Added keyboard navigation support

tests/controls/test_datagrid.py

@@ -372,6 +372,102 @@ class TestDataGridBehaviour:
     assert col_def.type == ColumnType.Number
     assert col_def.formula == "{age} + 1"
 
+  # ------------------------------------------------------------------
+  # Keyboard Navigation
+  # ------------------------------------------------------------------
+  # Column layout for datagrid_with_data (enable_edition=True):
+  #   _state.columns : [name (idx 0), age (idx 1), active (idx 2)]
+  #   _columns       : [RowSelection_ (pos 0), name (pos 1), age (pos 2), active (pos 3)]
+  # Navigable positions: [1, 2, 3]  —  RowSelection_ (pos 0) always excluded.
+
+  def test_i_can_get_navigable_col_positions(self, datagrid_with_data):
+    """RowSelection_ (pos 0) must be excluded; data columns (1, 2, 3) must be included."""
+    positions = datagrid_with_data._get_navigable_col_positions()
+    assert positions == [1, 2, 3]
+
+  def test_i_can_get_navigable_col_positions_with_hidden_column(self, datagrid_with_data):
+    """Hidden columns must be excluded from navigable positions.
+
+    _state.columns[1] is 'age' → maps to _columns pos 2.
+    After hiding, navigable positions must be [1, 3].
+    """
+    datagrid_with_data._state.columns[1].visible = False  # hide 'age' (pos 2 in _columns)
+    datagrid_with_data._init_columns()
+    positions = datagrid_with_data._get_navigable_col_positions()
+    assert positions == [1, 3]
+
+  @pytest.mark.parametrize("start_pos, direction, expected_pos", [
+      # Normal navigation — right / left
+      ((1, 0), "right", (2, 0)),
+      ((2, 0), "right", (3, 0)),
+      ((3, 0), "left",  (2, 0)),
+      ((2, 0), "left",  (1, 0)),
+      # Normal navigation — down / up
+      ((1, 0), "down",  (1, 1)),
+      ((1, 1), "down",  (1, 2)),
+      ((1, 2), "up",    (1, 1)),
+      ((1, 1), "up",    (1, 0)),
+      # Boundaries — must stay in place
+      ((3, 0), "right", (3, 0)),
+      ((1, 0), "left",  (1, 0)),
+      ((1, 2), "down",  (1, 2)),
+      ((1, 0), "up",    (1, 0)),
+  ])
+  def test_i_can_navigate(self, datagrid_with_data, start_pos, direction, expected_pos):
+    """Navigation moves to the expected position or stays at boundary."""
+    result = datagrid_with_data._navigate(start_pos, direction)
+    assert result == expected_pos
+
+  def test_i_can_navigate_right_skipping_invisible_column(self, datagrid_with_data):
+    """→ from col 1 must skip hidden col 2 (age) and land on col 3 (active)."""
+    datagrid_with_data._state.columns[1].visible = False  # hide 'age' → pos 2
+    datagrid_with_data._init_columns()
+    result = datagrid_with_data._navigate((1, 0), "right")
+    assert result == (3, 0)
+
+  def test_i_can_navigate_left_skipping_invisible_column(self, datagrid_with_data):
+    """← from col 3 must skip hidden col 2 (age) and land on col 1 (name)."""
+    datagrid_with_data._state.columns[1].visible = False  # hide 'age' → pos 2
+    datagrid_with_data._init_columns()
+    result = datagrid_with_data._navigate((3, 0), "left")
+    assert result == (1, 0)
+
+  def test_i_can_navigate_down_skipping_filtered_row(self, datagrid_with_data):
+    """↓ from row 0 must skip filtered-out row 1 (Bob) and land on row 2 (Charlie).
+
+    Filter keeps age values "25" and "35" only → row 1 (age=30) is excluded.
+    Visible row indices become [0, 2].
+    """
+    datagrid_with_data._state.filtered["age"] = ["25", "35"]
+    result = datagrid_with_data._navigate((1, 0), "down")
+    assert result == (1, 2)
+
+  @pytest.mark.parametrize("combination, start_pos, expected_pos", [
+      ("arrowright", (1, 0), (2, 0)),
+      ("arrowleft",  (2, 0), (1, 0)),
+      ("arrowdown",  (1, 0), (1, 1)),
+      ("arrowup",    (1, 1), (1, 0)),
+  ])
+  def test_i_can_navigate_with_arrow_keys(self, datagrid_with_data, combination, start_pos, expected_pos):
+    """Arrow key presses update selection.selected to the expected position."""
+    datagrid_with_data._state.selection.selected = start_pos
+    datagrid_with_data.on_key_pressed(combination=combination, has_focus=True, is_inside=True)
+    assert datagrid_with_data._state.selection.selected == expected_pos
+
+  def test_i_can_navigate_from_last_selected_when_no_selection(self, datagrid_with_data):
+    """When selected is None, navigation starts from last_selected."""
+    datagrid_with_data._state.selection.selected = None
+    datagrid_with_data._state.selection.last_selected = (1, 1)
+    datagrid_with_data.on_key_pressed(combination="arrowright", has_focus=True, is_inside=True)
+    assert datagrid_with_data._state.selection.selected == (2, 1)
+
+  def test_i_can_navigate_from_origin_when_no_selection_and_no_last_selected(self, datagrid_with_data):
+    """When both selected and last_selected are None, navigation starts from (0, 0)."""
+    datagrid_with_data._state.selection.selected = None
+    datagrid_with_data._state.selection.last_selected = None
+    datagrid_with_data.on_key_pressed(combination="arrowright", has_focus=True, is_inside=True)
+    assert datagrid_with_data._state.selection.selected == (1, 0)
+
 
 class TestDataGridRender: