value kernel honours content type in --from-url

src/Microsoft.DotNet.Interactive.Tests/KeyValueStoreKernelTests.cs

@@ -191,7 +191,7 @@ public async Task It_can_import_URL_contents_as_strings()
     {
         using var kernel = CreateKernel();
 
-        await kernel.SubmitCodeAsync("#!value --name hi --from-url http://bing.com");
+        await kernel.SubmitCodeAsync("#!value --name hi --from-url https://bing.com");
 
         var keyValueStoreKernel = kernel.FindKernelByName("value");
 
@@ -202,6 +202,22 @@ public async Task It_can_import_URL_contents_as_strings()
             .Contain("<html");
     }
 
+    [Fact]
+    public async Task When_import_URL_contents_the_mimetype_is_preserved()
+    {
+        using var kernel = CreateKernel();
+
+        await kernel.SubmitCodeAsync("#!value --name hi --from-url https://bing.com");
+
+        var keyValueStoreKernel = kernel.FindKernelByName("value");
+
+        var valueProduced = await keyValueStoreKernel.RequestValueAsync("hi");
+
+        valueProduced.FormattedValue.MimeType
+            .Should()
+            .Be("text/html");
+    }
+
     [Fact]
     public async Task It_can_store_user_input()
     {

src/Microsoft.DotNet.Interactive/KeyValueStoreKernel.cs

@@ -91,6 +91,7 @@ internal async Task TryStoreValueFromOptionsAsync(
         KernelInvocationContext context,
         ValueDirectiveOptions options)
     {
+        var mimeType = options.MimeType;
         string newValue = null;
         var loadedFromOptions = false;
 
@@ -104,6 +105,7 @@ internal async Task TryStoreValueFromOptionsAsync(
             var client = new HttpClient();
             var response = await client.GetAsync(uri, context.CancellationToken);
             newValue = await response.Content.ReadAsStringAsync();
+            mimeType ??= response.Content.Headers?.ContentType?.MediaType;
             loadedFromOptions = true;
         }
         else if (options.FromValue is { } value)
@@ -118,7 +120,7 @@ internal async Task TryStoreValueFromOptionsAsync(
 
             _lastOperation = (hadValue, previousValue, newValue);
 
-            StoreValue(newValue, options, context);
+            StoreValue(newValue, options, context, mimeType: mimeType);
         }
         else
         {
@@ -130,7 +132,8 @@ private void StoreValue(
         KernelCommand command, 
         KernelInvocationContext context, 
         ValueDirectiveOptions options,
-        string value = null)
+        string value = null,
+        string mimeType = null)
     {
         if (options.FromFile is { })
         {
@@ -153,7 +156,7 @@ private void StoreValue(
         }
         else
         {
-            StoreValue(value, options, context);
+            StoreValue(value, options, context, mimeType: mimeType);
         }
 
         _lastOperation = default;
@@ -181,13 +184,16 @@ void UndoSetValue()
     private void StoreValue(
         string value,
         ValueDirectiveOptions options,
-        KernelInvocationContext context)
+        KernelInvocationContext context,
+        string mimeType = null)
+
     {
-        _values[options.Name] = new FormattedValue(options.MimeType ?? PlainTextFormatter.MimeType, value);
+        mimeType ??= ( options.MimeType ?? PlainTextFormatter.MimeType);
+        _values[options.Name] = new FormattedValue(mimeType, value);
 
-        if (options.MimeType is { } mimeType)
+        if (options.MimeType is {} displayMimeType)
         {
-            context.DisplayAs(value, mimeType);
+            context.DisplayAs(value, displayMimeType);
         }
     }
 }