simplify add method, complex adds can use [] (#194)

* simplify add method, complex adds can use []

* cleanup test layout

bowtie/_app.py

@@ -323,24 +323,37 @@ def __setitem__(self, key, widget):
                     raise GridIndexError(
                         'Cannot index with {}, pass in a int or a slice.'.format(column_key)
                     )
-                self.add(
+                self._add(
                     widget, row_start=row_start, column_start=column_start,
                     row_end=row_end, column_end=column_end
                 )
 
         elif isinstance(key, slice):
             start, end = _slice_to_start_end(key, len(self.rows))
-            self.add(
+            self._add(
                 widget, row_start=start, column_start=0,
                 row_end=end, column_end=len(self.columns)
             )
         elif isinstance(key, int):
-            self.add(widget, row_start=key, column_start=0, column_end=len(self.columns))
+            self._add(widget, row_start=key, column_start=0, column_end=len(self.columns))
         else:
             raise GridIndexError('Invalid index {}'.format(key))
 
-    def add(self, widget, row_start=None, column_start=None,
-            row_end=None, column_end=None):
+    def add(self, widget):
+        """Add a widget to the grid in the next available cell.
+
+        Searches over columns then rows for available cells.
+
+        Parameters
+        ----------
+        widget : bowtie._Component
+            A Bowtie widget instance.
+
+        """
+        self._add(widget)
+
+    def _add(self, widget, row_start=None, column_start=None,
+             row_end=None, column_end=None):
         """Add a widget to the grid.
 
         Zero-based index and exclusive.
@@ -577,28 +590,19 @@ def __setitem__(self, key, value):
         """Add widget to the root view."""
         self.root.__setitem__(key, value)
 
-    def add(self, widget, row_start=None, column_start=None,
-            row_end=None, column_end=None):
-        """Add a widget to the grid.
+    def add(self, widget):
+        """Add a widget to the grid in the next available cell.
 
-        Zero-based index and inclusive.
+        Searches over columns then rows for available cells.
 
         Parameters
         ----------
         widget : bowtie._Component
             A Bowtie widget instance.
-        row_start : int, optional
-            Starting row for the widget.
-        column_start : int, optional
-            Starting column for the widget.
-        row_end : int, optional
-            Ending row for the widget.
-        column_end : int, optional
-            Ending column for the widget.
 
         """
-        self.root.add(widget, row_start=row_start, column_start=column_start,
-                      row_end=row_end, column_end=column_end)
+        # pylint: disable=protected-access
+        self.root._add(widget)
 
     def add_sidebar(self, widget):
         """Add a widget to the sidebar.

bowtie/tests/test_layout.py

@@ -6,7 +6,7 @@
 
 from bowtie import App
 from bowtie.control import Button
-from bowtie._app import MissingRowOrColumn, GridIndexError, UsedCellsError, NoUnusedCellsError
+from bowtie._app import GridIndexError, UsedCellsError, NoUnusedCellsError
 
 
 @pytest.fixture(scope='module')
@@ -20,31 +20,6 @@ def app():
     return App(rows=2, columns=2)
 
 
-def test_no_row(buttons):
-    """Test missing row."""
-
-    app = App(rows=2, columns=3)
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], column_start=0, column_end=3)
-
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], column_start=0)
-
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], column_end=1)
-
-
-def test_no_column(buttons):
-    """Test missing column."""
-
-    app = App(rows=2, columns=3)
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], row_start=0, row_end=2)
-
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], row_start=0)
-
-
 def test_all_used(buttons):
     """Test all cells are used."""
 
@@ -84,29 +59,31 @@ def test_used(buttons):
         app.add(buttons[i])
 
     with pytest.raises(UsedCellsError):
-        app.add(buttons[3], row_start=0, column_start=0)
+        app[0, 0] = buttons[3]
 
     with pytest.raises(UsedCellsError):
-        app.add(buttons[3], row_start=0, column_start=1, row_end=1)
+        app[0:1, 1] = buttons[3]
 
     with pytest.raises(UsedCellsError):
-        app.add(buttons[3], row_start=1, column_start=0, column_end=1)
+        app[1, 0:1] = buttons[3]
 
-    app.add(buttons[3], row_start=1, column_start=1)
+    app[1, 1] = buttons[3]
 
 
 def test_grid_index(buttons):
     """Test grid indexing checks."""
 
     app = App(rows=2, columns=2)
     with pytest.raises(GridIndexError):
-        app.add(buttons[0], row_start=-5)
+        app[-5] = buttons[0]
 
-    with pytest.raises(MissingRowOrColumn):
-        app.add(buttons[0], row_start=-1)
+    app[-1] = buttons[0]
 
     with pytest.raises(GridIndexError):
-        app.add(buttons[0], row_start=2)
+        app[2] = buttons[0]
+
+    with pytest.raises(UsedCellsError):
+        app[1] = buttons[0]
 
 
 def test_getitem(buttons):