Added Guard.ThrowIfNull to throw ArgumentNullException, better than NRE

src/NLog.Extensions.Hosting/Extensions/ConfigureExtensions.cs

@@ -12,7 +12,7 @@
 namespace NLog.Extensions.Hosting
 {
     /// <summary>
-    ///     Helpers for IHostbuilder, netcore 2.1
+    ///     Helpers for IHostbuilder
     /// </summary>
     public static class ConfigureExtensions
     {
@@ -24,7 +24,7 @@ public static class ConfigureExtensions
         /// <returns>IHostBuilder for chaining</returns>
         public static IHostBuilder UseNLog(this IHostBuilder builder)
         {
-            if (builder == null) throw new ArgumentNullException(nameof(builder));
+            Guard.ThrowIfNull(builder);
             return builder.UseNLog(null);
         }
 
@@ -37,7 +37,7 @@ public static IHostBuilder UseNLog(this IHostBuilder builder)
         /// <returns>IHostBuilder for chaining</returns>
         public static IHostBuilder UseNLog(this IHostBuilder builder, NLogProviderOptions options)
         {
-            if (builder == null) throw new ArgumentNullException(nameof(builder));
+            Guard.ThrowIfNull(builder);
 #if NETSTANDARD2_0
             builder.ConfigureServices((builderContext, services) => AddNLogLoggerProvider(services, builderContext.Configuration, null, options, CreateNLogLoggerProvider));
 #else

src/NLog.Extensions.Hosting/NLog.Extensions.Hosting.csproj

@@ -49,6 +49,7 @@ Full changelog: https://github.com/NLog/NLog.Extensions.Logging/blob/master/CHAN
   </ItemGroup>
 
   <ItemGroup>
+    <Compile Include="..\NLog.Extensions.Logging\Internal\Guard.cs" Link="Internal\Guard.cs" />
     <Compile Include="..\NLog.Extensions.Logging\Internal\RegisterNLogLoggingProvider.cs" Link="Internal\RegisterNLogLoggingProvider.cs" />
   </ItemGroup>
 

src/NLog.Extensions.Logging/Config/NLogLoggingConfiguration.cs

@@ -55,7 +55,7 @@ public override IEnumerable<string> FileNamesToWatch
         {
             get
             {
-                if (_autoReload && _reloadConfiguration == null)
+                if (_autoReload && _reloadConfiguration is null)
                 {
                     // Prepare for setting up reload notification handling
                     _reloadConfiguration = state => ReloadConfigurationSection((IConfigurationSection)state);
@@ -229,7 +229,7 @@ private IEnumerable<ILoggingConfigurationElement> GetChildren()
                     }
                 }
 
-                if (ReferenceEquals(_nameOverride, VariableKey) && _configurationSection.Value == null)
+                if (ReferenceEquals(_nameOverride, VariableKey) && _configurationSection.Value is null)
                 {
                     yield return new LoggingConfigurationElement(_configurationSection);
                 }
@@ -255,7 +255,7 @@ private IEnumerable<ILoggingConfigurationElement> GetChildren(IEnumerable<IConfi
                     }
 
                     var firstChildValue = child?.GetChildren()?.FirstOrDefault();
-                    if (firstChildValue == null)
+                    if (firstChildValue is null)
                     {
                         continue; // Simple value without children
                     }
@@ -286,7 +286,7 @@ private static string GetConfigKey(IConfigurationSection child)
 
             private bool IsTargetsSection()
             {
-                return !_topElement && _nameOverride == null && GetConfigKey(_configurationSection).EqualsOrdinalIgnoreCase(TargetsKey);
+                return !_topElement && _nameOverride is null && GetConfigKey(_configurationSection).EqualsOrdinalIgnoreCase(TargetsKey);
             }
 
