gh-111201: A new Python REPL (GH-111567)

Co-authored-by: Łukasz Langa <lukasz@langa.pl>
Co-authored-by: Marta Gómez Macías <mgmacias@google.com>
Co-authored-by: Lysandros Nikolaou <lisandrosnik@gmail.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

2 files changed, 931 insertions, 2 deletions

diff --git a/Lib/test/test_pyrepl.py b/Lib/test/test_pyrepl.py
new file mode 100644
index 0000000..c53bdef
--- /dev/null
+++ b/Lib/test/test_pyrepl.py
@@ -0,0 +1,929 @@
+import itertools
+import os
+import rlcompleter
+import sys
+import unittest
+from code import InteractiveConsole
+from functools import partial
+from unittest import TestCase
+from unittest.mock import MagicMock, patch
+
+from test.support import requires
+from test.support.import_helper import import_module
+
+# Optionally test pyrepl.  This currently requires that the
+# 'curses' resource be given on the regrtest command line using the -u
+# option.  Additionally, we need to attempt to import curses and readline.
+requires('curses')
+curses = import_module('curses')
+readline = import_module('readline')
+
+from _pyrepl.console import Console, Event
+from _pyrepl.readline import ReadlineAlikeReader, ReadlineConfig
+from _pyrepl.simple_interact import _strip_final_indent
+from _pyrepl.unix_eventqueue import EventQueue
+
+
+def more_lines(unicodetext, namespace=None):
+    if namespace is None:
+        namespace = {}
+    src = _strip_final_indent(unicodetext)
+    console = InteractiveConsole(namespace, filename="<stdin>")
+    try:
+        code = console.compile(src, "<stdin>", "single")
+    except (OverflowError, SyntaxError, ValueError):
+        return False
+    else:
+        return code is None
+
+
+def multiline_input(reader, namespace=None):
+    saved = reader.more_lines
+    try:
+        reader.more_lines = partial(more_lines, namespace=namespace)
+        reader.ps1 = reader.ps2 = ">>>"
+        reader.ps3 = reader.ps4 = "..."
+        return reader.readline()
+    finally:
+        reader.more_lines = saved
+        reader.paste_mode = False
+
+
+def code_to_events(code):
+    for c in code:
+        yield Event(evt="key", data=c, raw=bytearray(c.encode("utf-8")))
+
+
+def prepare_mock_console(events, **kwargs):
+    console = MagicMock()
+    console.get_event.side_effect = events
+    console.height = 100
+    console.width = 80
+    for key, val in kwargs.items():
+        setattr(console, key, val)
+    return console
+
+
+def prepare_fake_console(**kwargs):
+    console = FakeConsole()
+    for key, val in kwargs.items():
+        setattr(console, key, val)
+    return console
+
+
+def prepare_reader(console, **kwargs):
+    config = ReadlineConfig(readline_completer=None)
+    reader = ReadlineAlikeReader(console=console, config=config)
+    reader.more_lines = partial(more_lines, namespace=None)
+    reader.paste_mode = True  # Avoid extra indents
+
+    def get_prompt(lineno, cursor_on_line) -> str:
+        return ""
+
+    reader.get_prompt = get_prompt  # Remove prompt for easier calculations of (x, y)
+
+    for key, val in kwargs.items():
+        setattr(reader, key, val)
+
+    return reader
+
+
+def handle_all_events(
+    events, prepare_console=prepare_mock_console, prepare_reader=prepare_reader
+):
+    console = prepare_console(events)
+    reader = prepare_reader(console)
+    try:
+        while True:
+            reader.handle1()
+    except StopIteration:
+        pass
+    return reader, console
+
+
+handle_events_narrow_console = partial(
+    handle_all_events, prepare_console=partial(prepare_mock_console, width=10)
+)
+
+
+class FakeConsole(Console):
+    def __init__(self, events, encoding="utf-8"):
+        self.events = iter(events)
+        self.encoding = encoding
+        self.screen = []
+        self.height = 100
+        self.width = 80
+
+    def get_event(self, block: bool = True) -> Event | None:
+        return next(self.events)
+
+    def getpending(self) -> Event:
+        return self.get_event(block=False)
+
+    def getheightwidth(self) -> tuple[int, int]:
+        return self.height, self.width
+
+    def refresh(self, screen: list[str], xy: tuple[int, int]) -> None:
+        pass
+
+    def prepare(self) -> None:
+        pass
+
+    def restore(self) -> None:
+        pass
+
+    def move_cursor(self, x: int, y: int) -> None:
+        pass
+
+    def set_cursor_vis(self, visible: bool) -> None:
+        pass
+
+    def push_char(self, char: int | bytes) -> None:
+        pass
+
+    def beep(self) -> None:
+        pass
+
+    def clear(self) -> None:
+        pass
+
