Bug fix in ControlX-ControlX binding + unit test.

The cursor did not go to the start of the line when we were at the
latest line of a multi-line input, or in a single line input.

Author: jonathanslenders

prompt_toolkit/key_binding/bindings/emacs.py

@@ -198,7 +198,7 @@ def _(event):
         """
         buffer = event.current_buffer
 
-        if buffer.document.current_char == '\n':
+        if buffer.document.is_cursor_at_the_end_of_line:
             buffer.cursor_position += buffer.document.get_start_of_line_position(after_whitespace=False)
         else:
             buffer.cursor_position += buffer.document.get_end_of_line_position()

tests/test_cli.py

@@ -245,6 +245,21 @@ def test_emacs_other_bindings():
     assert result.text == 'hello X'
 
 
+def test_controlx_controlx():
+    # At the end: go to the start of the line.
+    result, cli = _feed_cli_with_input('hello world\x18\x18X\n')
+    assert result.text == 'Xhello world'
+    assert result.cursor_position == 1
+
+    # At the start: go to the end of the line.
+    result, cli = _feed_cli_with_input('hello world\x01\x18\x18X\n')
+    assert result.text == 'hello worldX'
+
+    # Left, Left Control-X Control-X: go to the end of the line.
+    result, cli = _feed_cli_with_input('hello world\x1b[D\x1b[D\x18\x18X\n')
+    assert result.text == 'hello worldX'
+
+
 def test_emacs_history_bindings():
     # Adding a new item to the history.
     history = _history()