Add LogLevel availability check to IMvxLog

MvvmCross/Core/Core/Platform/LogProviders/MvxLog.cs

@@ -14,6 +14,8 @@ namespace MvvmCross.Core.Platform.LogProviders
             _logger = logger;
         }
 
+        public bool IsLogLevelEnabled(MvxLogLevel logLevel) => _logger(logLevel, null);
+
         public bool Log(MvxLogLevel logLevel, Func<string> messageFunc, Exception exception = null, params object[] formatParameters)
         {
             if (messageFunc == null)

MvvmCross/Platform/Platform/Logging/IMvxLog.cs

@@ -5,5 +5,7 @@ namespace MvvmCross.Platform.Logging
     public interface IMvxLog
     {
         bool Log(MvxLogLevel logLevel, Func<string> messageFunc, Exception exception = null, params object[] formatParameters);
+
+        bool IsLogLevelEnabled(MvxLogLevel logLevel);
     }
 }

MvvmCross/Platform/Platform/Logging/MvxLogExtensions.cs

@@ -7,37 +7,37 @@ namespace MvvmCross.Platform.Logging
         public static bool IsDebugEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Debug, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Debug);
         }
 
         public static bool IsErrorEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Error, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Error);
         }
 
         public static bool IsFatalEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Fatal, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Fatal);
         }
 
         public static bool IsInfoEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Info, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Info);
         }
 
         public static bool IsTraceEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Trace, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Trace);
         }
 
         public static bool IsWarnEnabled(this IMvxLog logger)
         {
             GuardAgainstNullLogger(logger);
-            return logger.Log(MvxLogLevel.Warn, null);
+            return logger.IsLogLevelEnabled(MvxLogLevel.Warn);
         }
 
         public static void Debug(this IMvxLog logger, Func<string> messageFunc)
@@ -292,7 +292,7 @@ namespace MvvmCross.Platform.Logging
         {
             if (logger == null)
             {
-                throw new ArgumentNullException("logger");
+                throw new ArgumentNullException(nameof(logger));
             }
         }