From 6190ca819f3f3a63faa282170f48e23ebf82d37c Mon Sep 17 00:00:00 2001
From: Nicholas Blumhardt <nblumhardt@nblumhardt.com>
Date: Sun, 28 May 2017 08:36:01 +1000
Subject: [PATCH] #773 - clone and re-import LogContext.

---
 src/Serilog/Context/LogContext.cs             | 31 +++++++++----------
 test/Serilog.Tests/Context/LogContextTests.cs | 24 ++++++++++++++
 2 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/src/Serilog/Context/LogContext.cs b/src/Serilog/Context/LogContext.cs
index 0b9723ad9..accfe9da0 100644
--- a/src/Serilog/Context/LogContext.cs
+++ b/src/Serilog/Context/LogContext.cs
@@ -139,6 +139,17 @@ public static IDisposable PushProperties(params ILogEventEnricher[] properties)
             return Push(properties);
         }
 
+        /// <summary>
+        /// Obtain an enricher that represents the current contents of the <see cref="LogContext"/>. This
+        /// can be pushed back onto the context in a different location/thread when required.
+        /// </summary>
+        /// <returns>An enricher that represents the current contents of the <see cref="LogContext"/>.</returns>
+        public static ILogEventEnricher Clone()
+        {
+            var stack = GetOrCreateEnricherStack();
+            return new SafeAggregateEnricher(stack);
+        }
+
         static ImmutableStack<ILogEventEnricher> GetOrCreateEnricherStack()
         {
             var enrichers = Enrichers;
@@ -181,14 +192,8 @@ public void Dispose()
 
         static ImmutableStack<ILogEventEnricher> Enrichers
         {
-            get
-            {
-                return Data.Value;
-            }
-            set
-            {
-                Data.Value = value;
-            }
+            get => Data.Value;
+            set => Data.Value = value;
         }
 
 #elif REMOTING
@@ -211,14 +216,8 @@ static ImmutableStack<ILogEventEnricher> Enrichers
 
         static ImmutableStack<ILogEventEnricher> Enrichers
         {
-            get
-            {
-                return Data;
-            }
-            set
-            {
-                Data = value;
-            }
+            get => Data;
+            set => Data = value;
         }
 #endif
     }
diff --git a/test/Serilog.Tests/Context/LogContextTests.cs b/test/Serilog.Tests/Context/LogContextTests.cs
index f2c184e29..a6bf641ac 100644
--- a/test/Serilog.Tests/Context/LogContextTests.cs
+++ b/test/Serilog.Tests/Context/LogContextTests.cs
@@ -12,6 +12,7 @@
 #endif
 using System.Threading;
 using System.Threading.Tasks;
+using Serilog.Core;
 
 namespace Serilog.Tests.Context
 {
@@ -46,6 +47,29 @@ public void PushedPropertiesAreAvailableToLoggers()
             }
         }
 
+        [Fact]
+        public void LogContextCanBeCloned()
+        {
+            LogEvent lastEvent = null;
+
+            var log = new LoggerConfiguration()
+                .Enrich.FromLogContext()
+                .WriteTo.Sink(new DelegatingSink(e => lastEvent = e))
+                .CreateLogger();
+
+            ILogEventEnricher clonedContext;
+            using (LogContext.PushProperty("A", 1))
+            {
+                clonedContext = LogContext.Clone();
+            }
+
+            using (LogContext.Push(clonedContext))
+            {
+                log.Write(Some.InformationEvent());
+                Assert.Equal(1, lastEvent.Properties["A"].LiteralValue());
+            }
+        }
+
         [Fact]
         public void MoreNestedPropertiesOverrideLessNestedOnes()
         {