Fix pixi cache-dir failure and flaky notebook output check

CHANGELOG.md

@@ -13,6 +13,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - `ewoks convert`: add `--package-manager-name` and `--package-manager-command` arguments.
 - Add `ewoks lint` CLI command to check if a workflow is conform to the Ewoks specification.
 
+### Fixed
+
+- `ewoks install` with the `pixi` package manager: no longer fails when the
+  default cache directory cannot be determined.
+
 ### Removed
 
 - `ewoks install`: remove `-p/--python` argument.

src/ewoks/_requirements/pixi.py

@@ -4,12 +4,14 @@
 import platform
 import re
 import sys
+import tempfile
 from pathlib import Path
 from typing import Dict
 from typing import Literal
 from typing import Mapping
 from typing import Optional
 from typing import Sequence
+from typing import Union
 
 from pydantic import Field
 
@@ -68,6 +70,20 @@ def __init__(self, *command: str) -> None:
             command = ("pixi",)
         super().__init__(*command)
 
+    def _check_output(
+        self,
+        *args: Union[str, Path],
+        extra_env: Optional[Mapping[str, Optional[str]]] = None,
+    ) -> str:
+        return super()._check_output(*args, extra_env=_with_cache_dir(extra_env))
+
+    def _check_call(
+        self,
+        *args: Union[str, Path],
+        extra_env: Optional[Mapping[str, Optional[str]]] = None,
+    ) -> None:
+        super()._check_call(*args, extra_env=_with_cache_dir(extra_env))
+
     def version(self) -> Optional[str]:
         """Returns None when this manager is not available."""
         try:
@@ -172,3 +188,14 @@ def _is_workspace_environment(prefix: Path) -> bool:
     """Environment is managed by a pixi workspace."""
     parts = prefix.parts
     return len(parts) > 2 and parts[-3] == ".pixi" and parts[-2] == "envs"
+
+
+def _with_cache_dir(
+    extra_env: Optional[Mapping[str, Optional[str]]],
+) -> Dict[str, Optional[str]]:
+    env = dict(extra_env) if extra_env else dict()
+    if not os.environ.get("PIXI_CACHE_DIR") and not os.environ.get("RATTLER_CACHE_DIR"):
+        env.setdefault(
+            "PIXI_CACHE_DIR", str(Path(tempfile.gettempdir()) / "pixi-cache")
+        )
+    return env

src/ewoks/tests/test_notebooks.py

@@ -26,11 +26,9 @@ def verify_notebook(tb: TestbookNotebookClient) -> None:
             tb.execute()
 
             nonlocal output_found
-            for output in _iter_cell_outputs(tb):
-                print(output)
-                if expected_output in output:
-                    output_found = True
-                    break
+            all_output = "".join(_iter_cell_outputs(tb))
+            print(all_output)
+            output_found = expected_output in all_output
 
         decorator(verify_notebook)()