fix(plugins/python): output error messages to stderr

Properly redirect error messages instead of using the combined stream output. Signed-off-by: Claudio Matsuoka <[email protected]>
canonical · Feb 11, 2025 · 522e316 · 522e316
1 parent b4f5ca6
commit 522e316
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Showing 6 changed files with 29 additions and 16 deletions.
diff --git a/craft_parts/executor/step_handler.py b/craft_parts/executor/step_handler.py
@@ -156,7 +156,7 @@ def _builtin_build(self) -> StepContents:
             raise errors.PluginBuildError(
                 part_name=self._part.name,
                 plugin_name=self._part.plugin_name,
-                stderr=process_error.result.combined,
+                stderr=process_error.result.stderr,
             ) from process_error
 
         return StepContents()
@@ -296,7 +296,7 @@ def run_scriptlet(
                     part_name=self._part.name,
                     scriptlet_name=scriptlet_name,
                     exit_code=process_error.result.returncode,
-                    stderr=process_error.result.combined,
+                    stderr=process_error.result.stderr,
                 ) from process_error
             finally:
                 ctl_socket.close()

diff --git a/craft_parts/plugins/base.py b/craft_parts/plugins/base.py
@@ -179,12 +179,12 @@ def _get_find_python_interpreter_commands(self) -> list[str]:
                 fi
             else
                 # Otherwise use what _get_system_python_interpreter() told us.
-                echo "Python interpreter not found in payload."
+                echo "Python interpreter not found in payload." >&2
                 symlink_target="{python_interpreter}"
             fi
 
             if [ -z "$symlink_target" ]; then
-                echo "No suitable Python interpreter found, giving up."
+                echo "No suitable Python interpreter found, giving up." >&2
                 exit 1
             fi
 

diff --git a/tests/integration/plugins/test_poetry.py b/tests/integration/plugins/test_poetry.py
@@ -242,15 +242,21 @@ def _get_system_python_interpreter(self) -> str | None:
     actions = lf.plan(Step.PRIME)
 
     out = pathlib.Path("out.txt")
-    with out.open(mode="w") as outfile, pytest.raises(errors.PluginBuildError):
+    with out.open(mode="w") as outfile, err.open(mode="w") as errfile, pytest.raises(errors.PluginBuildError):
         with lf.action_executor() as ctx:
-            ctx.execute(actions, stdout=outfile)
+            ctx.execute(actions, stdout=outfile, stderr=errfile)
 
     output = out.read_text()
     expected_text = textwrap.dedent(
         f"""\
         Looking for a Python interpreter called "{real_basename}" in the payload...
-        Python interpreter not found in payload.
+        """
+    )
+    assert expected_text in output
+
+    output = err.read_text()
+    expected_text = textwrap.dedent(
+        f"""\
         No suitable Python interpreter found, giving up.
         """
     )

diff --git a/tests/integration/plugins/test_python.py b/tests/integration/plugins/test_python.py
@@ -322,15 +322,22 @@ def _get_system_python_interpreter(self) -> str | None:
     actions = lf.plan(Step.PRIME)
 
     out = Path("out.txt")
-    with out.open(mode="w") as outfile, pytest.raises(errors.PluginBuildError):
+    err = Path("err.txt")
+    with out.open(mode="w") as outfile, err.open(mode="w") as errfile, pytest.raises(errors.PluginBuildError):
         with lf.action_executor() as ctx:
-            ctx.execute(actions, stdout=outfile)
+            ctx.execute(actions, stdout=outfile, stderr=errfile)
 
     output = out.read_text()
     expected_text = textwrap.dedent(
         f"""\
         Looking for a Python interpreter called "{real_basename}" in the payload...
-        Python interpreter not found in payload.
+        """
+    )
+    assert expected_text in output
+
+    output = err.read_text()
+    expected_text = textwrap.dedent(
+        f"""\
         No suitable Python interpreter found, giving up.
         """
     )

diff --git a/tests/unit/plugins/test_base.py b/tests/unit/plugins/test_base.py
@@ -161,12 +161,12 @@ def test_python_get_find_python_interpreter_commands(
                 fi
             else
                 # Otherwise use what _get_system_python_interpreter() told us.
-                echo "Python interpreter not found in payload."
+                echo "Python interpreter not found in payload." >&2
                 symlink_target="$(readlink -f "$(which "${{PARTS_PYTHON_INTERPRETER}}")")"
             fi
 
             if [ -z "$symlink_target" ]; then
-                echo "No suitable Python interpreter found, giving up."
+                echo "No suitable Python interpreter found, giving up." >&2
                 exit 1
             fi
 
@@ -253,12 +253,12 @@ def test_python_get_build_commands(new_dir, python_plugin: FooPythonPlugin):
                 fi
             else
                 # Otherwise use what _get_system_python_interpreter() told us.
-                echo "Python interpreter not found in payload."
+                echo "Python interpreter not found in payload." >&2
                 symlink_target="$(readlink -f "$(which "${{PARTS_PYTHON_INTERPRETER}}")")"
             fi
 
             if [ -z "$symlink_target" ]; then
-                echo "No suitable Python interpreter found, giving up."
+                echo "No suitable Python interpreter found, giving up." >&2
                 exit 1
             fi
 

diff --git a/tests/unit/plugins/test_base_python.py b/tests/unit/plugins/test_base_python.py
@@ -87,12 +87,12 @@ def get_python_build_commands(
                 fi
             else
                 # Otherwise use what _get_system_python_interpreter() told us.
-                echo "Python interpreter not found in payload."
+                echo "Python interpreter not found in payload." >&2
                 symlink_target="$(readlink -f "$(which "${{PARTS_PYTHON_INTERPRETER}}")")"
             fi
 
             if [ -z "$symlink_target" ]; then
-                echo "No suitable Python interpreter found, giving up."
+                echo "No suitable Python interpreter found, giving up." >&2
                 exit 1
             fi