+    def finish(self) -> None:
+        pass
+
+    def flushoutput(self) -> None:
+        pass
+
+    def forgetinput(self) -> None:
+        pass
+
+    def wait(self) -> None:
+        pass
+
+    def repaint(self) -> None:
+        pass
+
+
+class TestCursorPosition(TestCase):
+    def test_up_arrow_simple(self):
+        # fmt: off
+        code = (
+            'def f():\n'
+            '  ...\n'
+        )
+        # fmt: on
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+            ],
+        )
+
+        reader, console = handle_all_events(events)
+        self.assertEqual(reader.cxy, (0, 1))
+        console.move_cursor.assert_called_once_with(0, 1)
+
+    def test_down_arrow_end_of_input(self):
+        # fmt: off
+        code = (
+            'def f():\n'
+            '  ...\n'
+        )
+        # fmt: on
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+            ],
+        )
+
+        reader, console = handle_all_events(events)
+        self.assertEqual(reader.cxy, (0, 2))
+        console.move_cursor.assert_called_once_with(0, 2)
+
+    def test_left_arrow_simple(self):
+        events = itertools.chain(
+            code_to_events("11+11"),
+            [
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+            ],
+        )
+
+        reader, console = handle_all_events(events)
+        self.assertEqual(reader.cxy, (4, 0))
+        console.move_cursor.assert_called_once_with(4, 0)
+
+    def test_right_arrow_end_of_line(self):
+        events = itertools.chain(
+            code_to_events("11+11"),
+            [
+                Event(evt="key", data="right", raw=bytearray(b"\x1bOC")),
+            ],
+        )
+
+        reader, console = handle_all_events(events)
+        self.assertEqual(reader.cxy, (5, 0))
+        console.move_cursor.assert_called_once_with(5, 0)
+
+    def test_cursor_position_simple_character(self):
+        events = itertools.chain(code_to_events("k"))
+
+        reader, _ = handle_all_events(events)
+        self.assertEqual(reader.pos, 1)
+
+        # 1 for simple character
+        self.assertEqual(reader.cxy, (1, 0))
+
+    def test_cursor_position_double_width_character(self):
+        events = itertools.chain(code_to_events("樂"))
+
+        reader, _ = handle_all_events(events)
+        self.assertEqual(reader.pos, 1)
+
+        # 2 for wide character
+        self.assertEqual(reader.cxy, (2, 0))
+
+    def test_cursor_position_double_width_character_move_left(self):
+        events = itertools.chain(
+            code_to_events("樂"),
+            [
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+        self.assertEqual(reader.pos, 0)
+        self.assertEqual(reader.cxy, (0, 0))
+
+    def test_cursor_position_double_width_character_move_left_right(self):
+        events = itertools.chain(
+            code_to_events("樂"),
+            [
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+                Event(evt="key", data="right", raw=bytearray(b"\x1bOC")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+        self.assertEqual(reader.pos, 1)
+
+        # 2 for wide character
+        self.assertEqual(reader.cxy, (2, 0))
+
+    def test_cursor_position_double_width_characters_move_up(self):
+        for_loop = "for _ in _:"
+
+        # fmt: off
+        code = (
+           f"{for_loop}\n"
+            "  ' 可口可乐; 可口可樂'"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+
+        # cursor at end of first line
+        self.assertEqual(reader.pos, len(for_loop))
+        self.assertEqual(reader.cxy, (len(for_loop), 0))
+
+    def test_cursor_position_double_width_characters_move_up_down(self):
+        for_loop = "for _ in _:"
+
+        # fmt: off
+        code = (
+           f"{for_loop}\n"
+            "  ' 可口可乐; 可口可樂'"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+
+        # cursor here (showing 2nd line only):
+        # <  ' 可口可乐; 可口可樂'>
+        #              ^
+        self.assertEqual(reader.pos, 19)
+        self.assertEqual(reader.cxy, (10, 1))
+
+    def test_cursor_position_multiple_double_width_characters_move_left(self):
+        events = itertools.chain(
+            code_to_events("' 可口可乐; 可口可樂'"),
+            [
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+                Event(evt="key", data="left", raw=bytearray(b"\x1bOD")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+        self.assertEqual(reader.pos, 10)
+
+        # 1 for quote, 1 for space, 2 per wide character,
+        # 1 for semicolon, 1 for space, 2 per wide character
+        self.assertEqual(reader.cxy, (16, 0))