             /// <summary>

src/NLog.Extensions.Logging/Extensions/ConfigureExtensions.cs

@@ -41,6 +41,7 @@ public static ILoggerFactory AddNLog(this ILoggerFactory factory)
 #endif
         public static ILoggerFactory AddNLog(this ILoggerFactory factory, NLogProviderOptions options)
         {
+            Guard.ThrowIfNull(factory);
             factory.AddProvider(new NLogLoggerProvider(options));
             return factory;
         }
@@ -56,6 +57,7 @@ public static ILoggerFactory AddNLog(this ILoggerFactory factory, NLogProviderOp
 #endif
         public static ILoggerFactory AddNLog(this ILoggerFactory factory, IConfiguration configuration)
         {
+            Guard.ThrowIfNull(factory);
             var provider = CreateNLogLoggerProvider(null, configuration, null);
             factory.AddProvider(provider);
             return factory;
@@ -65,11 +67,11 @@ public static ILoggerFactory AddNLog(this ILoggerFactory factory, IConfiguration
         /// <summary>
         /// Enable NLog as logging provider for Microsoft Extension Logging
         /// </summary>
-        /// <param name="factory"></param>
+        /// <param name="builder"></param>
         /// <returns>ILoggingBuilder for chaining</returns>
-        public static ILoggingBuilder AddNLog(this ILoggingBuilder factory)
+        public static ILoggingBuilder AddNLog(this ILoggingBuilder builder)
         {
-            return factory.AddNLog((NLogProviderOptions)null);
+            return builder.AddNLog((NLogProviderOptions)null);
         }
 
         /// <summary>
@@ -80,33 +82,36 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder factory)
         /// <returns>ILoggingBuilder for chaining</returns>
         public static ILoggingBuilder AddNLog(this ILoggingBuilder factory, IConfiguration configuration)
         {
+            Guard.ThrowIfNull(factory);
             AddNLogLoggerProvider(factory, configuration, null, CreateNLogLoggerProvider);
             return factory;
         }
 
         /// <summary>
         /// Enable NLog as logging provider for Microsoft Extension Logging
         /// </summary>
-        /// <param name="factory"></param>
+        /// <param name="builder"></param>
         /// <param name="configuration">Override configuration and not use default Host Builder Configuration</param>
         /// <param name="options">NLog Logging Provider options</param>
         /// <returns>ILoggingBuilder for chaining</returns>
-        public static ILoggingBuilder AddNLog(this ILoggingBuilder factory, IConfiguration configuration, NLogProviderOptions options)
+        public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, IConfiguration configuration, NLogProviderOptions options)
         {
-            AddNLogLoggerProvider(factory, configuration, options, CreateNLogLoggerProvider);
-            return factory;
+            Guard.ThrowIfNull(builder);
+            AddNLogLoggerProvider(builder, configuration, options, CreateNLogLoggerProvider);
+            return builder;
         }
 
         /// <summary>
         /// Enable NLog as logging provider for Microsoft Extension Logging
         /// </summary>
-        /// <param name="factory"></param>
+        /// <param name="builder"></param>
         /// <param name="options">NLog Logging Provider options</param>
         /// <returns>ILoggingBuilder for chaining</returns>
-        public static ILoggingBuilder AddNLog(this ILoggingBuilder factory, NLogProviderOptions options)
+        public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, NLogProviderOptions options)
         {
-            AddNLogLoggerProvider(factory, null, options, CreateNLogLoggerProvider);
-            return factory;
+            Guard.ThrowIfNull(builder);
+            AddNLogLoggerProvider(builder, null, options, CreateNLogLoggerProvider);
+            return builder;
         }
 
         /// <summary>
@@ -129,6 +134,7 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, LoggingConfi
         /// <returns>ILoggingBuilder for chaining</returns>
         public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, LoggingConfiguration configuration, NLogProviderOptions options)
         {
+            Guard.ThrowIfNull(builder);
             AddNLogLoggerProvider(builder, null, options, (serviceProvider, config, options) =>
             {
                 var logFactory = configuration?.LogFactory ?? LogManager.LogFactory;
@@ -148,6 +154,7 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, LoggingConfi
         /// <returns>ILoggingBuilder for chaining</returns>
         public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, string configFileRelativePath)
         {
+            Guard.ThrowIfNull(builder);
             AddNLogLoggerProvider(builder, null, null, (serviceProvider, config, options) =>
             {
                 var provider = CreateNLogLoggerProvider(serviceProvider, config, options);
@@ -167,6 +174,8 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, string confi
         /// <returns>ILoggingBuilder for chaining</returns>
         public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, NLogProviderOptions options, Func<IServiceProvider, LogFactory> factoryBuilder)
         {
+            Guard.ThrowIfNull(builder);
+            Guard.ThrowIfNull(factoryBuilder);
             AddNLogLoggerProvider(builder, null, options, (serviceProvider, config, options) =>
             {
                 serviceProvider.SetupNLogConfigSettings(config, LogManager.LogFactory);
@@ -187,6 +196,8 @@ public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, NLogProvider
         /// <returns>ILoggingBuilder for chaining</returns>
         public static ILoggingBuilder AddNLog(this ILoggingBuilder builder, Func<IServiceProvider, LogFactory> factoryBuilder)
         {
+            Guard.ThrowIfNull(builder);
+            Guard.ThrowIfNull(factoryBuilder);
             AddNLogLoggerProvider(builder, null, null, (serviceProvider, config, options) =>
             {
                 serviceProvider.SetupNLogConfigSettings(config, LogManager.LogFactory);
@@ -240,7 +251,7 @@ public static LoggingConfiguration ConfigureNLog(this ILoggerFactory loggerFacto
         /// <returns></returns>
         public static NLogLoggerProvider Configure(this NLogLoggerProvider nlogProvider, IConfigurationSection configurationSection)
         {
-            if (nlogProvider == null || configurationSection == null)
+            if (nlogProvider is null || configurationSection is null)
                 return nlogProvider;
 
