Merge pull request #7078 from 1337joe/metadata-merge-data

2 files changed, 497 insertions, 70 deletions

diff --git a/tests/Jellyfin.Providers.Tests/Manager/ItemImageProviderTests.cs b/tests/Jellyfin.Providers.Tests/Manager/ItemImageProviderTests.cs
index 2ba5c47d7..c0931dbcf 100644
--- a/tests/Jellyfin.Providers.Tests/Manager/ItemImageProviderTests.cs
+++ b/tests/Jellyfin.Providers.Tests/Manager/ItemImageProviderTests.cs
@@ -41,10 +41,7 @@ namespace Jellyfin.Providers.Tests.Manager
         [Fact]
         public void ValidateImages_EmptyItemEmptyProviders_NoChange()
         {
-            var itemImageProvider = GetItemImageProvider(null, null);
-            var changed = itemImageProvider.ValidateImages(new Video(), Enumerable.Empty<ILocalImageProvider>(), null);
-
-            Assert.False(changed);
+            ValidateImages_Test(ImageType.Primary, 0, true, 0, false, 0);
         }
 
         private static TheoryData<ImageType, int> GetImageTypesWithCount()
@@ -53,7 +50,6 @@ namespace Jellyfin.Providers.Tests.Manager
             {
                 // minimal test cases that hit different handling
                 { ImageType.Primary, 1 },
-                { ImageType.Backdrop, 1 },
                 { ImageType.Backdrop, 2 }
             };
 
@@ -64,43 +60,34 @@ namespace Jellyfin.Providers.Tests.Manager
         [MemberData(nameof(GetImageTypesWithCount))]
         public void ValidateImages_EmptyItemAndPopulatedProviders_AddsImages(ImageType imageType, int imageCount)
         {
-            // Has to exist for querying DateModified time on file, results stored but not checked so not populating
-            BaseItem.FileSystem = Mock.Of<IFileSystem>();
-
-            var item = new Video();
-            var imageProvider = GetImageProvider(imageType, imageCount, true);
-
-            var itemImageProvider = GetItemImageProvider(null, null);
-            var changed = itemImageProvider.ValidateImages(item, new[] { imageProvider }, null);
-
-            Assert.True(changed);
-            Assert.Equal(imageCount, item.GetImages(imageType).Count());
+            ValidateImages_Test(imageType, 0, true, imageCount, true, imageCount);
         }
 
         [Theory]
         [MemberData(nameof(GetImageTypesWithCount))]
         public void ValidateImages_PopulatedItemWithGoodPathsAndEmptyProviders_NoChange(ImageType imageType, int imageCount)
         {
-            var item = GetItemWithImages(imageType, imageCount, true);
-
-            var itemImageProvider = GetItemImageProvider(null, null);
-            var changed = itemImageProvider.ValidateImages(item, Enumerable.Empty<ILocalImageProvider>(), null);
-
-            Assert.False(changed);
-            Assert.Equal(imageCount, item.GetImages(imageType).Count());
+            ValidateImages_Test(imageType, imageCount, true, 0, false, imageCount);
         }
 
         [Theory]
         [MemberData(nameof(GetImageTypesWithCount))]
         public void ValidateImages_PopulatedItemWithBadPathsAndEmptyProviders_RemovesImage(ImageType imageType, int imageCount)
         {
-            var item = GetItemWithImages(imageType, imageCount, false);
+            ValidateImages_Test(imageType, imageCount, false, 0, true, 0);
+        }
+
+        private void ValidateImages_Test(ImageType imageType, int initialImageCount, bool initialPathsValid, int providerImageCount, bool expectedChange, int expectedImageCount)
+        {
+            var item = GetItemWithImages(imageType, initialImageCount, initialPathsValid);
+
+            var imageProvider = GetImageProvider(imageType, providerImageCount, true);
 
             var itemImageProvider = GetItemImageProvider(null, null);
-            var changed = itemImageProvider.ValidateImages(item, Enumerable.Empty<ILocalImageProvider>(), null);
+            var actualChange = itemImageProvider.ValidateImages(item, new[] { imageProvider }, null);
 
-            Assert.True(changed);
-            Assert.Empty(item.GetImages(imageType));
+            Assert.Equal(expectedChange, actualChange);
+            Assert.Equal(expectedImageCount, item.GetImages(imageType).Count());
         }
 
         [Fact]
@@ -137,20 +124,23 @@ namespace Jellyfin.Providers.Tests.Manager
         }
 
