON", ""
+            return 0, "not JSON", ""
         else:
             return await orig_subprocess_exec(cmd, *args, **kwargs)
 
@@ -93,7 +102,7 @@ def _patch_pixi_info_no_default_env(monkeypatch: pytest.MonkeyPatch):
     async def mock_subprocess_exec(cmd, *args, **kwargs):
         if cmd == "pixi" and args == ("info", "--json"):
             return (
-                MockProcessResult(0),
+                0,
                 json.dumps(
                     {
                         "project_info": {"manifest_path": "/"},

tests/unit/test_pixi.py

@@ -178,8 +178,8 @@ async def test_pyproject_project():
 @pytest.fixture
 async def env_for_pixi_in_pixi():
     cwd = data_dir / "pixi_in_pixi"
-    process, stdout, stderr = await subprocess_exec("pixi", "run", "printenv", cwd=cwd)
-    assert process.returncode == 0, stderr
+    returncode, stdout, stderr = await subprocess_exec("pixi", "run", "printenv", cwd=cwd)
+    assert returncode == 0, stderr
 
     # Update the current environment where the tests are running to merge all the env vars returned
     # by `pixi run env`