Fix formatting of possible notes added to an Exception (#980)

CHANGELOG.rst

@@ -2,6 +2,7 @@
 =============
 
 - Add support for formatting of ``ExceptionGroup`` errors (`#805 <https://github.com/Delgan/loguru/issues/805>`_).
+- Fix formatting of possible ``__notes__`` attached to an ``Exception`` (`#980 <https://github.com/Delgan/loguru/issues/980>`_).
 
 
 `0.7.1`_ (2023-09-04)

loguru/_better_exceptions.py

@@ -441,7 +441,17 @@ def _format_exception(
         )
         exception_only = traceback.format_exception_only(exc_type, exc_value)
 
-        error_message = exception_only[-1][:-1]  # Remove last new line temporarily
+        # Determining the correct index for the "Exception: message" part in the formatted exception
+        # is challenging. This is because it might be preceded by multiple lines specific to
+        # "SyntaxError" or followed by various notes. However, we can make an educated guess based
+        # on the indentation; the preliminary context for "SyntaxError" is always indented, while
+        # the Exception itself is not. This allows us to identify the correct index for the
+        # exception message.
+        for error_message_index, part in enumerate(exception_only):  # noqa: B007
+            if not part.startswith(" "):
+                break
+
+        error_message = exception_only[error_message_index][:-1]  # Remove last new line temporarily
 
         if self._colorize:
             if ":" in error_message:
@@ -460,7 +470,7 @@ def _format_exception(
 
             error_message = "\n" + error_message
 
-        exception_only[-1] = error_message + "\n"
+        exception_only[error_message_index] = error_message + "\n"
 
         if is_first:
             yield self._prefix

tests/exceptions/output/modern/notes.txt

@@ -0,0 +1,117 @@
+
+Traceback (most recent call last):
+  File "tests/exceptions/source/modern/notes.py", line 13, in <module>
+    raise e
+ValueError: invalid value
+Note
+
+Traceback (most recent call last):
+
+> File "tests/exceptions/source/modern/notes.py", line 13, in <module>
+    raise e
+          └ ValueError('invalid value')
+
+ValueError: invalid value
+Note
+
+Traceback (most recent call last):
+  File "tests/exceptions/source/modern/notes.py", line 20, in <module>
+    raise e
+ValueError: invalid value
+Note1
+Note2
+Note3
+
+
+Traceback (most recent call last):
+
+> File "tests/exceptions/source/modern/notes.py", line 20, in <module>
+    raise e
+          └ ValueError('invalid value')
+
+ValueError: invalid value
+Note1
+Note2
+Note3
+
+
+  + Exception Group Traceback (most recent call last):
+  |   File "tests/exceptions/source/modern/notes.py", line 27, in <module>
+  |     raise e
+  | ExceptionGroup: Grouped (2 sub-exceptions)
+  | Note 1
+  | Note 2
+  | Note 3
+  +-+---------------- 1 ----------------
+    | ValueError: 1
+    +---------------- 2 ----------------
+    | ValueError: 2
+    +------------------------------------
+
+  + Exception Group Traceback (most recent call last):
+  |
+  | > File "tests/exceptions/source/modern/notes.py", line 27, in <module>
+  |     raise e
+  |           └ ExceptionGroup('Grouped', [ValueError(1), ValueError(2)])
+  |
+  | ExceptionGroup: Grouped (2 sub-exceptions)
+  | Note 1
+  | Note 2
+  | Note 3
+  +-+---------------- 1 ----------------
+    | ValueError: 1
+    +---------------- 2 ----------------
+    | ValueError: 2
+    +------------------------------------
+
+Traceback (most recent call last):
+  File "tests/exceptions/source/modern/notes.py", line 32, in <module>
+    raise e
+TabError: tab error
+Note
+
+Traceback (most recent call last):
+
+> File "tests/exceptions/source/modern/notes.py", line 32, in <module>
+    raise e
+          └ TabError('tab error')
+
+TabError: tab error
+Note
+
+Traceback (most recent call last):
+  File "tests/exceptions/source/modern/notes.py", line 38, in <module>
+    raise e
+  File "<string>", line 1
+    a = 7 *
+           ^
+SyntaxError: syntax error
+Note 1
+Note 2
+
+Traceback (most recent call last):
+
+> File "tests/exceptions/source/modern/notes.py", line 38, in <module>
+    raise e
+          └ SyntaxError('syntax error', ('<string>', 1, 8, 'a = 7 *\n', 1, 8))
+
+  File "<string>", line 1
+    a = 7 *
+           ^
+
+SyntaxError: syntax error
+Note 1
+Note 2
+
+Traceback (most recent call last):
+  File "tests/exceptions/source/modern/notes.py", line 43, in <module>
+    raise e
+TypeError: type error
+
+Traceback (most recent call last):
+
+> File "tests/exceptions/source/modern/notes.py", line 43, in <module>
+    raise e
+          └ TypeError('type error')
+
+TypeError: type error

tests/exceptions/source/modern/notes.py

@@ -0,0 +1,43 @@
+from loguru import logger
+import sys
+
+
+logger.remove()
+logger.add(sys.stderr, format="", diagnose=False, backtrace=False, colorize=False)
+logger.add(sys.stderr, format="", diagnose=True, backtrace=True, colorize=True)
+
+
+with logger.catch():
+    e = ValueError("invalid value")
+    e.add_note("Note")
+    raise e
+
+
+with logger.catch():
+    e = ValueError("invalid value")
+    e.add_note("Note1")
+    e.add_note("Note2\nNote3\n")
+    raise e
+
+
+with logger.catch():
+    e = ExceptionGroup("Grouped", [ValueError(1), ValueError(2)])
+    e.add_note("Note 1\nNote 2")
+    e.add_note("Note 3")
+    raise e
+
+with logger.catch():
+    e = TabError("tab error")
+    e.add_note("Note")
+    raise e
+
+with logger.catch():
+    e = SyntaxError("syntax error", ("<string>", 1, 8, "a = 7 *\n", 1, 8))
+    e.add_note("Note 1")
+    e.add_note("Note 2")
+    raise e
+
+with logger.catch():
+    e = TypeError("type error")
+    e.__notes__ = None
+    raise e

tests/test_exceptions_formatting.py

@@ -235,6 +235,7 @@ def test_exception_others(filename):
         ("walrus_operator", (3, 8)),
         ("match_statement", (3, 10)),
         ("exception_group_catch", (3, 11)),
+        ("notes", (3, 11)),
         ("grouped_simple", (3, 11)),
         ("grouped_nested", (3, 11)),
         ("grouped_with_cause_and_context", (3, 11)),