feat: add custom claim enricher

src/Serilog.Enrichers.AzureClaims/Enrichers/CustomClaimEnricher.cs

@@ -0,0 +1,41 @@
+using Microsoft.AspNetCore.Http;
+using System.Security.Claims;
+
+namespace Serilog.Enrichers.AzureClaims;
+
+/// <summary>
+/// Enriches log events with a custom property from the user's claims.
+/// </summary>
+internal class CustomClaimEnricher : BaseEnricher
+{
+    private readonly string _customClaimType;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CustomClaimEnricher"/> class.
+    /// </summary>
+    public CustomClaimEnricher(string claimType, string? customPropertyName = null) : base($"Serilog_{customPropertyName ?? claimType}", customPropertyName ?? claimType)
+    {
+        _customClaimType = claimType;
+    }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="CustomClaimEnricher"/> class with the specified HTTP context accessor.
+    /// </summary>
+    /// <param name="contextAccessor">The HTTP context accessor to use for retrieving the user's claims.</param>
+    /// <param name="claimType">The custom claimType to be used to find the claim</param>
+    /// <param name="customPropertyName">The custom property name to be used in the enriched logs.</param>
+    internal CustomClaimEnricher(IHttpContextAccessor contextAccessor, string claimType, string? customPropertyName = null) : base(contextAccessor, $"Serilog_{customPropertyName ?? claimType}", customPropertyName ?? claimType)
+    {
+        _customClaimType = claimType;
+    }
+
+    /// <summary>
+    /// Gets the Custom Claim property value from the specified claims principal.
+    /// </summary>
+    /// <param name="user">The claims principal representing the user.</param>
+    /// <returns>The Custom Claim property value, or <c>null</c> if it cannot be found.</returns>
+    protected override string? GetPropertyValue(ClaimsPrincipal user)
+    {
+        return user.FindFirstValue(_customClaimType);
+    }
+}

src/Serilog.Enrichers.AzureClaims/Extensions/AuthenticationInformationLoggerConfigurationExtensions.cs

@@ -73,4 +73,28 @@ public static LoggerConfiguration WithAppId(this LoggerEnrichmentConfiguration e
 
         return enrichmentConfiguration.With<AppIdEnricher>();
     }
+
+    /// <summary>
+    /// Adds a custom claim enrichment to the logger configuration.
+    /// </summary>
+    /// <param name="enrichmentConfiguration">The logger enrichment configuration.</param>
+    /// <param name="claimType">The type of the claim to be used for enrichment.</param>
+    /// <param name="propertyName">The name visible in the enriched logs</param>
+    /// <returns>The logger configuration with the custom claim enrichment added.</returns>
+    /// <exception cref="ArgumentNullException">Thrown when <paramref name="enrichmentConfiguration"/> or <paramref name="claimType"/> is null.</exception>
+    public static LoggerConfiguration WithCustomClaim(this LoggerEnrichmentConfiguration enrichmentConfiguration, string claimType, string? propertyName = null)
+    {
+        ArgumentNullException.ThrowIfNull(enrichmentConfiguration, nameof(enrichmentConfiguration));
+
+#if (NET6_0)
+        if (string.IsNullOrWhiteSpace(claimType))
+        {
+            throw new ArgumentNullException(nameof(claimType));
+        }
+#else
+        ArgumentNullException.ThrowIfNullOrEmpty(claimType, nameof(claimType));
+#endif
+
+        return enrichmentConfiguration.With(new CustomClaimEnricher(claimType, propertyName));
+    }
 }

tests/Serilog.Enrichers.AzureClaims.Tests/CustomClaimEnricherTests.cs

@@ -0,0 +1,96 @@
+using Microsoft.AspNetCore.Http;
+using NSubstitute;
+using Serilog.Enrichers.AzureClaims.Tests.Helpers;
+using Serilog.Events;
+using System.Security.Claims;
+using Xunit;
+
+namespace Serilog.Enrichers.AzureClaims.Tests
+{
+    public class CustomClaimEnricherTests
+    {
+        private const string _customClaimType = "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress";
+        private const string _customClaimPropertyName = "Email";
+
+        [Fact]
+        public void LogEvent_DoesNotContainCustomClaimWhenUserIsNotLoggedIn()
+        {
+            // Arrange
+            var httpContextAccessorMock = Substitute.For<IHttpContextAccessor>();
+            httpContextAccessorMock.HttpContext.Returns(new DefaultHttpContext());
+
+            var CustomClaimEnricher = new CustomClaimEnricher(httpContextAccessorMock, _customClaimType, _customClaimPropertyName);
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.With(CustomClaimEnricher)
+                .WriteTo.Sink(new DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            // Act
+            log.Information(@"Email property is not set when the user is not logged in");
+
+            // Assert
+            Assert.NotNull(evt);
+            Assert.False(evt.Properties.ContainsKey("Email"));
+        }
+
+        [Fact]
+        public void LogEvent_ContainsUnknownCustomClaimWhenUserIsLoggedInButCustomClaimIsNotFound()
+        {
+            // Arrange
+            var httpContextAccessorMock = Substitute.For<IHttpContextAccessor>();
+            var user = new ClaimsPrincipal(TestClaimsProvider.NotValidClaims().GetClaimsPrincipal());
+
+            httpContextAccessorMock.HttpContext.Returns(new DefaultHttpContext
+            {
+                User = user
+            });
+
+            var CustomClaimEnricher = new CustomClaimEnricher(httpContextAccessorMock, _customClaimType, _customClaimPropertyName);
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.With(CustomClaimEnricher)
+                .WriteTo.Sink(new DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            // Act
+            log.Information(@"Email property is set to unknown when the user is logged in");
+
+            // Assert
+            Assert.NotNull(evt);
+            Assert.True(evt.Properties.ContainsKey("Email"));
+            Assert.Equal("unknown", evt.Properties["Email"].LiteralValue().ToString());
+        }
+
+        [Fact]
+        public void LogEvent_ContainCustomClaimWhenUserIsLoggedIn()
+        {
+            // Arrange
+            var httpContextAccessorMock = Substitute.For<IHttpContextAccessor>();
+            var user = new ClaimsPrincipal(TestClaimsProvider.ValidClaims().GetClaimsPrincipal());
+
+            httpContextAccessorMock.HttpContext.Returns(new DefaultHttpContext
+            {
+                User = user
+            });
+
+            var CustomClaimEnricher = new CustomClaimEnricher(httpContextAccessorMock, _customClaimType, _customClaimPropertyName);
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.With(CustomClaimEnricher)
+                .WriteTo.Sink(new DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            // Act
+            log.Information(@"Email property is set when the user is logged in");
+
+            // Assert
+            Assert.NotNull(evt);
+            Assert.True(evt.Properties.ContainsKey("Email"));
+            Assert.Equal(TestConstants.EMAIL, evt.Properties["Email"].LiteralValue().ToString());
+        }
+    }
+}

