extract_declared_dependencies: Handle exceptions due to invalid toml

When parsing a pyproject.toml or pixi.toml with invalid TOML data, the
tomllib parser will raise an exception that is not properly caught or
handled by FawltyDeps.

Fix this by logging an error message and returning from the parse
function. This allows FawltyDeps to continue parsing other files and
reporting undeclared/unused dependencies, whereas before it would abort
with a traceback.

fawltydeps/extract_declared_dependencies.py

@@ -415,7 +415,11 @@ def parse_pyproject_toml(path: Path) -> Iterator[DeclaredDependency]:
     """
     source = Location(path)
     with path.open("rb") as tomlfile:
-        parsed_contents = tomllib.load(tomlfile)
+        try:
+            parsed_contents = tomllib.load(tomlfile)
+        except tomllib.TOMLDecodeError as e:
+            logger.error(f"Failed to parse {source}: {e}")
+            return
 
     skip = set()
 
@@ -457,7 +461,11 @@ def parse_pixi_toml(path: Path) -> Iterator[DeclaredDependency]:
     """
     source = Location(path)
     with path.open("rb") as tomlfile:
-        parsed_contents = tomllib.load(tomlfile)
+        try:
+            parsed_contents = tomllib.load(tomlfile)
+        except tomllib.TOMLDecodeError as e:
+            logger.error(f"Failed to parse {source}: {e}")
+            return
 
     skip = set()
 

tests/test_extract_declared_dependencies_pixi_toml.py

@@ -159,6 +159,18 @@ def test_parse_pixi_toml__wellformed_dependencies__yields_dependencies(
     assert result == expected
 
 
+def test_parse_pixi_toml__invalid_toml__yields_no_deps_and_error_message(
+    write_tmp_files, caplog
+):
+    tmp_path = write_tmp_files({"pixi.toml": "[this is not valid toml\n"})
+    path = tmp_path / "pixi.toml"
+
+    caplog.set_level(logging.ERROR)
+    result = list(parse_pixi_toml(path))
+    assert result == []
+    assert f"Failed to parse {path}:" in caplog.text
+
+
 @dataclass
 class PixiTestVector:
     """Test vectors for parsing of malformed pixi.toml."""

tests/test_extract_declared_dependencies_pyproject_toml.py

@@ -353,6 +353,18 @@ def test_parse_pyproject_toml__wellformed_dependencies__yields_dependencies(
     assert result == expected
 
 
+def test_parse_pyproject_toml__invalid_toml__yields_no_deps_and_error_message(
+    write_tmp_files, caplog
+):
+    tmp_path = write_tmp_files({"pyproject.toml": "[this is not valid toml\n"})
+    path = tmp_path / "pyproject.toml"
+
+    caplog.set_level(logging.ERROR)
+    result = list(parse_pyproject_toml(path))
+    assert result == []
+    assert f"Failed to parse {path}:" in caplog.text
+
+
 @dataclass
 class PyprojectTestVector:
     """Test vectors for parsing of malformed pyproject.toml."""