             Configure(nlogProvider.Options, configurationSection);
@@ -257,7 +268,7 @@ public static NLogProviderOptions Configure(this NLogProviderOptions options, IC
         {
             options = options ?? NLogProviderOptions.Default;
 
-            if (configurationSection == null || !(configurationSection.GetChildren()?.Any() ?? false))
+            if (configurationSection is null || !(configurationSection.GetChildren()?.Any() ?? false))
                 return options;
 
             var configProps = options.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public).Where(p => p.SetMethod?.IsPublic == true).ToDictionary(p => p.Name, StringComparer.OrdinalIgnoreCase);

src/NLog.Extensions.Logging/Internal/Guard.cs

@@ -0,0 +1,69 @@
+//
+// Copyright (c) 2004-2021 Jaroslaw Kowalski <jaak@jkowalski.net>, Kim Christensen, Julian Verdurmen
+//
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+//
+// * Neither the name of Jaroslaw Kowalski nor the names of its
+//   contributors may be used to endorse or promote products derived from this
+//   software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+// THE POSSIBILITY OF SUCH DAMAGE.
+//
+
+#if !NETCOREAPP3_1_OR_GREATER
+namespace System.Runtime.CompilerServices
+{
+    [AttributeUsage(AttributeTargets.Parameter)]
+    sealed class CallerArgumentExpressionAttribute : Attribute
+    {
+        public CallerArgumentExpressionAttribute(string param)
+        {
+            Param = param;
+        }
+
+        public string Param { get; }
+    }
+}
+#endif
+
+namespace NLog.Extensions.Logging
+{
+    using System;
+    using System.Runtime.CompilerServices;
+    internal static class Guard
+    {
+        internal static T ThrowIfNull<T>(
+            T arg,
+            [CallerArgumentExpression("arg")] string param = "")
+            where T : class
+        {
+            if (arg is null)
+            {
+                throw new ArgumentNullException(string.IsNullOrEmpty(param) ? typeof(T).Name : param);
+            }
+
+            return arg;
+        }
+    }
+}

src/NLog.Extensions.Logging/Internal/RegisterNLogLoggingProvider.cs

@@ -65,7 +65,7 @@ internal static NLogLoggerProvider CreateNLogLoggerProvider(this IServiceProvide
 
             var configuration = serviceProvider.SetupNLogConfigSettings(hostConfiguration, provider.LogFactory);
 
-            if (configuration != null && (!ReferenceEquals(configuration, hostConfiguration) || options == null))
+            if (configuration != null && (!ReferenceEquals(configuration, hostConfiguration) || options is null))
             {
                 provider.Configure(configuration.GetSection("Logging:NLog"));
             }

src/NLog.Extensions.Logging/Logging/NLogBeginScopeParser.cs

@@ -165,12 +165,12 @@ public static IDisposable CaptureScopeProperties(IEnumerable scopePropertyCollec
             var keyValueExtractor = default(KeyValuePair<Func<object, object>, Func<object, object>>);
             foreach (var property in scopePropertyCollection)
             {
-                if (property == null)
+                if (property is null)
                 {
                     break;
                 }
 
