chore: use of async life time for test initialization

Signed-off-by: Vincent Biret <[email protected]>

Author: baywet

test/Microsoft.OpenApi.Tests/Models/References/OpenApiCallbackReferenceTests.cs

@@ -17,7 +17,7 @@
 namespace Microsoft.OpenApi.Tests.Models.References
 {
     [Collection("DefaultSettings")]
-    public class OpenApiCallbackReferenceTests
+    public class OpenApiCallbackReferenceTests : IAsyncLifetime
     {
         // OpenApi doc with external $ref
         private const string OpenApi = @"
@@ -128,20 +128,29 @@ public class OpenApiCallbackReferenceTests
             '200':
               description: ok";
 
-        private readonly OpenApiCallbackReference _externalCallbackReference;
-        private readonly OpenApiCallbackReference _localCallbackReference;
+        private OpenApiCallbackReference _externalCallbackReference;
+        private OpenApiCallbackReference _localCallbackReference;
 
         public OpenApiCallbackReferenceTests()
         {
             OpenApiReaderRegistry.RegisterReader(OpenApiConstants.Yaml, new OpenApiYamlReader());
-            OpenApiDocument openApiDoc = OpenApiDocument.ParseAsync(OpenApi).GetAwaiter().GetResult().OpenApiDocument;
-            OpenApiDocument openApiDoc_2 = OpenApiDocument.ParseAsync(OpenApi_2).GetAwaiter().GetResult().OpenApiDocument;
+        }
+
+        public async Task InitializeAsync()
+        {
+            OpenApiDocument openApiDoc = (await OpenApiDocument.ParseAsync(OpenApi)).OpenApiDocument;
+            OpenApiDocument openApiDoc_2 = (await OpenApiDocument.ParseAsync(OpenApi_2)).OpenApiDocument;
             openApiDoc.Workspace.AddDocumentId("https://myserver.com/beta", openApiDoc_2.BaseUri);
             openApiDoc.Workspace.RegisterComponents(openApiDoc_2);
             _externalCallbackReference = new("callbackEvent", openApiDoc, "https://myserver.com/beta");
             _localCallbackReference = new("callbackEvent", openApiDoc_2);
         }
 
+        public Task DisposeAsync()
+        {
+            return Task.CompletedTask;
+        }
+
         [Fact]
         public void CallbackReferenceResolutionWorks()
         {