Upgrade to xunit 2.3.0-beta4

build/dependencies.props

@@ -6,7 +6,8 @@
     <NETStandardImplicitPackageVersion>2.0.0-*</NETStandardImplicitPackageVersion>
     <NETStandardLibraryNETFrameworkVersion>2.0.0-*</NETStandardLibraryNETFrameworkVersion>
     <RuntimeFrameworkVersion Condition="'$(TargetFramework)'=='netcoreapp2.0'">2.0.0-*</RuntimeFrameworkVersion>
-    <TestSdkVersion>15.3.0-*</TestSdkVersion>
+    <TestSdkVersion>15.3.0</TestSdkVersion>
-    <XunitVersion>2.3.0-beta2-*</XunitVersion>
+    <XunitAnalyzersVersion>0.6.1</XunitAnalyzersVersion>
+    <XunitVersion>2.3.0-beta4-build3742</XunitVersion>
   </PropertyGroup>
 </Project>

test/Microsoft.AspNetCore.Cors.Test/CorsMiddlewareTests.cs

@@ -45,7 +45,7 @@ namespace Microsoft.AspNetCore.Cors.Infrastructure
 
                 // Assert
                 response.EnsureSuccessStatusCode();
-                Assert.Equal(1, response.Headers.Count());
+                Assert.Single(response.Headers);
                 Assert.Equal("Cross origin response", await response.Content.ReadAsStringAsync());
                 Assert.Equal("http://localhost:5001", response.Headers.GetValues(CorsConstants.AccessControlAllowOrigin).FirstOrDefault());
             }
@@ -124,7 +124,7 @@ namespace Microsoft.AspNetCore.Cors.Infrastructure
 
                 // Assert
                 response.EnsureSuccessStatusCode();
-                Assert.Equal(1, response.Headers.Count());
+                Assert.Single(response.Headers);
                 Assert.Equal("http://localhost:5001", response.Headers.GetValues(CorsConstants.AccessControlAllowOrigin).FirstOrDefault());
             }
         }