Updated test logic to report exceptions gracefully.

src/NzbDrone.Core/Download/Clients/DownloadClientException.cs

@@ -1,14 +1,30 @@
-using NzbDrone.Common.Exceptions;
+using System;
+using NzbDrone.Common.Exceptions;
 
 namespace NzbDrone.Core.Download.Clients
 {
     public class DownloadClientException : NzbDroneException
     {
-        public DownloadClientException(string message, params object[] args) : base(message, args)
+        public DownloadClientException(string message, params object[] args)
+            : base(string.Format(message, args))
         {
+
         }
 
-        public DownloadClientException(string message) : base(message)
+        public DownloadClientException(string message)
+            : base(message)
+        {
+
+        }
+
+        public DownloadClientException(string message, Exception innerException, params object[] args)
+            : base(string.Format(message, args), innerException)
+        {
+
+        }
+
+        public DownloadClientException(string message, Exception innerException)
+            : base(message, innerException)
         {
         }
     }

src/NzbDrone.Core/Download/Clients/Nzbget/Nzbget.cs

@@ -11,6 +11,7 @@ using NzbDrone.Core.Configuration;
 using NzbDrone.Core.Indexers;
 using NzbDrone.Core.Parser;
 using NzbDrone.Core.Parser.Model;
+using NzbDrone.Core.Validation;
 
 namespace NzbDrone.Core.Download.Clients.Nzbget
 {
@@ -290,10 +291,8 @@ namespace NzbDrone.Core.Download.Clients.Nzbget
             }
         }
 
-        public override ValidationResult Test()
+        protected override void Test(List<ValidationFailure> failures)
         {
-            var failures = new List<ValidationFailure>();
-
             failures.AddIfNotNull(TestConnection());
             failures.AddIfNotNull(TestCategory());
 
@@ -301,8 +300,6 @@ namespace NzbDrone.Core.Download.Clients.Nzbget
             {
                 failures.AddIfNotNull(TestFolder(Settings.TvCategoryLocalPath, "TvCategoryLocalPath"));
             }
-
-            return new ValidationResult(failures);
         }
 
         private ValidationFailure TestConnection()
@@ -313,6 +310,10 @@ namespace NzbDrone.Core.Download.Clients.Nzbget
             }
             catch (Exception ex)
             {
+                if (ex.Message.ContainsIgnoreCase("Authentication failed"))
+                {
+                    return new ValidationFailure("Username", "Authentication failed");
+                }
                 _logger.ErrorException(ex.Message, ex);
                 return new ValidationFailure("Host", "Unable to connect to NZBGet");
             }
@@ -327,7 +328,11 @@ namespace NzbDrone.Core.Download.Clients.Nzbget
 
             if (!Settings.TvCategory.IsNullOrWhiteSpace() && !categories.Any(v => v.Name == Settings.TvCategory))
             {
-                return new ValidationFailure("TvCategory", "Category does not exist");
+                return new NzbDroneValidationFailure("TvCategory", "Category does not exist")
+                {
+                    InfoLink = String.Format("http://{0}:{1}/", Settings.Host, Settings.Port),
+                    DetailedDescription = "The Category your entered doesn't exist in NzbGet. Go to NzbGet to create it."
+                };
             }
 
             return null;

src/NzbDrone.Core/Download/Clients/Nzbget/NzbgetProxy.cs

@@ -193,7 +193,12 @@ namespace NzbDrone.Core.Download.Clients.Nzbget
         {
             if (response.ResponseStatus != ResponseStatus.Completed)
             {
-                throw new DownloadClientException("Unable to connect to NzbGet, please check your settings");
+                throw new DownloadClientException("Unable to connect to NzbGet, please check your settings", response.ErrorException);
+            }
+
+            if (response.StatusCode == System.Net.HttpStatusCode.Unauthorized)
+            {
+                throw new DownloadClientException("Authentication failed for NzbGet, please check your settings", response.ErrorException);
             }
 
             var result = Json.Deserialize<JsonError>(response.Content);

src/NzbDrone.Core/Download/Clients/Pneumatic/Pneumatic.cs

@@ -95,13 +95,9 @@ namespace NzbDrone.Core.Download.Clients.Pneumatic
             return status;
         }
 
-        public override ValidationResult Test()
+        protected override void Test(List<ValidationFailure> failures)
         {
-            var failures = new List<ValidationFailure>();
-
             failures.AddIfNotNull(TestWrite(Settings.NzbFolder, "NzbFolder"));
-
-            return new ValidationResult(failures);
         }
 
         private ValidationFailure TestWrite(String folder, String propertyName)

src/NzbDrone.Core/Download/Clients/Sabnzbd/Sabnzbd.cs

@@ -303,19 +303,16 @@ namespace NzbDrone.Core.Download.Clients.Sabnzbd
             return status;
         }
 