+
+    def test_cursor_position_move_up_to_eol(self):
+        first_line = "for _ in _:"
+        second_line = "  hello"
+
+        # fmt: off
+        code = (
+            f"{first_line}\n"
+            f"{second_line}\n"
+             "  h\n"
+             "  hel"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+
+        # Cursor should be at end of line 1, even though line 2 is shorter
+        # for _ in _:
+        #   hello
+        #   h
+        #   hel
+        self.assertEqual(
+            reader.pos, len(first_line) + len(second_line) + 1
+        )  # +1 for newline
+        self.assertEqual(reader.cxy, (len(second_line), 1))
+
+    def test_cursor_position_move_down_to_eol(self):
+        last_line = "  hel"
+
+        # fmt: off
+        code = (
+            "for _ in _:\n"
+            "  hello\n"
+            "  h\n"
+           f"{last_line}"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+            ],
+        )
+
+        reader, _ = handle_all_events(events)
+
+        # Cursor should be at end of line 3, even though line 2 is shorter
+        # for _ in _:
+        #   hello
+        #   h
+        #   hel
+        self.assertEqual(reader.pos, len(code))
+        self.assertEqual(reader.cxy, (len(last_line), 3))
+
+    def test_cursor_position_multiple_mixed_lines_move_up(self):
+        # fmt: off
+        code = (
+            "def foo():\n"
+            "  x = '可口可乐; 可口可樂'\n"
+            "  y = 'abckdfjskldfjslkdjf'"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            13 * [Event(evt="key", data="left", raw=bytearray(b"\x1bOD"))],
+            [Event(evt="key", data="up", raw=bytearray(b"\x1bOA"))],
+        )
+
+        reader, _ = handle_all_events(events)
+
+        # By moving left, we're before the s:
+        # y = 'abckdfjskldfjslkdjf'
+        #             ^
+        # And we should move before the semi-colon despite the different offset
+        # x = '可口可乐; 可口可樂'
+        #            ^
+        self.assertEqual(reader.pos, 22)
+        self.assertEqual(reader.cxy, (15, 1))
+
+    def test_cursor_position_after_wrap_and_move_up(self):
+        # fmt: off
+        code = (
+            "def foo():\n"
+            "  hello"
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            code_to_events(code),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+            ],
+        )
+        reader, _ = handle_events_narrow_console(events)
+
+        # The code looks like this:
+        # def foo()\
+        # :
+        #   hello
+        # After moving up we should be after the colon in line 2
+        self.assertEqual(reader.pos, 10)
+        self.assertEqual(reader.cxy, (1, 1))
+
+
+class TestPyReplOutput(TestCase):
+    def prepare_reader(self, events):
+        console = FakeConsole(events)
+        config = ReadlineConfig(readline_completer=None)
+        reader = ReadlineAlikeReader(console=console, config=config)
+        return reader
+
+    def test_basic(self):
+        reader = self.prepare_reader(code_to_events("1+1\n"))
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+
+    def test_multiline_edit(self):
+        events = itertools.chain(
+            code_to_events("def f():\n  ...\n\n"),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="right", raw=bytearray(b"\x1bOC")),
+                Event(evt="key", data="right", raw=bytearray(b"\x1bOC")),
+                Event(evt="key", data="right", raw=bytearray(b"\x1bOC")),
+                Event(evt="key", data="backspace", raw=bytearray(b"\x7f")),
+                Event(evt="key", data="g", raw=bytearray(b"g")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ],
+        )
+        reader = self.prepare_reader(events)
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "def f():\n  ...\n  ")
+        output = multiline_input(reader)
+        self.assertEqual(output, "def g():\n  ...\n  ")
+
+    def test_history_navigation_with_up_arrow(self):
+        events = itertools.chain(
+            code_to_events("1+1\n2+2\n"),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ],
+        )
+
+        reader = self.prepare_reader(events)
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+        output = multiline_input(reader)
+        self.assertEqual(output, "2+2")
+        output = multiline_input(reader)
+        self.assertEqual(output, "2+2")
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+
+    def test_history_navigation_with_down_arrow(self):
+        events = itertools.chain(
+            code_to_events("1+1\n2+2\n"),
+            [