         [Theory]
-        [MemberData(nameof(GetImageTypesWithCount))]
-        public void MergeImages_PopulatedItemWithGoodPathsAndSameNewImages_NoChange(ImageType imageType, int imageCount)
+        [InlineData(ImageType.Primary, 1, false)]
+        [InlineData(ImageType.Backdrop, 2, false)]
+        [InlineData(ImageType.Primary, 1, true)]
+        [InlineData(ImageType.Backdrop, 2, true)]
+        public void MergeImages_PopulatedItemWithGoodPathsAndSameNewImages_ResetIfTimeChanges(ImageType imageType, int imageCount, bool updateTime)
         {
             var oldTime = new DateTime(1970, 1, 1);
+            var updatedTime = updateTime ? new DateTime(2021, 1, 1) : oldTime;
 
-            // match update time with time added to item images (unix epoch)
             var fileSystem = new Mock<IFileSystem>();
             fileSystem.Setup(fs => fs.GetLastWriteTimeUtc(It.IsAny<FileSystemMetadata>()))
-                .Returns(oldTime);
+                .Returns(updatedTime);
             BaseItem.FileSystem = fileSystem.Object;
 
             // all valid paths - matching for strictly updating
             var item = GetItemWithImages(imageType, imageCount, true);
-            // set size to non-zero to allow for updates to occur
+            // set size to non-zero to allow for image size reset to occur
             foreach (var image in item.GetImages(imageType))
             {
                 image.DateModified = oldTime;
@@ -163,45 +153,52 @@ namespace Jellyfin.Providers.Tests.Manager
             var itemImageProvider = GetItemImageProvider(null, fileSystem);
             var changed = itemImageProvider.MergeImages(item, images);
 
-            Assert.False(changed);
+            if (updateTime)
+            {
+                Assert.True(changed);
+                // before and after paths are the same, verify updated by size reset to 0
+                var typedImages = item.GetImages(imageType).ToArray();
+                Assert.Equal(imageCount, typedImages.Length);
+                foreach (var image in typedImages)
+                {
+                    Assert.Equal(updatedTime, image.DateModified);
+                    Assert.Equal(0, image.Height);
+                    Assert.Equal(0, image.Width);
+                }
+            }
+            else
+            {
+                Assert.False(changed);
+            }
         }
 
         [Theory]
-        [MemberData(nameof(GetImageTypesWithCount))]
-        public void MergeImages_PopulatedItemWithGoodPathsAndSameNewImagesWithNewTimestamps_ResetsImageSizes(ImageType imageType, int imageCount)
+        [InlineData(ImageType.Primary, 0)]
+        [InlineData(ImageType.Primary, 1)]
+        [InlineData(ImageType.Backdrop, 2)]
+        public void RemoveImages_DeletesImages_WhenFound(ImageType imageType, int imageCount)
         {
-            var oldTime = new DateTime(1970, 1, 1);
-            var updatedTime = new DateTime(2021, 1, 1);
-
-            var fileSystem = new Mock<IFileSystem>();
-            fileSystem.Setup(fs => fs.GetLastWriteTimeUtc(It.IsAny<FileSystemMetadata>()))
-                .Returns(updatedTime);
-            BaseItem.FileSystem = fileSystem.Object;
+            var item = GetItemWithImages(imageType, imageCount, false);
 
-            // all valid paths - matching for strictly updating
-            var item = GetItemWithImages(imageType, imageCount, true);
-            // set size to non-zero to allow for image size reset to occur
-            foreach (var image in item.GetImages(imageType))
+            var mockFileSystem = new Mock<IFileSystem>(MockBehavior.Strict);
+            if (imageCount > 0)
             {
-                image.DateModified = oldTime;
-                image.Height = 1;
-                image.Width = 1;
+                mockFileSystem.Setup(fs => fs.DeleteFile("invalid path 0"))
+                    .Verifiable();
             }
 
-            var images = GetImages(imageType, imageCount, true);
-
-            var itemImageProvider = GetItemImageProvider(null, fileSystem);
-            var changed = itemImageProvider.MergeImages(item, images);
-
-            Assert.True(changed);
-            // before and after paths are the same, verify updated by size reset to 0
-            Assert.Equal(imageCount, item.GetImages(imageType).Count());
-            foreach (var image in item.GetImages(imageType))
+            if (imageCount > 1)
             {
-                Assert.Equal(updatedTime, image.DateModified);
-                Assert.Equal(0, image.Height);
-                Assert.Equal(0, image.Width);
+                mockFileSystem.Setup(fs => fs.DeleteFile("invalid path 1"))
+                    .Verifiable();
             }
+
+            var itemImageProvider = GetItemImageProvider(Mock.Of<IProviderManager>(), mockFileSystem);
+            var result = itemImageProvider.RemoveImages(item);
+
+            Assert.Equal(imageCount != 0, result);
+            Assert.Empty(item.GetImages(imageType));
+            mockFileSystem.Verify();
         }
 
