Avoid NullReferenceException in Logger by null-guarding the loggers in SetLoggers().

Author: asbjornu

src/GitVersionCore/Logger.cs

@@ -9,16 +9,18 @@ public static class Logger
         static readonly Regex ObscurePasswordRegex = new Regex("(https?://)(.+)(:.+@)", RegexOptions.Compiled);
         static string indent = string.Empty;
 
-        public static Action<string> WriteInfo { get; private set; }
-        public static Action<string> WriteWarning { get; private set; }
-        public static Action<string> WriteError { get; private set; }
-
 
         static Logger()
         {
             Reset();
         }
 
+
+        public static Action<string> WriteInfo { get; private set; }
+        public static Action<string> WriteWarning { get; private set; }
+        public static Action<string> WriteError { get; private set; }
+
+
         public static IDisposable IndentLog(string operationDescription)
         {
             var start = DateTime.Now;
@@ -31,6 +33,7 @@ public static IDisposable IndentLog(string operationDescription)
             });
         }
 
+
         static Action<string> ObscurePassword(Action<string> info)
         {
             Action<string> logAction = s =>
@@ -41,34 +44,55 @@ static Action<string> ObscurePassword(Action<string> info)
             return logAction;
         }
 
+
         public static void SetLoggers(Action<string> info, Action<string> warn, Action<string> error)
         {
+            if (info == null)
+            {
+                throw new ArgumentNullException("info");
+            }
+
+            if (warn == null)
+            {
+                throw new ArgumentNullException("warn");
+            }
+
+            if (error == null)
+            {
+                throw new ArgumentNullException("error");
+            }
+
             WriteInfo = LogMessage(ObscurePassword(info), "INFO");
             WriteWarning = LogMessage(ObscurePassword(warn), "WARN");
             WriteError = LogMessage(ObscurePassword(error), "ERROR");
         }
 
+
         static Action<string> LogMessage(Action<string> logAction, string level)
         {
             return s => logAction(string.Format(CultureInfo.InvariantCulture, "{0}{1} [{2:MM/dd/yy H:mm:ss:ff}] {3}", indent, level, DateTime.Now, s));
         }
 
+
         public static void Reset()
         {
             WriteInfo = s => { throw new Exception("Logger not defined."); };
             WriteWarning = s => { throw new Exception("Logger not defined."); };
             WriteError = s => { throw new Exception("Logger not defined."); };
         }
 
+
         class ActionDisposable : IDisposable
         {
             readonly Action action;
 
+
             public ActionDisposable(Action action)
             {
                 this.action = action;
             }
 
+
             public void Dispose()
             {
                 action();