add support for clearing variables from HttpKernel

src/Microsoft.DotNet.Interactive.ApiCompatibility.Tests/ApiCompatibilityTests.httpRequest_api_is_not_changed.approved.txt

@@ -1,4 +1,6 @@
 Microsoft.DotNet.Interactive.Http
+  public class ClearValues : Microsoft.DotNet.Interactive.Commands.KernelCommand, System.IEquatable<Microsoft.DotNet.Interactive.Commands.KernelCommand>
+    .ctor(System.String targetKernelName = null)
   public class EmptyHttpResponse
     .ctor()
   public class HttpContent
@@ -7,8 +9,9 @@ Microsoft.DotNet.Interactive.Http
     public System.String ContentType { get;}
     public System.Collections.Generic.Dictionary<System.String,System.String[]> Headers { get;}
     public System.String Raw { get;}
-  public class HttpKernel : Microsoft.DotNet.Interactive.Kernel, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestDiagnostics>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestKernelInfo>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestValue>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestValueInfos>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.SendValue>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.SubmitCode>, System.IDisposable
+  public class HttpKernel : Microsoft.DotNet.Interactive.Kernel, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestDiagnostics>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestKernelInfo>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestValue>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.RequestValueInfos>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.SendValue>, Microsoft.DotNet.Interactive.IKernelCommandHandler<Microsoft.DotNet.Interactive.Commands.SubmitCode>, Microsoft.DotNet.Interactive.IKernelCommandHandler<ClearValues>, System.IDisposable
     .ctor(System.String name = null, System.Net.Http.HttpClient client = null, System.Int32 responseDelayThresholdInMilliseconds = 1000, System.Int32 contentByteLengthThreshold = 500000)
+    public System.Threading.Tasks.Task HandleAsync(ClearValues command, Microsoft.DotNet.Interactive.KernelInvocationContext context)
   public class HttpKernelExtension
     public static System.Void Load(Microsoft.DotNet.Interactive.Kernel kernel, System.Net.Http.HttpClient httpClient = null, System.Int32 responseDelayThresholdInMilliseconds = 1000, System.Int32 contentByteLengthThreshold = 500000)
     .ctor()

src/Microsoft.DotNet.Interactive.Http.Tests/HttpKernelTests.cs

@@ -2231,4 +2231,26 @@ public async Task traceparent_header_has_a_new_top_level_value_for_each_request(
         // the traceparent format looks like this: 00-d00689882649007396cd32ab75c2611c-59402ab4fd5c55f7-00
         traceparent1.Single()[0..36].Should().NotBe(traceparent2.Single()[0..36]);
     }
+
+    [Fact]
+    public async Task Variables_can_be_cleared()
+    {
+        using var kernel = new HttpKernel().UseValueSharing();
+
+        var result = await kernel.SendAsync(new SendValue("my_host", "my.host.com"));
+        result.Events.Should().NotContainErrors();
+
+        result = await kernel.SendAsync(new ClearValues());
+        result.Events.Should().NotContainErrors();
+
+        result = await kernel.SendAsync(new RequestValueInfos());
+
+        result.Events.Should().NotContainErrors();
+
+        result.Events.Should().ContainSingle<ValueInfosProduced>()
+              .Which
+              .ValueInfos
+              .Should()
+              .BeEmpty();
+    }
 }

src/Microsoft.DotNet.Interactive.Http/ClearValues.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using Microsoft.DotNet.Interactive.Commands;
+
+namespace Microsoft.DotNet.Interactive.Http;
+
+public class ClearValues : KernelCommand
+{
+    public ClearValues(string? targetKernelName = null) : base(targetKernelName)
+    {
+    }
+}

src/Microsoft.DotNet.Interactive.Http/HttpKernel.cs

@@ -10,11 +10,8 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
-using System.Diagnostics.CodeAnalysis;
-using System.Globalization;
 using System.Linq;
 using System.Net.Http;
-using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -24,6 +21,7 @@ namespace Microsoft.DotNet.Interactive.Http;
 
 public class HttpKernel :
     Kernel,
+    IKernelCommandHandler<ClearValues>,
     IKernelCommandHandler<RequestValue>,
     IKernelCommandHandler<SendValue>,
     IKernelCommandHandler<SubmitCode>,
@@ -58,6 +56,12 @@ This Kernel is able to execute http requests and display the results.
         RegisterForDisposal(_client);
     }
 