         [Theory]
@@ -336,8 +333,7 @@ namespace Jellyfin.Providers.Tests.Manager
                 remoteInfo[i] = new RemoteImageInfo
                 {
                     Type = imageType,
-                    Url = "image url " + i,
-                    Width = 1 // min width is set to 0, this will always pass
+                    Url = "image url " + i
                 };
             }
 
@@ -403,11 +399,10 @@ namespace Jellyfin.Providers.Tests.Manager
             var remoteInfo = new RemoteImageInfo[targetImageCount];
             for (int i = 0; i < targetImageCount; i++)
             {
-                remoteInfo[i] = new RemoteImageInfo()
+                remoteInfo[i] = new RemoteImageInfo
                 {
                     Type = imageType,
-                    Url = "image url " + i,
-                    Width = 1 // min width is set to 0, this will always pass
+                    Url = "image url " + i
                 };
             }
 
@@ -449,11 +444,10 @@ namespace Jellyfin.Providers.Tests.Manager
             var remoteInfo = new RemoteImageInfo[remoteInfoCount];
             for (int i = 0; i < remoteInfoCount; i++)
             {
-                remoteInfo[i] = new RemoteImageInfo()
+                remoteInfo[i] = new RemoteImageInfo
                 {
                     Type = imageType,
-                    Url = "image url " + i,
-                    Width = 1 // min width is set to 0, this will always pass
+                    Url = "image url " + i
                 };
             }
 
@@ -500,6 +494,62 @@ namespace Jellyfin.Providers.Tests.Manager
             Assert.Equal(imageCount, item.GetImages(imageType).Count());
         }
 