tests/Serilog.Enrichers.AzureClaims.Tests/Extensions/ExtensionsBindingTests.cs

@@ -25,6 +25,7 @@ public void AllEnrichers_AreAddedToTheBuilder()
                 .Enrich.WithTenantId()
                 .Enrich.WithObjectId()
                 .Enrich.WithDisplayName()
+                .Enrich.WithCustomClaim("test")
                 .WriteTo.Sink(new DelegatingSink(e => evt = e))
                 .CreateLogger();
 
@@ -43,7 +44,8 @@ public void AllEnrichers_AreAddedToTheBuilder()
                 item => Assert.Equal(nameof(AppIdEnricher), item.GetType().Name),
                 item => Assert.Equal(nameof(TenantIdEnricher), item.GetType().Name),
                 item => Assert.Equal(nameof(ObjectIdEnricher), item.GetType().Name),
-                item => Assert.Equal(nameof(DisplayNameEnricher), item.GetType().Name));
+                item => Assert.Equal(nameof(DisplayNameEnricher), item.GetType().Name),
+                item => Assert.Equal(nameof(CustomClaimEnricher), item.GetType().Name));
         }
 
         // Method to count the number of enrichers in the project. Ignores the base enricher
@@ -167,5 +169,27 @@ public void OIDEnricher_IsAddedToTheBuilder()
 
             Assert.Equal(nameof(ObjectIdEnricher), enricher.Name);
         }
+
+        [Fact]
+        public void CustomClaimEnricher_IsAddedToTheBuilder()
+        {
+            // Arrange
+            var httpContextAccessorMock = Substitute.For<IHttpContextAccessor>();
+            httpContextAccessorMock.HttpContext.Returns(new DefaultHttpContext());
+
+            LogEvent evt = null;
+            var log = new LoggerConfiguration()
+                .Enrich.WithCustomClaim("test")
+                .WriteTo.Sink(new DelegatingSink(e => evt = e))
+                .CreateLogger();
+
+            var aggregateEnricherFieldInfo = log.GetType()
+                .GetField("_enricher", BindingFlags.Instance | BindingFlags.NonPublic);
+
+            var aggregateEnricher = aggregateEnricherFieldInfo?.GetValue(log);
+            var enricher = aggregateEnricher.GetType();
+
+            Assert.Equal(nameof(CustomClaimEnricher), enricher.Name);
+        }
     }
 }

tests/Serilog.Enrichers.AzureClaims.Tests/Helpers/TestClaimsProvider.cs

@@ -5,7 +5,7 @@ namespace Serilog.Enrichers.AzureClaims.Tests.Helpers
 {
     public class TestClaimsProvider
     {
-        private List<Claim> Claims { get; } = new List<Claim>();
+        private List<Claim> Claims { get; } = [];
 
         public ClaimsPrincipal GetClaimsPrincipal()
         {
@@ -30,7 +30,8 @@ public static TestClaimsProvider ValidClaims()
                 .AddClaim(ClaimTypes.Name, TestConstants.NAME)
                 .AddClaim(ClaimConstants.ObjectId, TestConstants.OID)
                 .AddClaim(ClaimTypes.Upn, TestConstants.UPN)
-                .AddClaim(ClaimConstants.Tid, TestConstants.TENANTID);
+                .AddClaim(ClaimConstants.Tid, TestConstants.TENANTID)
+                .AddClaim(ClaimTypes.Email, TestConstants.EMAIL);
         }
     }
 }

tests/Serilog.Enrichers.AzureClaims.Tests/Helpers/TestConstants.cs

@@ -7,6 +7,7 @@ public static class TestConstants
         public static string OID = "0f1eddfd-cec1-4444-88f3-07476b7e69ee";
         public static string UPN = "[email protected]";
         public static string TENANTID = "79ce530d-c819-40ed-9a25-eebabd34edfe";
+        public static string EMAIL = "[email protected]";
 #pragma warning restore CA2211 // Non-constant fields should not be visible
     }
 }