Add an option to disable no-op completion filtering

src/prompt_toolkit/buffer.py

@@ -197,6 +197,8 @@ class Buffer:
     :param complete_while_typing: :class:`~prompt_toolkit.filters.Filter`
         or `bool`. Decide whether or not to do asynchronous autocompleting while
         typing.
+    :param filter_noop_completions: :class:`~prompt_toolkit.filters.Filter` or
+        `bool`. Ignore a single completion that would not change the input.
     :param validate_while_typing: :class:`~prompt_toolkit.filters.Filter`
         or `bool`. Decide whether or not to do asynchronous validation while
         typing.
@@ -235,10 +237,12 @@ def __init__(
         on_cursor_position_changed: BufferEventHandler | None = None,
         on_completions_changed: BufferEventHandler | None = None,
         on_suggestion_set: BufferEventHandler | None = None,
+        filter_noop_completions: FilterOrBool = True,
     ) -> None:
         # Accept both filters and booleans as input.
         enable_history_search = to_filter(enable_history_search)
         complete_while_typing = to_filter(complete_while_typing)
+        filter_noop_completions = to_filter(filter_noop_completions)
         validate_while_typing = to_filter(validate_while_typing)
         read_only = to_filter(read_only)
         multiline = to_filter(multiline)
@@ -253,6 +257,7 @@ def __init__(
 
         # Filters. (Usually, used by the key bindings to drive the buffer.)
         self.complete_while_typing = complete_while_typing
+        self.filter_noop_completions = filter_noop_completions
         self.validate_while_typing = validate_while_typing
         self.enable_history_search = enable_history_search
         self.read_only = read_only
@@ -1761,8 +1766,10 @@ async def refresh_while_loading() -> None:
             completions = complete_state.completions
 
             # When there is only one completion, which has nothing to add, ignore it.
-            if len(completions) == 1 and completion_does_nothing(
-                document, completions[0]
+            if (
+                self.filter_noop_completions()
+                and len(completions) == 1
+                and completion_does_nothing(document, completions[0])
             ):
                 del completions[:]
 

