ServiceEndpoint.ToString(): omit zero port (dotnet#4015)

Author: ReubenBond

src/Microsoft.Extensions.ServiceDiscovery.Abstractions/Internal/ServiceEndpointImpl.cs

@@ -9,9 +9,13 @@ namespace Microsoft.Extensions.ServiceDiscovery.Internal;
 internal sealed class ServiceEndpointImpl(EndPoint endPoint, IFeatureCollection? features = null) : ServiceEndpoint
 {
     public override EndPoint EndPoint { get; } = endPoint;
+
     public override IFeatureCollection Features { get; } = features ?? new FeatureCollection();
+
     public override string? ToString() => EndPoint switch
     {
+        IPEndPoint ip when ip.Port == 0 => $"{ip.Address}",
+        DnsEndPoint dns when dns.Port == 0 => $"{dns.Host}",
         DnsEndPoint dns => $"{dns.Host}:{dns.Port}",
         _ => EndPoint.ToString()!
     };

tests/Microsoft.Extensions.ServiceDiscovery.Tests/ServiceEndpointTests.cs

@@ -0,0 +1,42 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Net;
+using Xunit;
+
+namespace Microsoft.Extensions.ServiceDiscovery.Tests;
+
+public class ServiceEndpointTests
+{
+    public static TheoryData<EndPoint> ZeroPortEndPoints => new()
+    {
+        IPEndPoint.Parse("127.0.0.1:0"),
+        new DnsEndPoint("microsoft.com", 0),
+        new UriEndPoint(new Uri("https://microsoft.com"))
+    };
+
+    public static TheoryData<EndPoint> NonZeroPortEndPoints => new()
+    {
+        IPEndPoint.Parse("127.0.0.1:8443"),
+        new DnsEndPoint("microsoft.com", 8443),
+        new UriEndPoint(new Uri("https://microsoft.com:8443"))
+    };
+
+    [Theory]
+    [MemberData(nameof(ZeroPortEndPoints))]
+    public void ServiceEndpointToStringOmitsUnspecifiedPort(EndPoint endpoint)
+    {
+        var serviceEndpoint = ServiceEndpoint.Create(endpoint);
+        var epString = serviceEndpoint.ToString();
+        Assert.DoesNotContain(":0", epString);
+    }
+
+    [Theory]
+    [MemberData(nameof(NonZeroPortEndPoints))]
+    public void ServiceEndpointToStringContainsSpecifiedPort(EndPoint endpoint)
+    {
+        var serviceEndpoint = ServiceEndpoint.Create(endpoint);
+        var epString = serviceEndpoint.ToString();
+        Assert.Contains(":8443", epString);
+    }
+}