test for animation

tests/test_animation.py

@@ -0,0 +1,33 @@
+from time import time
+from textual.app import App, ComposeResult
+from textual.widgets import Static
+
+
+class AnimApp(App):
+    CSS = """
+    #foo {
+        height: 1;
+    }
+    
+    """
+
+    def compose(self) -> ComposeResult:
+        yield Static("foo", id="foo")
+
+
+async def test_animate_height() -> None:
+    """Test animating styles.height works."""
+
+    # Styles.height is a scalar, which makes it more complicated to animate
+
+    app = AnimApp()
+
+    async with app.run_test() as pilot:
+        static = app.query_one(Static)
+        assert static.size.height == 1
+        static.styles.animate("height", 100, duration=0.5)
+        start = time()
+        await pilot.wait_for_animation()
+        elapsed = time() - start
+        assert elapsed > 0.5
+        assert static.styles.height.value == 100