Catch malformed config errors gracefully

tests/test_config_parse_errors.py

@@ -0,0 +1,123 @@
+"""Regression tests for malformed-input handling (``ConfigParseError``).
+
+Bug: every parse-layer handler (xml/json/toml/yaml/ini) used to let its
+underlying parser's exception escape as an unhandled traceback when given a
+malformed file. Pointing JinjaTurtle (or Enroll, which calls it as a library)
+at harvested, attacker-influenceable config makes malformed input an entirely
+expected condition, so it must fail cleanly instead of crashing.
+
+These tests pin down that:
+
+  * ``parse_config`` raises the normalised ``ConfigParseError`` for malformed
+    XML/JSON/TOML/INI;
+  * defusedxml's *security* exceptions (XXE / ``EntitiesForbidden``) are NOT
+    swallowed by that normalisation -- they must still propagate so a caller can
+    distinguish "malformed" from "malicious";
+  * an unrelated error (e.g. the TOML "tomllib missing" ``RuntimeError``) is not
+    captured by the normalisation either;
+  * the CLI exits non-zero with a clean message (no traceback) on malformed
+    input; and
+  * folder mode skips an unparseable file instead of aborting the whole run.
+"""
+
+from __future__ import annotations
+
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+from jinjaturtle.core import ConfigParseError, parse_config
+
+
+def _run_cli(args: list[str]) -> subprocess.CompletedProcess[str]:
+    return subprocess.run(
+        [sys.executable, "-m", "jinjaturtle.cli", *args],
+        capture_output=True,
+        text=True,
+    )
+
+
+@pytest.mark.parametrize(
+    "fmt,filename,content",
+    [
+        # Element name is not well-formed XML -> expat ParseError historically
+        # escaped as an uncaught traceback.
+        ("xml", "bad.xml", "<root><{{tag}}/></root>"),
+        ("xml", "bad2.xml", "<root><unclosed></root>"),
+        ("json", "bad.json", "{not valid json"),
+        ("toml", "bad.toml", "x = = ="),
+        # A bare key with no value is invalid INI for configparser.
+        ("ini", "bad.ini", "[s]\nthis line has no equals and no colon\n"),
+    ],
+)
+def test_parse_config_raises_configparseerror_on_malformed(
+    tmp_path: Path, fmt: str, filename: str, content: str
+) -> None:
+    src = tmp_path / filename
+    src.write_text(content, encoding="utf-8")
+    with pytest.raises(ConfigParseError):
+        parse_config(src, fmt=fmt)
+
+
+def test_parse_config_does_not_swallow_xxe_security_exception(tmp_path: Path) -> None:
+    """defusedxml's EntitiesForbidden must propagate, not become ConfigParseError.
+
+    EntitiesForbidden subclasses ValueError, so a naive ``except ValueError`` /
+    ``except Exception`` in parse_config would mask an XXE attempt as a benign
+    "malformed file". The normalisation is deliberately scoped to exclude it.
+    """
+    from defusedxml.common import EntitiesForbidden
+
+    xxe = (
+        '<?xml version="1.0"?>\n'
+        '<!DOCTYPE foo [ <!ENTITY xxe SYSTEM "file:///etc/passwd"> ]>\n'
+        "<foo>&xxe;</foo>\n"
+    )
+    src = tmp_path / "xxe.xml"
+    src.write_text(xxe, encoding="utf-8")
+    with pytest.raises(EntitiesForbidden):
+        parse_config(src, fmt="xml")
+
+
+def test_parse_config_does_not_swallow_unrelated_runtimeerror(
+    tmp_path: Path, monkeypatch
+) -> None:
+    """A non-malformation error (tomllib missing) must propagate unchanged."""
+    import jinjaturtle.handlers.toml as toml_module
+
+    monkeypatch.setattr(toml_module, "tomllib", None)
+    src = tmp_path / "x.toml"
+    src.write_text('a = "b"\n', encoding="utf-8")
+    with pytest.raises(RuntimeError) as exc:
+        parse_config(src, fmt="toml")
+    assert "tomllib/tomli is required" in str(exc.value)
+
+
+def test_cli_fails_cleanly_on_malformed_xml(tmp_path: Path) -> None:
+    """The CLI must exit non-zero with a clean message, not a traceback."""
+    src = tmp_path / "bad.xml"
+    src.write_text("<root><{{tag}}/></root>", encoding="utf-8")
+    res = _run_cli([str(src), "-f", "xml", "-r", "demo"])
+    assert res.returncode != 0
+    # Clean, user-facing message -- not a Python traceback.
+    assert "could not parse" in res.stderr
+    assert "Traceback (most recent call last)" not in res.stderr
+
+
+def test_folder_mode_skips_unparseable_file(tmp_path: Path) -> None:
+    """One malformed file should not abort processing of the whole directory."""
+    from jinjaturtle.multi import process_directory
+
+    good = tmp_path / "good.json"
+    good.write_text('{ "host": "localhost" }', encoding="utf-8")
+    bad = tmp_path / "bad.json"
+    bad.write_text("{not valid json", encoding="utf-8")
+
+    defaults_yaml, outputs = process_directory(tmp_path, False, "demo")
+    # The good file still produced output despite the bad sibling: its content
+    # and source id appear, and a template was generated.
+    assert "localhost" in defaults_yaml
+    assert "good.json" in defaults_yaml
+    assert outputs