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="up", raw=bytearray(b"\x1bOA")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+                Event(evt="key", data="down", raw=bytearray(b"\x1bOB")),
+            ],
+        )
+
+        reader = self.prepare_reader(events)
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+
+    def test_history_search(self):
+        events = itertools.chain(
+            code_to_events("1+1\n2+2\n3+3\n"),
+            [
+                Event(evt="key", data="\x12", raw=bytearray(b"\x12")),
+                Event(evt="key", data="1", raw=bytearray(b"1")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+                Event(evt="key", data="\n", raw=bytearray(b"\n")),
+            ],
+        )
+
+        reader = self.prepare_reader(events)
+
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+        output = multiline_input(reader)
+        self.assertEqual(output, "2+2")
+        output = multiline_input(reader)
+        self.assertEqual(output, "3+3")
+        output = multiline_input(reader)
+        self.assertEqual(output, "1+1")
+
+    def test_control_character(self):
+        events = code_to_events("c\x1d\n")
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, "c\x1d")
+
+
+class TestPyReplCompleter(TestCase):
+    def prepare_reader(self, events, namespace):
+        console = FakeConsole(events)
+        config = ReadlineConfig()
+        config.readline_completer = rlcompleter.Completer(namespace).complete
+        reader = ReadlineAlikeReader(console=console, config=config)
+        return reader
+
+    def test_simple_completion(self):
+        events = code_to_events("os.geten\t\n")
+
+        namespace = {"os": os}
+        reader = self.prepare_reader(events, namespace)
+
+        output = multiline_input(reader, namespace)
+        self.assertEqual(output, "os.getenv")
+
+    def test_completion_with_many_options(self):
+        events = code_to_events("os.\t\tO_AS\t\n")
+
+        namespace = {"os": os}
+        reader = self.prepare_reader(events, namespace)
+
+        output = multiline_input(reader, namespace)
+        self.assertEqual(output, "os.O_ASYNC")
+
+    def test_empty_namespace_completion(self):
+        events = code_to_events("os.geten\t\n")
+        namespace = {}
+        reader = self.prepare_reader(events, namespace)
+
+        output = multiline_input(reader, namespace)
+        self.assertEqual(output, "os.geten")
+
+    def test_global_namespace_completion(self):
+        events = code_to_events("py\t\n")
+        namespace = {"python": None}
+        reader = self.prepare_reader(events, namespace)
+        output = multiline_input(reader, namespace)
+        self.assertEqual(output, "python")
+
+
+@patch("_pyrepl.curses.tigetstr", lambda x: b"")
+class TestUnivEventQueue(TestCase):
+    def test_get(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        event = Event("key", "a", b"a")
+        eq.insert(event)
+        self.assertEqual(eq.get(), event)
+
+    def test_empty(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        self.assertTrue(eq.empty())
+        eq.insert(Event("key", "a", b"a"))
+        self.assertFalse(eq.empty())
+
+    def test_flush_buf(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.buf.extend(b"test")
+        self.assertEqual(eq.flush_buf(), b"test")
+        self.assertEqual(eq.buf, bytearray())
+
+    def test_insert(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        event = Event("key", "a", b"a")
+        eq.insert(event)
+        self.assertEqual(eq.events[0], event)
+
+    @patch("_pyrepl.unix_eventqueue.keymap")
+    def test_push_with_key_in_keymap(self, mock_keymap):
+        mock_keymap.compile_keymap.return_value = {"a": "b"}
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {b"a": "b"}
+        eq.push("a")
+        self.assertTrue(mock_keymap.compile_keymap.called)
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "b")
+
+    @patch("_pyrepl.unix_eventqueue.keymap")
+    def test_push_without_key_in_keymap(self, mock_keymap):
+        mock_keymap.compile_keymap.return_value = {"a": "b"}
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {b"c": "d"}
+        eq.push("a")
+        self.assertTrue(mock_keymap.compile_keymap.called)
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "a")
+
+    @patch("_pyrepl.unix_eventqueue.keymap")
+    def test_push_with_keymap_in_keymap(self, mock_keymap):
+        mock_keymap.compile_keymap.return_value = {"a": "b"}
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {b"a": {b"b": "c"}}
