gh-135511 Fixed NameError and AttributeError lack of the message in IDLE

Lib/idlelib/idle_test/test_run.py

@@ -45,14 +45,18 @@ def __eq__(self, other):
             ('int.reel', AttributeError,
                  "type object 'int' has no attribute 'reel'. "
                  "Did you mean: 'real'?\n"),
+            (r'raise NameError("123\n456")', NameError, "123\n456\n"),
             )
 
     @force_not_colorized
     def test_get_message(self):
         for code, exc, msg in self.data:
             with self.subTest(code=code):
                 try:
-                    eval(compile(code, '', 'eval'))
+                    if "raise" not in code:
+                        eval(compile(code, '', 'eval'))
+                    else:
+                        exec(compile(code, '', 'exec')) # code r"raise NameError("123\n456")" cannot run in "eval" mode: SyntaxError
                 except exc:
                     typ, val, tb = sys.exc_info()
                     actual = run.get_message_lines(typ, val, tb)[0]
@@ -64,15 +68,26 @@ def test_get_message(self):
                        new_callable=lambda: (lambda t, e: None))
     def test_get_multiple_message(self, mock):
         d = self.data
-        data2 = ((d[0], d[1]), (d[1], d[2]), (d[2], d[0]))
+        data2 = ((d[0], d[1]),
+                 (d[1], d[2]),
+                 (d[2], d[3]),
+                 (d[3], d[0]),
+                 (d[1], d[3]),
+                 (d[0], d[2]))
         subtests = 0
         for (code1, exc1, msg1), (code2, exc2, msg2) in data2:
             with self.subTest(codes=(code1,code2)):
                 try:
-                    eval(compile(code1, '', 'eval'))
+                    if "raise" not in code1:
+                        eval(compile(code1, '', 'eval'))
+                    else:
+                        exec(compile(code1, '', 'exec'))
                 except exc1:
                     try:
-                        eval(compile(code2, '', 'eval'))
+                        if "raise" not in code2:
+                            eval(compile(code2, '', 'eval'))
+                        else:
+                            exec(compile(code2, '', 'exec'))
                     except exc2:
                         with captured_stderr() as output:
                             run.print_exception()

Lib/idlelib/run.py

@@ -235,7 +235,15 @@ def get_message_lines(typ, exc, tb):
         err = io.StringIO()
         with contextlib.redirect_stderr(err):
             sys.__excepthook__(typ, exc, tb)
-        return [err.getvalue().split("\n")[-2] + "\n"]
+        err_list = err.getvalue().split("\n")[1:]
+
+        for i in range(len(err_list)):
+            if err_list[i].startswith(" "):
+                continue
+            else:
+                err_list = err_list[i:-1]
+                break
+        return ["\n".join(err_list) + "\n"]
     else:
         return traceback.format_exception_only(typ, exc)
 

Misc/NEWS.d/next/IDLE/2025-08-08-10-50-59.gh-issue-135511.9Rw5Zg.rst

@@ -0,0 +1,2 @@
+Fix the missing error message in "NameError" and "AttributeError" in IDLE
+when "\n" in message