small fixes

StackExchange.Redis.Tests/TestBase.cs

@@ -243,7 +243,7 @@ private static RedisConnection GetOldStyleConnection(string host, int port, bool
         protected static TimeSpan RunConcurrent(Action work, int threads, int timeout = 10000, [CallerMemberName] string caller = null)
         {
             if (work == null) throw new ArgumentNullException("work");
-            if (threads < 1) throw new ArgumentOutOfRangeException("theads");
+            if (threads < 1) throw new ArgumentOutOfRangeException("threads");
             if(string.IsNullOrWhiteSpace(caller)) caller = Me();
             Stopwatch watch = null;
             ManualResetEvent allDone = new ManualResetEvent(false);

StackExchange.Redis/StackExchange/Redis/Format.cs

@@ -133,7 +133,7 @@ internal static bool TryGetHostPort(EndPoint endpoint, out string host, out int
 
         internal static bool TryParseDouble(string s, out double value)
         {
-            if(s == null || s.Length == 0)
+            if(string.IsNullOrEmpty(s))
             {
                 value = 0;
                 return false;

StackExchange.Redis/StackExchange/Redis/RedisDatabase.cs

@@ -484,7 +484,7 @@ sealed class KeyMigrateCommandMessage : Message.CommandKeyBase // MIGRATE is aty
             public KeyMigrateCommandMessage(int db, RedisKey key, EndPoint toServer, int toDatabase, int timeoutMilliseconds, MigrateOptions migrateOptions, CommandFlags flags)
                 : base(db, flags, RedisCommand.MIGRATE, key)
             {
-                if (toServer == null) throw new ArgumentNullException("server");
+                if (toServer == null) throw new ArgumentNullException("toServer");
                 string toHost;
                 int toPort;
                 if (!Format.TryGetHostPort(toServer, out toHost, out toPort)) throw new ArgumentException("toServer");