feat: Add src code excerpt on ruff errors (#996)

tests/formats/dataclass/test_generator.py

@@ -212,10 +212,39 @@ def test_package_name(self):
 
         self.assertEqual("", self.generator.package_name(""))
 
-    def test_format_with_invalid_code(self):
-        src_code = """a = "1"""
+    def test_ruff_code_with_invalid_code(self):
+        src_code = (
+            "class AlternativeText:\n"
+            "    class Meta:\n"
+            '        namespace = "xsdata"\n'
+            "\n"
+            "    foo: Optional[Union[]] = field(\n"
+            "           init=False,\n"
+            '           metadata={"type": "Ignore"}\n'
+            "    )\n"
+            "    bar: str\n"
+            "    thug: str"
+        )
         file_path = Path(__file__)
 
         self.generator.config.output.max_line_length = 55
-        with self.assertRaises(CodegenError):
+        with self.assertRaises(CodegenError) as cm:
             self.generator.ruff_code(src_code, file_path)
+
+        expected = (
+            "\n"
+            "\n"
+            "   class AlternativeText:\n"
+            "       class Meta:\n"
+            '           namespace = "xsdata"\n'
+            "   \n"
+            "--->    foo: Optional[Union[]] = field(\n"
+            "              init=False,\n"
+            '              metadata={"type": "Ignore"}\n'
+            "       )"
+        )
+        self.assertEqual(expected, cm.exception.meta.get("source"))
+
+    def test_code_excerpt_with_no_line_number(self):
+        actual = self.generator.code_excerpt("foobar", "")
+        self.assertEqual("NA", actual)

xsdata/formats/dataclass/generator.py

@@ -1,3 +1,4 @@
+import re
 import subprocess
 from pathlib import Path
 from textwrap import indent
@@ -255,5 +256,25 @@ def ruff_code(self, src_code: str, file_path: Path) -> str:
 
             return src_code_encoded.decode()
         except subprocess.CalledProcessError as e:
-            error = indent(e.stderr.decode(), "  ")
-            raise CodegenError("Ruff failed", details=error)
+            details = e.stderr.decode().replace("error: ", "").strip()
+            source = self.code_excerpt(details, src_code_encoded.decode())
+            raise CodegenError("Ruff failed", details=details, source=source)
+
+    @classmethod
+    def code_excerpt(cls, details: str, src_code: str) -> str:
+        """Extract source code excerpt from the error details message."""
+        match = re.search(r"(\d+):(\d+)", details)
+        if match:
+            line_number = int(match.group(1)) - 1
+            lines = src_code.split("\n")
+            start = max(0, line_number - 4)
+            end = min(len(lines), line_number + 4)
+
+            excerpt = ["\n"]
+            for index in range(start, end):
+                prepend = "--->" if index == line_number else "   "
+                excerpt.append(f"{prepend}{lines[index]}")
+
+            return "\n".join(excerpt)
+
+        return "NA"