+        eq.push("a")
+        self.assertTrue(mock_keymap.compile_keymap.called)
+        self.assertTrue(eq.empty())
+        eq.push("b")
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "c")
+        eq.push("d")
+        self.assertEqual(eq.events[1].evt, "key")
+        self.assertEqual(eq.events[1].data, "d")
+
+    @patch("_pyrepl.unix_eventqueue.keymap")
+    def test_push_with_keymap_in_keymap_and_escape(self, mock_keymap):
+        mock_keymap.compile_keymap.return_value = {"a": "b"}
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {b"a": {b"b": "c"}}
+        eq.push("a")
+        self.assertTrue(mock_keymap.compile_keymap.called)
+        self.assertTrue(eq.empty())
+        eq.flush_buf()
+        eq.push("\033")
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "\033")
+        eq.push("b")
+        self.assertEqual(eq.events[1].evt, "key")
+        self.assertEqual(eq.events[1].data, "b")
+
+    def test_push_special_key(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {}
+        eq.push("\x1b")
+        eq.push("[")
+        eq.push("A")
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "\x1b")
+
+    def test_push_unrecognized_escape_sequence(self):
+        eq = EventQueue(sys.stdout.fileno(), "utf-8")
+        eq.keymap = {}
+        eq.push("\x1b")
+        eq.push("[")
+        eq.push("Z")
+        self.assertEqual(len(eq.events), 3)
+        self.assertEqual(eq.events[0].evt, "key")
+        self.assertEqual(eq.events[0].data, "\x1b")
+        self.assertEqual(eq.events[1].evt, "key")
+        self.assertEqual(eq.events[1].data, "[")
+        self.assertEqual(eq.events[2].evt, "key")
+        self.assertEqual(eq.events[2].data, "Z")
+
+
+class TestPasteEvent(TestCase):
+    def prepare_reader(self, events):
+        console = FakeConsole(events)
+        config = ReadlineConfig(readline_completer=None)
+        reader = ReadlineAlikeReader(console=console, config=config)
+        return reader
+
+    def test_paste(self):
+        # fmt: off
+        code = (
+            'def a():\n'
+            '  for x in range(10):\n'
+            '    if x%2:\n'
+            '      print(x)\n'
+            '    else:\n'
+            '      pass\n'
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            [
+                Event(evt="key", data="f3", raw=bytearray(b"\x1bOR")),
+            ],
+            code_to_events(code),
+            [
+                Event(evt="key", data="f3", raw=bytearray(b"\x1bOR")),
+            ],
+            code_to_events("\n"),
+        )
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, code)
+
+    def test_paste_mid_newlines(self):
+        # fmt: off
+        code = (
+            'def f():\n'
+            '  x = y\n'
+            '  \n'
+            '  y = z\n'
+        )
+        # fmt: on
+
+        events = itertools.chain(
+            [
+                Event(evt="key", data="f3", raw=bytearray(b"\x1bOR")),
+            ],
+            code_to_events(code),
+            [
+                Event(evt="key", data="f3", raw=bytearray(b"\x1bOR")),
+            ],
+            code_to_events("\n"),
+        )
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, code)
+
+    def test_paste_mid_newlines_not_in_paste_mode(self):
+        # fmt: off
+        code = (
+            'def f():\n'
+            '  x = y\n'
+            '  \n'
+            '  y = z\n\n'
+        )
+
+        expected = (
+            'def f():\n'
+            '  x = y\n'
+            '    '
+        )
+        # fmt: on
+
+        events = code_to_events(code)
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, expected)
+
+    def test_paste_not_in_paste_mode(self):
+        # fmt: off
+        input_code = (
+            'def a():\n'
+            '  for x in range(10):\n'
+            '    if x%2:\n'
+            '      print(x)\n'
+            '    else:\n'
+            '      pass\n\n'
+        )
+
+        output_code = (
+            'def a():\n'
+            '  for x in range(10):\n'
+            '      if x%2:\n'
+            '            print(x)\n'
+            '                else:'
+        )
+        # fmt: on
+
+        events = code_to_events(input_code)
+        reader = self.prepare_reader(events)
+        output = multiline_input(reader)
+        self.assertEqual(output, output_code)
+
+
+class TestReader(TestCase):
+    def assert_screen_equals(self, reader, expected):
+        actual = reader.calc_screen()
+        expected = expected.split("\n")
+        self.assertListEqual(actual, expected)
+
+    def test_calc_screen_wrap_simple(self):
