Mock session to avoid Windows issues on CI.

Instantiating a real session on Windows CI leads to exception:

```
prompt_toolkit.output.win32.NoConsoleScreenBufferError: No Windows console found. Are you running cmd.exe?
```

with the following traceback:

```
IPython\terminal\tests\test_shortcuts.py:214:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\shortcuts\prompt.py:476: in __init__
    self.app = self._create_application(editing_mode, erase_when_done)
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\shortcuts\prompt.py:765: in _create_application
    output=self._output,
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\application\application.py:282: in __init__
    self.output = output or session.output
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\application\current.py:71: in output
    self._output = create_output()
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\output\defaults.py:85: in create_output
    return Win32Output(stdout, default_color_depth=color_depth_from_env)
C:\hostedtoolcache\windows\PyPy\3.8.15\x86\lib\site-packages\prompt_toolkit\output\win32.py:114: in __init__
    info = self.get_win32_screen_buffer_info()
```

IPython/terminal/tests/test_shortcuts.py

@@ -1,233 +1,238 b''
 import pytest
 from IPython.terminal.shortcuts.auto_suggest import (
     accept_in_vi_insert_mode,
     accept_token,
     accept_character,
     accept_word,
     accept_and_keep_cursor,
     NavigableAutoSuggestFromHistory,
     swap_autosuggestion_up,
     swap_autosuggestion_down,
 )
 
 from prompt_toolkit.history import InMemoryHistory
-from prompt_toolkit.shortcuts import PromptSession
 from prompt_toolkit.buffer import Buffer
 
 from unittest.mock import patch, Mock
 
 
 def make_event(text, cursor, suggestion):
     event = Mock()
     event.current_buffer = Mock()
     event.current_buffer.suggestion = Mock()
     event.current_buffer.text = text
     event.current_buffer.cursor_position = cursor
     event.current_buffer.suggestion.text = suggestion
     event.current_buffer.document = Mock()
     event.current_buffer.document.get_end_of_line_position = Mock(return_value=0)
     event.current_buffer.document.text = text
     event.current_buffer.document.cursor_position = cursor
     return event
 
 
 @pytest.mark.parametrize(
     "text, cursor, suggestion, called",
     [
         ("123456", 6, "123456789", True),
         ("123456", 3, "123456789", False),
         ("123456   \n789", 6, "123456789", True),
     ],
 )
 def test_autosuggest_at_EOL(text, cursor, suggestion, called):
     """
     test that autosuggest is only applied at end of line.
     """
 
     event = make_event(text, cursor, suggestion)
     event.current_buffer.insert_text = Mock()
     accept_in_vi_insert_mode(event)
     if called:
         event.current_buffer.insert_text.assert_called()
     else:
         event.current_buffer.insert_text.assert_not_called()
         # event.current_buffer.document.get_end_of_line_position.assert_called()
 
 
 @pytest.mark.parametrize(
     "text, suggestion, expected",
     [
         ("", "def out(tag: str, n=50):", "def "),
         ("d", "ef out(tag: str, n=50):", "ef "),
         ("de ", "f out(tag: str, n=50):", "f "),
         ("def", " out(tag: str, n=50):", " "),
         ("def ", "out(tag: str, n=50):", "out("),
         ("def o", "ut(tag: str, n=50):", "ut("),
         ("def ou", "t(tag: str, n=50):", "t("),
         ("def out", "(tag: str, n=50):", "("),
         ("def out(", "tag: str, n=50):", "tag: "),
         ("def out(t", "ag: str, n=50):", "ag: "),
         ("def out(ta", "g: str, n=50):", "g: "),
         ("def out(tag", ": str, n=50):", ": "),
         ("def out(tag:", " str, n=50):", " "),
         ("def out(tag: ", "str, n=50):", "str, "),
         ("def out(tag: s", "tr, n=50):", "tr, "),
         ("def out(tag: st", "r, n=50):", "r, "),
         ("def out(tag: str", ", n=50):", ", n"),
         ("def out(tag: str,", " n=50):", " n"),
         ("def out(tag: str, ", "n=50):", "n="),
         ("def out(tag: str, n", "=50):", "="),
         ("def out(tag: str, n=", "50):", "50)"),
         ("def out(tag: str, n=5", "0):", "0)"),
         ("def out(tag: str, n=50", "):", "):"),
         ("def out(tag: str, n=50)", ":", ":"),
     ],
 )
 def test_autosuggest_token(text, suggestion, expected):
     event = make_event(text, len(text), suggestion)
     event.current_buffer.insert_text = Mock()
     accept_token(event)
     assert event.current_buffer.insert_text.called
     assert event.current_buffer.insert_text.call_args[0] == (expected,)
 