+    public Task HandleAsync(ClearValues command, KernelInvocationContext context)
+    {
+        _variables.Clear();
+        return Task.CompletedTask;
+    }
+
     Task IKernelCommandHandler<RequestValue>.HandleAsync(RequestValue command, KernelInvocationContext context)
     {
         if (_variables.TryGetValue(command.Name, out var value))

src/Microsoft.DotNet.Interactive.Tests/Connection/SerializationTests.Command_contract_has_not_been_broken.approved.ClearValues.json

@@ -0,0 +1,13 @@
+{
+  "token": "the-token",
+  "commandType": "ClearValues",
+  "command": {
+    "targetKernelName": null,
+    "originUri": null,
+    "destinationUri": null
+  },
+  "routingSlip": [
+    "kernel://somelocation/kernelName?tag=arrived",
+    "kernel://somelocation/kernelName"
+  ]
+}

src/Microsoft.DotNet.Interactive.Tests/Connection/SerializationTests.cs

@@ -14,8 +14,12 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.DotNet.Interactive.Commands;
 using Microsoft.DotNet.Interactive.Connection;
+using Microsoft.DotNet.Interactive.CSharp;
 using Microsoft.DotNet.Interactive.Events;
 using Microsoft.DotNet.Interactive.Formatting;
+using Microsoft.DotNet.Interactive.FSharp;
+using Microsoft.DotNet.Interactive.Http;
+using Microsoft.DotNet.Interactive.PowerShell;
 using Microsoft.DotNet.Interactive.Tests.Utility;
 using Microsoft.DotNet.Interactive.ValueSharing;
 using Pocket;
@@ -120,11 +124,20 @@ public void Event_contract_has_not_been_broken(KernelEvent @event)
     [Fact]
     public void All_command_types_are_tested_for_round_trip_serialization()
     {
-        var interactiveCommands = typeof(Kernel)
-            .Assembly
-            .ExportedTypes
-            .Concrete()
-            .DerivedFrom(typeof(KernelCommand));
+        var commandTypes = new[]
+                           {
+                               typeof(Kernel),
+                               typeof(CSharpKernel),
+                               typeof(FSharpKernel),
+                               typeof(HttpKernel),
+                               typeof(PowerShellKernel),
+                           }
+                           .Select(t => t.Assembly)
+                           .SelectMany(a => a.ExportedTypes);
+
+        var interactiveCommands = commandTypes
+                                  .Concrete()
+                                  .DerivedFrom(typeof(KernelCommand));
 
         Commands()
             .Select(e => e[0].GetType())
@@ -163,6 +176,8 @@ public static IEnumerable<object[]> Commands()
 
         IEnumerable<KernelCommand> commands()
         {
+            yield return new ClearValues();
+
             yield return new DisplayError("oops!");
 
             yield return new DisplayValue(

src/Microsoft.DotNet.Interactive.Tests/Microsoft.DotNet.Interactive.Tests.csproj

@@ -75,6 +75,7 @@
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.CSharp\Microsoft.DotNet.Interactive.CSharp.csproj" />
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.Formatting.Tests\Microsoft.DotNet.Interactive.Formatting.Tests.csproj" />
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.FSharp\Microsoft.DotNet.Interactive.FSharp.fsproj" />
+    <ProjectReference Include="..\Microsoft.DotNet.Interactive.Http\Microsoft.DotNet.Interactive.Http.csproj" />
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.PowerShell\Microsoft.DotNet.Interactive.PowerShell.csproj" />
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.Jupyter\Microsoft.DotNet.Interactive.Jupyter.csproj" />
     <ProjectReference Include="..\Microsoft.DotNet.Interactive.Formatting\Microsoft.DotNet.Interactive.Formatting.csproj" />