[Backport to 4.1] Validates composition can be called multiple times (#830) (#831)

* Add a test that validates composition can be called multiple times (#830)

* Use the correct context (#803)

Related to #802

Author: mauroservienti

src/ServiceComposer.AspNetCore.Tests/Get_with_2_handlers.cs

@@ -75,6 +75,45 @@ public async Task Returns_expected_response()
             Assert.Equal("sample", responseObj?.SelectToken("AString")?.Value<string>());
             Assert.Equal(1, responseObj?.SelectToken("ANumber")?.Value<int>());
         }
+        
+        [Fact]
+        public async Task Returns_expected_response_when_invoked_more_than_once()
+        {
+            // Arrange
+            var client = new SelfContainedWebApplicationFactoryWithWebHost<Dummy>
+            (
+                configureServices: services =>
+                {
+                    services.AddViewModelComposition(options =>
+                    {
+                        options.AssemblyScanner.Disable();
+                        options.RegisterCompositionHandler<TestGetStringHandler>();
+                        options.RegisterCompositionHandler<TestGetIntegerHandler>();
+                    });
+                    services.AddRouting();
+                    services.AddControllers();
+                },
+                configure: app =>
+                {
+                    app.UseRouting();
+                    app.UseEndpoints(builder => builder.MapCompositionHandlers());
+                }
+            ).CreateClient();
+
+            client.DefaultRequestHeaders.Add("Accept-Casing", "casing/pascal");
+            // Act
+            _ = await client.GetAsync("/sample/1");
+            var response = await client.GetAsync("/sample/1");
+
+            // Assert
+            Assert.True(response.IsSuccessStatusCode);
+
+            var responseString = await response.Content.ReadAsStringAsync();
+            var responseObj = JObject.Parse(responseString);
+
+            Assert.Equal("sample", responseObj?.SelectToken("AString")?.Value<string>());
+            Assert.Equal(1, responseObj?.SelectToken("ANumber")?.Value<int>());
+        }
 
         [Fact]
         public async Task Returns_expected_response_using_output_formatters()

src/ServiceComposer.AspNetCore/CompositionEndpointBuilder.cs

@@ -106,7 +106,7 @@ public override Endpoint Build()
 
                 RequestDelegate composer = async composerHttpContext =>
                 {
-                    var requestId = context.EnsureRequestIdIsSetup();
+                    var requestId = composerHttpContext.EnsureRequestIdIsSetup();
                     var compositionContext = new CompositionContext
                     (
                         requestId,
@@ -166,4 +166,4 @@ public override Endpoint Build()
             return routeEndpoint;
         }
     }
-}
+}