Set AuthenticationMethod for first Identity external login (#18296)

src/Identity/UI/src/Areas/Identity/Pages/V3/Account/ExternalLogin.cshtml.cs

@@ -215,7 +215,7 @@ namespace Microsoft.AspNetCore.Identity.UI.V3.Pages.Account.Internal
                             return RedirectToPage("./RegisterConfirmation", new { Email = Input.Email });
                         }
 
-                        await _signInManager.SignInAsync(user, isPersistent: false);
+                        await _signInManager.SignInAsync(user, isPersistent: false, info.LoginProvider);
 
                         return LocalRedirect(returnUrl);
                     }

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/ExternalLogin.cshtml.cs

@@ -212,7 +212,7 @@ namespace Microsoft.AspNetCore.Identity.UI.V4.Pages.Account.Internal
                             return RedirectToPage("./RegisterConfirmation", new { Email = Input.Email });
                         }
 
-                        await _signInManager.SignInAsync(user, isPersistent: false);
+                        await _signInManager.SignInAsync(user, isPersistent: false, info.LoginProvider);
                         return LocalRedirect(returnUrl);
                     }
                 }

src/Identity/test/Identity.FunctionalTests/RegistrationTests.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Security.Claims;
 using System.Threading.Tasks;
 using Identity.DefaultUI.WebSite;
 using Microsoft.AspNetCore.Identity.UI.Services;
@@ -218,5 +219,31 @@ namespace Microsoft.AspNetCore.Identity.FunctionalTests
             // Act & Assert
             await UserStories.RegisterNewUserWithSocialLoginAsync(client, userName, email);
         }
+
+        [Fact]
+        public async Task RegisterWithASocialLoginProviderSetsAuthenticationMethodClaim()
+        {
+            // Arrange
+            string authenticationMethod = null;
+
+            void ConfigureTestServices(IServiceCollection services) =>
+                services
+                    .SetupTestThirdPartyLogin()
+                    .SetupGetUserClaimsPrincipal(user =>
+                        authenticationMethod = user.FindFirstValue(ClaimTypes.AuthenticationMethod), IdentityConstants.ApplicationScheme);
+
+            var client = ServerFactory
+                .WithWebHostBuilder(whb => whb.ConfigureServices(ConfigureTestServices))
+                .CreateClient();
+
+            var guid = Guid.NewGuid();
+            var userName = $"{guid}";
+            var email = $"{guid}@example.com";
+
+            // Act & Assert
+            await UserStories.RegisterNewUserWithSocialLoginAsync(client, userName, email);
+
+            Assert.Equal("Contoso", authenticationMethod);
+        }
     }
 }