-        public override ValidationResult Test()
+        protected override void Test(List<ValidationFailure> failures)
         {
-            var failures = new List<ValidationFailure>();
-
             failures.AddIfNotNull(TestConnection());
+            failures.AddIfNotNull(TestAuthentication());
             failures.AddIfNotNull(TestCategory());
 
             if (!Settings.TvCategoryLocalPath.IsNullOrWhiteSpace())
             {
                 failures.AddIfNotNull(TestFolder(Settings.TvCategoryLocalPath, "TvCategoryLocalPath"));
             }
-
-            return new ValidationResult(failures);
         }
 
         private ValidationFailure TestConnection()
@@ -333,6 +330,28 @@ namespace NzbDrone.Core.Download.Clients.Sabnzbd
             return null;
         }
 
+        private ValidationFailure TestAuthentication()
+        {
+            try
+            {
+                _proxy.GetConfig(Settings);
+            }
+            catch (Exception ex)
+            {
+                if (ex.Message.ContainsIgnoreCase("API Key Incorrect"))
+                {
+                    return new ValidationFailure("APIKey", "API Key Incorrect");
+                }
+                if (ex.Message.ContainsIgnoreCase("API Key Required"))
+                {
+                    return new ValidationFailure("APIKey", "API Key Required");
+                }
+                throw;
+            }
+
+            return null;
+        }
+
         private ValidationFailure TestCategory()
         {
             var config = this._proxy.GetConfig(Settings);

src/NzbDrone.Core/Download/Clients/Sabnzbd/SabnzbdProxy.cs

@@ -145,7 +145,7 @@ namespace NzbDrone.Core.Download.Clients.Sabnzbd
         {
             if (response.ResponseStatus != ResponseStatus.Completed)
             {
-                throw new DownloadClientException("Unable to connect to SABnzbd, please check your settings");
+                throw new DownloadClientException("Unable to connect to SABnzbd, please check your settings", response.ErrorException);
             }
 
             SabnzbdJsonError result;

src/NzbDrone.Core/Download/Clients/UsenetBlackhole/UsenetBlackhole.cs

@@ -143,14 +143,10 @@ namespace NzbDrone.Core.Download.Clients.UsenetBlackhole
             };
         }
 
-        public override ValidationResult Test()
+        protected override void Test(List<ValidationFailure> failures)
         {
-            var failures = new List<ValidationFailure>();
-
             failures.AddIfNotNull(TestFolder(Settings.NzbFolder, "NzbFolder"));
             failures.AddIfNotNull(TestFolder(Settings.WatchFolder, "WatchFolder"));
-
-            return new ValidationResult(failures);
         }
     }
 }

src/NzbDrone.Core/Download/DownloadClientBase.cs

@@ -11,6 +11,7 @@ using NzbDrone.Core.ThingiProvider;
 using NzbDrone.Core.Configuration;
 using NLog;
 using FluentValidation.Results;
+using NzbDrone.Core.Validation;
 
 namespace NzbDrone.Core.Download
 {
@@ -39,7 +40,6 @@ namespace NzbDrone.Core.Download
         }
 
         public ProviderDefinition Definition { get; set; }
-        public abstract ValidationResult Test();
 
         protected TSettings Settings
         {
@@ -101,11 +101,33 @@ namespace NzbDrone.Core.Download
             }
         }
 
+        public ValidationResult Test()
+        {
+            var failures = new List<ValidationFailure>();
+            
+            try
+            {
+                Test(failures);
+            }
+            catch (Exception ex)
+            {
+                _logger.ErrorException("Test aborted due to exception", ex);
+                failures.Add(new ValidationFailure(string.Empty, "Test was aborted due to an error: " + ex.Message));
+            }
+
+            return new ValidationResult(failures);
+        }
+
+        protected abstract void Test(List<ValidationFailure> failures);
+
         protected ValidationFailure TestFolder(String folder, String propertyName, Boolean mustBeWritable = true)
         {
             if (!_diskProvider.FolderExists(folder))
             {
-                return new ValidationFailure(propertyName, "Folder does not exist");
+                return new NzbDroneValidationFailure(propertyName, "Folder does not exist")
+                {
+                    DetailedDescription = "The folder you specified does not exist or is inaccessible. Please verify the folder permissions for the user account that is used to execute NzbDrone."
+                };
             }
 
             if (mustBeWritable)
@@ -119,7 +141,10 @@ namespace NzbDrone.Core.Download
                 catch (Exception ex)
                 {
                     _logger.ErrorException(ex.Message, ex);
-                    return new ValidationFailure(propertyName, "Unable to write to folder");
+                    return new NzbDroneValidationFailure(propertyName, "Unable to write to folder")
+                    {
+                        DetailedDescription = "The folder you specified is not writable. Please verify the folder permissions for the user account that is used to execute NzbDrone."
+                    };
                 }
             }