 
 @pytest.mark.parametrize(
     "text, suggestion, expected",
     [
         ("", "def out(tag: str, n=50):", "d"),
         ("d", "ef out(tag: str, n=50):", "e"),
         ("de ", "f out(tag: str, n=50):", "f"),
         ("def", " out(tag: str, n=50):", " "),
     ],
 )
 def test_accept_character(text, suggestion, expected):
     event = make_event(text, len(text), suggestion)
     event.current_buffer.insert_text = Mock()
     accept_character(event)
     assert event.current_buffer.insert_text.called
     assert event.current_buffer.insert_text.call_args[0] == (expected,)
 
 
 @pytest.mark.parametrize(
     "text, suggestion, expected",
     [
         ("", "def out(tag: str, n=50):", "def "),
         ("d", "ef out(tag: str, n=50):", "ef "),
         ("de", "f out(tag: str, n=50):", "f "),
         ("def", " out(tag: str, n=50):", " "),
         # (this is why we also have accept_token)
         ("def ", "out(tag: str, n=50):", "out(tag: "),
     ],
 )
 def test_accept_word(text, suggestion, expected):
     event = make_event(text, len(text), suggestion)
     event.current_buffer.insert_text = Mock()
     accept_word(event)
     assert event.current_buffer.insert_text.called
     assert event.current_buffer.insert_text.call_args[0] == (expected,)
 
 
 @pytest.mark.parametrize(
     "text, suggestion, expected, cursor",
     [
         ("", "def out(tag: str, n=50):", "def out(tag: str, n=50):", 0),
         ("def ", "out(tag: str, n=50):", "out(tag: str, n=50):", 4),
     ],
 )
 def test_accept_and_keep_cursor(text, suggestion, expected, cursor):
     event = make_event(text, cursor, suggestion)
     buffer = event.current_buffer
     buffer.insert_text = Mock()
     accept_and_keep_cursor(event)
     assert buffer.insert_text.called
     assert buffer.insert_text.call_args[0] == (expected,)
     assert buffer.cursor_position == cursor
 
 
 def test_autosuggest_token_empty():
     full = "def out(tag: str, n=50):"
     event = make_event(full, len(full), "")
     event.current_buffer.insert_text = Mock()
 
     with patch(
         "prompt_toolkit.key_binding.bindings.named_commands.forward_word"
     ) as forward_word:
         accept_token(event)
         assert not event.current_buffer.insert_text.called
         assert forward_word.called
 
 
 async def test_navigable_provider():
     provider = NavigableAutoSuggestFromHistory()
     history = InMemoryHistory(history_strings=["very_a", "very", "very_b", "very_c"])
     buffer = Buffer(history=history)
 
     async for _ in history.load():
         pass
 
     buffer.cursor_position = 5
     buffer.text = "very"
 
     up = swap_autosuggestion_up(provider)
     down = swap_autosuggestion_down(provider)
 
     event = Mock()
     event.current_buffer = buffer
 
     def get_suggestion():
         suggestion = provider.get_suggestion(buffer, buffer.document)
         buffer.suggestion = suggestion
         return suggestion
 
     assert get_suggestion().text == "_c"
 
     # should go up
     up(event)
     assert get_suggestion().text == "_b"
 
     # should skip over 'very' which is identical to buffer content
     up(event)
     assert get_suggestion().text == "_a"
 
     # should cycle back to beginning
     up(event)
     assert get_suggestion().text == "_c"
 
     # should cycle back through end boundary
     down(event)
     assert get_suggestion().text == "_a"
 
     down(event)
     assert get_suggestion().text == "_b"
 
     down(event)
     assert get_suggestion().text == "_c"
 
     down(event)
     assert get_suggestion().text == "_a"
 
 
+def create_session_mock():
+    session = Mock()
+    session.default_buffer = Buffer()
+    return session
+
+
 def test_navigable_provider_connection():
     provider = NavigableAutoSuggestFromHistory()
     provider.skip_lines = 1
 
-    session_1 = PromptSession()
+    session_1 = create_session_mock()
     provider.connect(session_1)
 
     assert provider.skip_lines == 1
     session_1.default_buffer.on_text_insert.fire()
     assert provider.skip_lines == 0
 
-    session_2 = PromptSession()
+    session_2 = create_session_mock()
     provider.connect(session_2)
     provider.skip_lines = 2
 
     assert provider.skip_lines == 2
     session_2.default_buffer.on_text_insert.fire()
     assert provider.skip_lines == 0
 
     provider.skip_lines = 3
     provider.disconnect()
     session_1.default_buffer.on_text_insert.fire()
     session_2.default_buffer.on_text_insert.fire()
     assert provider.skip_lines == 3