Uno.WindowsCommunityToolkit/SmokeTests/CommunityToolkit.Common/MainPage.xaml

<Page
    x:Class="SmokeTest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:SmokeTest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <Grid>
        <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center" Width="200">
            <TextBox x:Name="textBox"/>
            <Button Content="Is Email?" Click="Button_Click" HorizontalAlignment="Center"/>
            <TextBlock x:Name="textBlock"/>
        </StackPanel>
    </Grid>
</Page>