src/prompt_toolkit/shortcuts/prompt.py

@@ -256,6 +256,9 @@ class PromptSession(Generic[_T]):
     :param complete_while_typing: `bool` or
         :class:`~prompt_toolkit.filters.Filter`. Enable autocompletion while
         typing.
+    :param filter_noop_completions: `bool` or
+        :class:`~prompt_toolkit.filters.Filter`. Ignore a single completion
+        that would not change the input.
     :param validate_while_typing: `bool` or
         :class:`~prompt_toolkit.filters.Filter`. Enable input validation while
         typing.
@@ -358,6 +361,7 @@ class PromptSession(Generic[_T]):
         "enable_history_search",
         "search_ignore_case",
         "complete_while_typing",
+        "filter_noop_completions",
         "validate_while_typing",
         "complete_style",
         "mouse_support",
@@ -386,6 +390,7 @@ def __init__(
         vi_mode: bool = False,
         editing_mode: EditingMode = EditingMode.EMACS,
         complete_while_typing: FilterOrBool = True,
+        filter_noop_completions: FilterOrBool = True,
         validate_while_typing: FilterOrBool = True,
         enable_history_search: FilterOrBool = False,
         search_ignore_case: FilterOrBool = False,
@@ -457,6 +462,7 @@ def __init__(
         self.enable_history_search = enable_history_search
         self.search_ignore_case = search_ignore_case
         self.complete_while_typing = complete_while_typing
+        self.filter_noop_completions = filter_noop_completions
         self.validate_while_typing = validate_while_typing
         self.complete_style = complete_style
         self.mouse_support = mouse_support
@@ -527,6 +533,7 @@ def accept(buff: Buffer) -> bool:
                     and not self.complete_style == CompleteStyle.READLINE_LIKE
                 )
             ),
+            filter_noop_completions=dyncond("filter_noop_completions"),
             validate_while_typing=dyncond("validate_while_typing"),
             enable_history_search=dyncond("enable_history_search"),
             validator=DynamicValidator(lambda: self.validator),
@@ -907,6 +914,7 @@ def prompt(
         enable_history_search: FilterOrBool | None = None,
         search_ignore_case: FilterOrBool | None = None,
         complete_while_typing: FilterOrBool | None = None,
+        filter_noop_completions: FilterOrBool | None = None,
         validate_while_typing: FilterOrBool | None = None,
         complete_style: CompleteStyle | None = None,
         auto_suggest: AutoSuggest | None = None,
@@ -1018,6 +1026,8 @@ class itself. For these, passing in ``None`` will keep the current
             self.search_ignore_case = search_ignore_case
         if complete_while_typing is not None:
             self.complete_while_typing = complete_while_typing
+        if filter_noop_completions is not None:
+            self.filter_noop_completions = filter_noop_completions
         if validate_while_typing is not None:
             self.validate_while_typing = validate_while_typing
         if complete_style is not None:
@@ -1147,6 +1157,7 @@ async def prompt_async(
         enable_history_search: FilterOrBool | None = None,
         search_ignore_case: FilterOrBool | None = None,
         complete_while_typing: FilterOrBool | None = None,
+        filter_noop_completions: FilterOrBool | None = None,
         validate_while_typing: FilterOrBool | None = None,
         complete_style: CompleteStyle | None = None,
         auto_suggest: AutoSuggest | None = None,
@@ -1215,6 +1226,8 @@ async def prompt_async(
             self.search_ignore_case = search_ignore_case
         if complete_while_typing is not None:
             self.complete_while_typing = complete_while_typing
+        if filter_noop_completions is not None:
+            self.filter_noop_completions = filter_noop_completions
         if validate_while_typing is not None:
             self.validate_while_typing = validate_while_typing
         if complete_style is not None:
@@ -1423,6 +1436,7 @@ def prompt(
     enable_history_search: FilterOrBool | None = None,
     search_ignore_case: FilterOrBool | None = None,
     complete_while_typing: FilterOrBool | None = None,
+    filter_noop_completions: FilterOrBool | None = None,
     validate_while_typing: FilterOrBool | None = None,
     complete_style: CompleteStyle | None = None,
     auto_suggest: AutoSuggest | None = None,
@@ -1479,6 +1493,7 @@ def prompt(
         enable_history_search=enable_history_search,
         search_ignore_case=search_ignore_case,
         complete_while_typing=complete_while_typing,
+        filter_noop_completions=filter_noop_completions,
         validate_while_typing=validate_while_typing,
         complete_style=complete_style,
         auto_suggest=auto_suggest,

tests/test_buffer.py

@@ -1,8 +1,14 @@
 from __future__ import annotations
 
+import asyncio
+
 import pytest
 
 from prompt_toolkit.buffer import Buffer
+from prompt_toolkit.completion import WordCompleter
+from prompt_toolkit.input import DummyInput
+from prompt_toolkit.output import DummyOutput
+from prompt_toolkit.shortcuts import PromptSession
 
 
 @pytest.fixture
@@ -16,6 +22,31 @@ def test_initial(_buffer):
     assert _buffer.cursor_position == 0
 
 
+@pytest.mark.parametrize(
+    ("filter_noop_completions", "has_completions"),
+    [(True, False), (False, True)],
+)
+def test_filter_noop_completions(filter_noop_completions, has_completions):
+    buffer = Buffer(
+        completer=WordCompleter(["show"]),
+        filter_noop_completions=filter_noop_completions,
+    )
+    buffer.text = "show"
+    buffer.cursor_position = len(buffer.text)
+
+    asyncio.run(buffer._create_completer_coroutine()())
+
+    assert (buffer.complete_state is not None) is has_completions
+
+
+def test_prompt_session_filter_noop_completions():
+    session = PromptSession(
+        input=DummyInput(), output=DummyOutput(), filter_noop_completions=False
+    )
+
+    assert not session.default_buffer.filter_noop_completions()
+
+
 def test_insert_text(_buffer):
     _buffer.insert_text("some_text")
     assert _buffer.text == "some_text"