Add Span Example in test proj

Author: mythz

tests/ServiceStack.Text.Tests/ServiceStack.Text.Tests.csproj

@@ -26,6 +26,7 @@
     <PackageReference Include="NUnit" Version="3.9.0" />
     <PackageReference Include="protobuf-net" Version="2.3.2" />
     <PackageReference Include="System.ValueTuple" Version="4.4.0" />
+    <PackageReference Include="System.Memory" Version="4.4.0-preview1-25305-02" />
   </ItemGroup>
   <PropertyGroup Condition=" '$(TargetFramework)' == 'net45' ">
     <DefineConstants>$(DefineConstants);NET45</DefineConstants>

tests/ServiceStack.Text.Tests/SpanTests.cs

@@ -0,0 +1,19 @@
+using System;
+using NUnit.Framework;
+
+namespace ServiceStack.Text.Tests
+{
+    public class SpanTests
+    {
+        [Test]
+        public void Can_use_Span()
+        {
+            //.AsReadOnlySpan() not available in System.Memory v4.4.0-preview1-25305-02 on NuGet yet
+            ReadOnlySpan<char> a = "foo bar".AsSpan();
+
+            var foo = a.Slice(0,3).ToArray();
+
+            Assert.That(foo, Is.EqualTo("foo".ToCharArray()));
+        }
+    }
+}