-                if (keyValueExtractor.Key == null && !TryLookupExtractor(stateExtractor, property.GetType(), out keyValueExtractor))
+                if (keyValueExtractor.Key is null && !TryLookupExtractor(stateExtractor, property.GetType(), out keyValueExtractor))
                 {
                     break;
                 }
@@ -257,7 +257,7 @@ private static bool TryBuildExtractor(Type propertyType, out KeyValuePair<Func<o
 
             var keyPropertyInfo = itemType.GetDeclaredProperty("Key");
             var valuePropertyInfo = itemType.GetDeclaredProperty("Value");
-            if (valuePropertyInfo == null || keyPropertyInfo == null)
+            if (valuePropertyInfo is null || keyPropertyInfo is null)
             {
                 return false;
             }

src/NLog.Extensions.Logging/Logging/NLogLogger.cs

@@ -35,7 +35,7 @@ public void Log<TState>(Microsoft.Extensions.Logging.LogLevel logLevel, EventId
                 return;
             }
 
-            if (formatter == null)
+            if (formatter is null)
             {
                 throw new ArgumentNullException(nameof(formatter));
             }
@@ -233,7 +233,7 @@ private static object[] CreatePositionalLogEventInfoParameters(NLogMessageParame
             for (int i = 0; i < messageParameterCount; ++i)
             {
                 // First positional name is the startPos
-                if (char.IsDigit(messageParameters[i].Name[0]) && paramsArray == null)
+                if (char.IsDigit(messageParameters[i].Name[0]) && paramsArray is null)
                 {
                     paramsArray = new object[maxIndex + 1];
                     for (int j = 0; j <= maxIndex; ++j)
@@ -457,7 +457,7 @@ private static LogLevel ConvertLogLevel(Microsoft.Extensions.Logging.LogLevel lo
         /// <returns></returns>
         public IDisposable BeginScope<TState>(TState state)
         {
-            if (!_options.IncludeScopes || state == null)
+            if (!_options.IncludeScopes || state is null)
             {
                 return NullScope.Instance;
             }

test/NLog.Extensions.Hosting.Tests/ExtensionMethodTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
@@ -10,6 +11,14 @@ namespace NLog.Extensions.Hosting.Tests
 {
     public class ExtensionMethodTests
     {
+        [Fact]
+        public void UseNLog_ArgumentNullException()
+        {
+            IHostBuilder hostBuilder = null;
+            var argNulLException = Assert.Throws<ArgumentNullException>(() => hostBuilder.UseNLog());
+            Assert.Equal("builder", argNulLException.ParamName);
+        }
+
         [Fact]
         public void UseNLog_noParams_WorksWithNLog()
         {

test/NLog.Extensions.Logging.Tests/CustomBeginScopeTest.cs

@@ -119,7 +119,7 @@ private class ActionLogScope : IReadOnlyList<KeyValuePair<string, object>>
 
             public ActionLogScope(string world)
             {
-                if (world == null)
+                if (world is null)
                 {
                     throw new ArgumentNullException(nameof(world));
                 }

test/NLog.Extensions.Logging.Tests/Extensions/ConfigureExtensionsTests.cs

@@ -158,6 +158,14 @@ public void AddNLog_ReplaceLoggerFactory()
             Assert.Equal(typeof(NLogLoggerProvider), loggerProvider.GetType());
         }
 
+        [Fact]
+        public void AddNLog_ArgumentNullException()
+        {
+            ILoggingBuilder loggingBuilder = null;
+            var argNulLException = Assert.Throws<ArgumentNullException>(() => loggingBuilder.AddNLog());
+            Assert.Equal("builder", argNulLException.ParamName);
+        }
+
         [Fact]
         public void AddNLog_WithConfig_ReplaceLoggerFactory()
         {

test/NLog.Extensions.Logging.Tests/NLogTestBase.cs

@@ -11,7 +11,7 @@ public abstract class NLogTestBase
 
         protected NLogLoggerProvider ConfigureLoggerProvider(NLogProviderOptions options = null, Action<ServiceCollection> configureServices = null)
         {
-            if (_serviceProvider == null)
+            if (_serviceProvider is null)
             {
                 var logFactory = new LogFactory();
                 LoggerProvider = new NLogLoggerProvider(options ?? new NLogProviderOptions { CaptureMessageTemplates = true, CaptureMessageProperties = true }, logFactory);
@@ -28,7 +28,7 @@ protected NLogLoggerProvider ConfigureLoggerProvider(NLogProviderOptions options
 
         protected IServiceProvider ConfigureTransientService<T>(Action<ServiceCollection> configureServices = null, NLogProviderOptions options = null) where T : class
         {
-            if (_serviceProvider == null)
+            if (_serviceProvider is null)
                 ConfigureLoggerProvider(options, s => { s.AddTransient<T>(); configureServices?.Invoke(s); });
             return _serviceProvider;
         }