Fix returning arrays in async JS interop calls. Fixes #1205

src/Microsoft.JSInterop/JSRuntimeBase.cs

@@ -100,10 +100,12 @@ namespace Microsoft.JSInterop
             if (succeeded)
             {
                 var resultType = TaskGenericsUtil.GetTaskCompletionSourceResultType(tcs);
-                var resultValue = resultOrException is SimpleJson.JsonObject
-                    ? ArgSerializerStrategy.DeserializeObject(resultOrException, resultType)
-                    : resultOrException;
-                TaskGenericsUtil.SetTaskCompletionSourceResult(tcs, resultValue);
+                if (resultOrException is SimpleJson.JsonObject || resultOrException is SimpleJson.JsonArray)
+                {
+                    resultOrException = ArgSerializerStrategy.DeserializeObject(resultOrException, resultType);
+                }
+
+                TaskGenericsUtil.SetTaskCompletionSourceResult(tcs, resultOrException);
             }
             else
             {

test/Microsoft.AspNetCore.Blazor.E2ETest/Tests/InteropTest.cs

@@ -59,6 +59,7 @@ namespace Microsoft.AspNetCore.Blazor.E2ETest.Tests
                 ["testDtoNonSerializedValueAsync"] = "99999",
                 ["testDtoAsync"] = "Same",
                 ["returnPrimitiveAsync"] = "123",
+                ["returnArrayAsync"] = "first,second",
             };
 
             var expectedSyncValues = new Dictionary<string, string>
@@ -92,6 +93,7 @@ namespace Microsoft.AspNetCore.Blazor.E2ETest.Tests
                 ["testDtoNonSerializedValueSync"] = "99999",
                 ["testDtoSync"] = "Same",
                 ["returnPrimitive"] = "123",
+                ["returnArray"] = "first,second",
             };
 
             // Include the sync assertions only when running under WebAssembly

test/testapps/BasicTestApp/InteropComponent.cshtml

@@ -122,9 +122,11 @@
         ReceiveDotNetObjectByRefAsyncResult["testDto"] = ReceiveDotNetObjectByRefAsyncResult["testDto"] == passDotNetObjectByRef ? "Same" : "Different";
 
         ReturnValues["returnPrimitiveAsync"] = (await JSRuntime.Current.InvokeAsync<int>("returnPrimitiveAsync")).ToString();
+        ReturnValues["returnArrayAsync"] = string.Join(",", (await JSRuntime.Current.InvokeAsync<Segment[]>("returnArrayAsync")).Select(x => x.Source).ToArray());
         if (shouldSupportSyncInterop)
         {
             ReturnValues["returnPrimitive"] = ((IJSInProcessRuntime)JSRuntime.Current).Invoke<int>("returnPrimitive").ToString();
+            ReturnValues["returnArray"] = string.Join(",", ((IJSInProcessRuntime)JSRuntime.Current).Invoke<Segment[]>("returnArray").Select(x => x.Source).ToArray());
         }
 
         Invocations = invocations;

test/testapps/BasicTestApp/wwwroot/js/jsinteroptests.js

@@ -186,6 +186,18 @@ function returnPrimitiveAsync() {
   });
 }
 
+function returnArray() {
+  return [{ source: 'first' }, { source: 'second' }];
+}
+
+function returnArrayAsync() {
+  return new Promise((resolve, reject) => {
+    setTimeout(function () {
+      resolve(returnArray());
+    }, 100);
+  });
+}
+
 function functionThrowsException() {
   throw new Error('Function threw an exception!');
 }