Horizontal width auto (#1155)

* Improvements to width:auto HorizontalLayout

* Fix HorizontalLayout.get_content_width

* Horizontal width auto improvement

* Removing some printxz

* Update snapshot for horizontal layout width auto dock

tests/layouts/test_horizontal.py

@@ -1,46 +1,29 @@
-from textual.geometry import Size
-from textual.layouts.horizontal import HorizontalLayout
+import pytest
+
+from textual.app import App, ComposeResult
+from textual.containers import Horizontal
 from textual.widget import Widget
 
 
-class SizedWidget(Widget):
-    """Simple Widget wrapped allowing you to modify the return values for
-    get_content_width and get_content_height via the constructor."""
+@pytest.fixture
+async def app():
+    class HorizontalAutoWidth(App):
+        def compose(self) -> ComposeResult:
+            child1 = Widget(id="child1")
+            child1.styles.width = 4
+            child2 = Widget(id="child2")
+            child2.styles.width = 6
+            child3 = Widget(id="child3")
+            child3.styles.width = 5
+            self.horizontal = Horizontal(child1, child2, child3)
+            yield self.horizontal
 
-    def __init__(
-        self,
-        *children: Widget,
-        content_width: int = 10,
-        content_height: int = 5,
-    ):
-        super().__init__(*children)
-        self.content_width = content_width
-        self.content_height = content_height
-
-    def get_content_width(self, container: Size, viewport: Size) -> int:
-        return self.content_width
-
-    def get_content_height(self, container: Size, viewport: Size, width: int) -> int:
-        return self.content_height
+    app = HorizontalAutoWidth()
+    async with app.run_test():
+        yield app
 
 
-CHILDREN = [
-    SizedWidget(content_width=10, content_height=5),
-    SizedWidget(content_width=4, content_height=2),
-    SizedWidget(content_width=12, content_height=3),
-]
-
-
-def test_horizontal_get_content_width():
-    parent = Widget(*CHILDREN)
-    layout = HorizontalLayout()
-    width = layout.get_content_width(widget=parent, container=Size(), viewport=Size())
-    assert width == sum(child.content_width for child in CHILDREN)
-
-
-def test_horizontal_get_content_width_no_children():
-    parent = Widget()
-    layout = HorizontalLayout()
-    container_size = Size(24, 24)
-    width = layout.get_content_width(widget=parent, container=container_size, viewport=Size())
-    assert width == container_size.width
+async def test_horizontal_get_content_width(app):
+    size = app.screen.size
+    width = app.horizontal.get_content_width(size, size)
+    assert width == 15