gh-128067: Add newline to new REPL output when needed to avoid chopping characters

Lib/_pyrepl/console.py

@@ -24,6 +24,7 @@
 from abc import ABC, abstractmethod
 import ast
 import code
+import io
 from dataclasses import dataclass, field
 import os.path
 import sys
@@ -177,7 +178,19 @@ def _excepthook(self, typ, value, tb):
 
     def runcode(self, code):
         try:
+            temp_output = io.StringIO()
+            old_stdout = sys.stdout
+            sys.stdout = temp_output
             exec(code, self.locals)
+            output = ""
+            if hasattr(sys.stdout, "getvalue"):
+                output = sys.stdout.getvalue()
+                # Avoid restoring old stdout if it has been changed during exec
+                if sys.stdout is temp_output:
+                    sys.stdout = old_stdout
+            if not output.endswith("\n"):
+                output += "\n"
+            print(output, end="")
         except SystemExit:
             raise
         except BaseException:

Lib/test/test_pyrepl/test_pyrepl.py

@@ -1344,6 +1344,16 @@ def test_keyboard_interrupt_after_isearch(self):
         output, exit_code = self.run_repl(["\x12", "\x03", "exit"])
         self.assertEqual(exit_code, 0)
 
+    def test_newline_after_print_ending_in_space(self):
+        commands = ("print('abcdefg' * 250 + 'Z', end=' ')\n"
+                    "exit()\n")
+        output, exit_code = self.run_repl(commands)
+        self.assertEqual(exit_code, 0)
+        print(output)
+        self.assertIn("Z \r\n", output)
+        expected = "abcdefg" * 200 + "Z " + "\r\n"
+        self.assertIn(expected, output)
+
     def test_prompt_after_help(self):
         output, exit_code = self.run_repl(["help", "q", "exit"])