Fixed: InvalidOperationException when two artists have same name

src/NzbDrone.Core.Test/MusicTests/ArtistRepositoryTests/ArtistRepositoryFixture.cs

@@ -19,6 +19,7 @@ namespace NzbDrone.Core.Test.MusicTests.ArtistRepositoryTests
     {
         private ArtistRepository _artistRepo;
         private ArtistMetadataRepository _artistMetadataRepo;
+        private int _id = 1;
 
         private void AddArtist(string name)
         {
@@ -31,8 +32,9 @@ namespace NzbDrone.Core.Test.MusicTests.ArtistRepositoryTests
                 .With(a => a.Id = 0)
                 .With(a => a.Metadata = metadata)
                 .With(a => a.CleanName = Parser.Parser.CleanArtistName(name))
-                .With(a => a.ForeignArtistId = name)
+                .With(a => a.ForeignArtistId = _id.ToString())
                 .BuildNew();
+            _id++;
 
             _artistMetadataRepo.Insert(artist);
             _artistRepo.Insert(artist);
@@ -101,5 +103,20 @@ namespace NzbDrone.Core.Test.MusicTests.ArtistRepositoryTests
             artist.Should().NotBeNull();
             artist.Name.Should().Be(name);
         }
+
+        [Test]
+        public void should_not_find_artist_if_multiple_artists_have_same_name()
+        {
+            GivenArtists();
+
+            string name = "Alice Cooper";
+            AddArtist(name);
+            AddArtist(name);
+
+            _artistRepo.All().Should().HaveCount(4);
+            
+            var artist = _artistRepo.FindByName(Parser.Parser.CleanArtistName(name));
+            artist.Should().BeNull();
+        }
     }
 }

src/NzbDrone.Core/Music/ArtistRepository.cs

@@ -2,6 +2,7 @@
 using NzbDrone.Core.Datastore;
 using NzbDrone.Core.Messaging.Events;
 using Marr.Data.QGen;
+using NzbDrone.Common.Extensions;
 
 namespace NzbDrone.Core.Music
 {
@@ -43,8 +44,7 @@ namespace NzbDrone.Core.Music
         {
             cleanName = cleanName.ToLowerInvariant();
 
-            return Query.Where(s => s.CleanName == cleanName)
-                        .SingleOrDefault();
+            return Query.Where(s => s.CleanName == cleanName).ExclusiveOrDefault();
         }
 
         public Artist GetArtistByMetadataId(int artistMetadataId)