Add Slider Automation Test

samples/IntegrationTestApp/MainWindow.axaml

@@ -151,6 +151,9 @@
           </StackPanel>
         </Grid>
       </TabItem>
+      <TabItem Header="Slider">
+          <Slider Name="Slider2" Value="30"/>
+      </TabItem>
     </TabControl>
   </DockPanel>
 </Window>

tests/Avalonia.IntegrationTests.Appium/SliderTests.cs

@@ -0,0 +1,35 @@
+using System;
+using OpenQA.Selenium.Appium;
+using OpenQA.Selenium.Interactions;
+using Xunit;
+
+namespace Avalonia.IntegrationTests.Appium
+{
+    [Collection("Default")]
+    public class SliderTests
+    {
+        private readonly AppiumDriver<AppiumWebElement> _session;
+
+        public SliderTests(TestAppFixture fixture)
+        {
+            _session = fixture.Session;
+
+            var tabs = _session.FindElementByAccessibilityId("MainTabs");
+            var tab = tabs.FindElementByName("Slider");
+            tab.Click();
+        }
+
+        [Fact]
+        public void Changes_Value_When_Moving_Slider()
+        {
+            var slider = _session.FindElementByAccessibilityId("Slider2");
+
+            // slider.Text gets the Slider value
+            Assert.True(double.Parse(slider.Text) == 30);
+
+            new Actions(_session).Click(slider).MoveByOffset(100, 0).Perform();
+
+            Assert.Equal(50, Math.Round(double.Parse(slider.Text)));
+        }
+    }
+}