+        events = code_to_events(10 * "a")
+        reader, _ = handle_events_narrow_console(events)
+        self.assert_screen_equals(reader, f"{9*"a"}\\\na")
+
+    def test_calc_screen_wrap_wide_characters(self):
+        events = code_to_events(8 * "a" + "樂")
+        reader, _ = handle_events_narrow_console(events)
+        self.assert_screen_equals(reader, f"{8*"a"}\\\n樂")
+
+    def test_calc_screen_wrap_three_lines(self):
+        events = code_to_events(20 * "a")
+        reader, _ = handle_events_narrow_console(events)
+        self.assert_screen_equals(reader, f"{9*"a"}\\\n{9*"a"}\\\naa")
+
+    def test_calc_screen_wrap_three_lines_mixed_character(self):
+        # fmt: off
+        code = (
+            "def f():\n"
+           f"  {8*"a"}\n"
+           f"  {5*"樂"}"
+        )
+        # fmt: on
+
+        events = code_to_events(code)
+        reader, _ = handle_events_narrow_console(events)
+
+        # fmt: off
+        self.assert_screen_equals(reader, (
+            "def f():\n"
+           f"  {7*"a"}\\\n"
+            "a\n"
+           f"  {3*"樂"}\\\n"
+            "樂樂"
+        ))
+        # fmt: on
+
+    def test_calc_screen_backspace(self):
+        events = itertools.chain(
+            code_to_events("aaa"),
+            [
+                Event(evt="key", data="backspace", raw=bytearray(b"\x7f")),
+            ],
+        )
+        reader, _ = handle_all_events(events)
+        self.assert_screen_equals(reader, "aa")
+
+    def test_calc_screen_wrap_removes_after_backspace(self):
+        events = itertools.chain(
+            code_to_events(10 * "a"),
+            [
+                Event(evt="key", data="backspace", raw=bytearray(b"\x7f")),
+            ],
+        )
+        reader, _ = handle_events_narrow_console(events)
+        self.assert_screen_equals(reader, 9 * "a")
+
+    def test_calc_screen_backspace_in_second_line_after_wrap(self):
+        events = itertools.chain(
+            code_to_events(11 * "a"),
+            [
+                Event(evt="key", data="backspace", raw=bytearray(b"\x7f")),
+            ],
+        )
+        reader, _ = handle_events_narrow_console(events)
+        self.assert_screen_equals(reader, f"{9*"a"}\\\na")
+
+    def test_setpos_for_xy_simple(self):
+        events = code_to_events("11+11")
+        reader, _ = handle_all_events(events)
+        reader.setpos_from_xy(0, 0)
+        self.assertEqual(reader.pos, 0)
+
+    def test_setpos_from_xy_multiple_lines(self):
+        # fmt: off
+        code = (
+            "def foo():\n"
+            "  return 1"
+        )
+        # fmt: on
+
+        events = code_to_events(code)
+        reader, _ = handle_all_events(events)
+        reader.setpos_from_xy(2, 1)
+        self.assertEqual(reader.pos, 13)
+
+    def test_setpos_from_xy_after_wrap(self):
+        # fmt: off
+        code = (
+            "def foo():\n"
+            "  hello"
+        )
+        # fmt: on
+
+        events = code_to_events(code)
+        reader, _ = handle_events_narrow_console(events)
+        reader.setpos_from_xy(2, 2)
+        self.assertEqual(reader.pos, 13)
+
+    def test_setpos_fromxy_in_wrapped_line(self):
+        # fmt: off
+        code = (
+            "def foo():\n"
+            "  hello"
+        )
+        # fmt: on
+
+        events = code_to_events(code)
+        reader, _ = handle_events_narrow_console(events)
+        reader.setpos_from_xy(0, 1)
+        self.assertEqual(reader.pos, 9)
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Lib/test/test_traceback.py b/Lib/test/test_traceback.py
index 8969e01..7e48510 100644
--- a/Lib/test/test_traceback.py
+++ b/Lib/test/test_traceback.py
@@ -500,7 +500,7 @@ class TracebackCases(unittest.TestCase):
             traceback.format_exception(e.__class__, e)
         with self.assertRaisesRegex(ValueError, 'Both or neither'):
             traceback.format_exception(e.__class__, tb=e.__traceback__)
-        with self.assertRaisesRegex(TypeError, 'positional-only'):
+        with self.assertRaisesRegex(TypeError, 'required positional argument'):
             traceback.format_exception(exc=e)
 
     def test_format_exception_only_exc(self):
@@ -539,7 +539,7 @@ class TracebackCases(unittest.TestCase):
         self.assertEqual(
             str(inspect.signature(traceback.format_exception)),
             ('(exc, /, value=<implicit>, tb=<implicit>, limit=None, '
-             'chain=True)'))
+             'chain=True, **kwargs)'))
 
         self.assertEqual(
             str(inspect.signature(traceback.format_exception_only)),