+        [Theory]
+        [InlineData(9, false)]
+        [InlineData(10, true)]
+        [InlineData(null, true)]
+        public async void RefreshImages_ProviderRemote_FiltersByWidth(int? remoteImageWidth, bool expectedToUpdate)
+        {
+            var imageType = ImageType.Primary;
+
+            var item = new Video();
+
+            var libraryOptions = new LibraryOptions
+            {
+                TypeOptions = new[]
+                {
+                    new TypeOptions
+                    {
+                        Type = item.GetType().Name,
+                        ImageOptions = new[]
+                        {
+                            new ImageOption
+                            {
+                                Type = imageType,
+                                MinWidth = 10
+                            }
+                        }
+                    }
+                }
+            };
+
+            var remoteProvider = new Mock<IRemoteImageProvider>(MockBehavior.Strict);
+            remoteProvider.Setup(rp => rp.Name).Returns("MockRemoteProvider");
+            remoteProvider.Setup(rp => rp.GetSupportedImages(item))
+                .Returns(new[] { imageType });
+
+            var refreshOptions = new ImageRefreshOptions(Mock.Of<IDirectoryService>());
+
+            // set width on image from remote
+            var remoteInfo = new[]
+            {
+                new RemoteImageInfo()
+                {
+                    Type = imageType,
+                    Url = "image url",
+                    Width = remoteImageWidth
+                }
+            };
+
+            var providerManager = new Mock<IProviderManager>(MockBehavior.Strict);
+            providerManager.Setup(pm => pm.GetAvailableRemoteImages(It.IsAny<BaseItem>(), It.IsAny<RemoteImageQuery>(), It.IsAny<CancellationToken>()))
+                .ReturnsAsync(remoteInfo);
+            var itemImageProvider = GetItemImageProvider(providerManager.Object, null);
+            var result = await itemImageProvider.RefreshImages(item, libraryOptions, new List<IImageProvider> { remoteProvider.Object }, refreshOptions, CancellationToken.None);
+
+            Assert.Equal(expectedToUpdate, result.UpdateType.HasFlag(ItemUpdateType.ImageUpdate));
+        }
+
         private static ItemImageProvider GetItemImageProvider(IProviderManager? providerManager, Mock<IFileSystem>? mockFileSystem)
         {
             // strict to ensure this isn't accidentally used where a prepared mock is intended
@@ -586,7 +636,6 @@ namespace Jellyfin.Providers.Tests.Manager
                             {
                                 Type = type,
                                 Limit = count,
-                                MinWidth = 0
                             }
                         }
                     }
diff --git a/tests/Jellyfin.Providers.Tests/Manager/MetadataServiceTests.cs b/tests/Jellyfin.Providers.Tests/Manager/MetadataServiceTests.cs
new file mode 100644
index 000000000..b74b331b7
--- /dev/null
+++ b/tests/Jellyfin.Providers.Tests/Manager/MetadataServiceTests.cs
@@ -0,0 +1,378 @@
+using System;
+using System.Collections.Generic;
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Controller.Entities.Audio;
+using MediaBrowser.Controller.Entities.Movies;
+using MediaBrowser.Controller.Entities.TV;
+using MediaBrowser.Controller.Providers;
+using MediaBrowser.Model.Entities;
+using MediaBrowser.Providers.Manager;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Manager
+{
+    public class MetadataServiceTests
+    {
+        [Theory]
+        [InlineData(false, false)]
+        [InlineData(true, false)]
+        [InlineData(true, true)]
+        public void MergeBaseItemData_MergeMetadataSettings_MergesWhenSet(bool mergeMetadataSettings, bool defaultDate)
+        {
+            var newLocked = new[] { MetadataField.Cast };
+            var newString = "new";
+            var newDate = DateTime.Now;
+
+            var oldLocked = new[] { MetadataField.Genres };
+            var oldString = "old";
+            var oldDate = DateTime.UnixEpoch;
+
+            var source = new MetadataResult<Movie>
+            {
+                Item = new Movie
+                {
+                    LockedFields = newLocked,
+                    IsLocked = true,
+                    PreferredMetadataCountryCode = newString,
+                    PreferredMetadataLanguage = newString,
+                    DateCreated = newDate
+                }
+            };
+            if (defaultDate)
+            {
+                source.Item.DateCreated = default;
+            }
+
+            var target = new MetadataResult<Movie>
+            {
+                Item = new Movie
+                {
+                    LockedFields = oldLocked,
+                    IsLocked = false,
+                    PreferredMetadataCountryCode = oldString,
+                    PreferredMetadataLanguage = oldString,
+                    DateCreated = oldDate
+                }
+            };
+
+            MetadataService<Movie, MovieInfo>.MergeBaseItemData(source, target, Array.Empty<MetadataField>(), true, mergeMetadataSettings);
+
+            if (mergeMetadataSettings)
+            {
+                Assert.Equal(newLocked, target.Item.LockedFields);
+                Assert.True(target.Item.IsLocked);
+                Assert.Equal(newString, target.Item.PreferredMetadataCountryCode);
+                Assert.Equal(newString, target.Item.PreferredMetadataLanguage);
+                Assert.Equal(defaultDate ? oldDate : newDate, target.Item.DateCreated);
+            }
+            else
+            {
+                Assert.Equal(oldLocked, target.Item.LockedFields);
+                Assert.False(target.Item.IsLocked);
+                Assert.Equal(oldString, target.Item.PreferredMetadataCountryCode);
+                Assert.Equal(oldString, target.Item.PreferredMetadataLanguage);
+                Assert.Equal(oldDate, target.Item.DateCreated);
+            }
+        }
+
+        [Theory]
+        [InlineData("Name", MetadataField.Name, false)]
+        [InlineData("OriginalTitle", null, false)]
+        [InlineData("OfficialRating", MetadataField.OfficialRating)]
+        [InlineData("CustomRating")]
+        [InlineData("Tagline")]
+        [InlineData("Overview", MetadataField.Overview)]
+        [InlineData("DisplayOrder", null, false)]
+        [InlineData("ForcedSortName", null, false)]
+        public void MergeBaseItemData_StringField_ReplacesAppropriately(string propName, MetadataField? lockField = null, bool replacesWithEmpty = true)
+        {
+            var oldValue = "Old";
+            var newValue = "New";
+
+            // Use type Series to hit DisplayOrder
+            Assert.False(TestMergeBaseItemData<Series, SeriesInfo>(propName, oldValue, newValue, null, false, out _));
+            if (lockField != null)
+            {
+                Assert.False(TestMergeBaseItemData<Series, SeriesInfo>(propName, oldValue, newValue, lockField, true, out _));
+                Assert.False(TestMergeBaseItemData<Series, SeriesInfo>(propName, null, newValue, lockField, false, out _));
+                Assert.False(TestMergeBaseItemData<Series, SeriesInfo>(propName, string.Empty, newValue, lockField, false, out _));
+            }
+
+            Assert.True(TestMergeBaseItemData<Series, SeriesInfo>(propName, oldValue, newValue, null, true, out _));
+            Assert.True(TestMergeBaseItemData<Series, SeriesInfo>(propName, null, newValue, null, false, out _));
+            Assert.True(TestMergeBaseItemData<Series, SeriesInfo>(propName, string.Empty, newValue, null, false, out _));
+
+            var replacedWithEmpty = TestMergeBaseItemData<Series, SeriesInfo>(propName, oldValue, string.Empty, null, true, out _);
+            Assert.Equal(replacesWithEmpty, replacedWithEmpty);
+        }
+
+        [Theory]
+        [InlineData("Genres", MetadataField.Genres)]
+        [InlineData("Studios", MetadataField.Studios)]
+        [InlineData("Tags", MetadataField.Tags)]
+        [InlineData("ProductionLocations", MetadataField.ProductionLocations)]
+        [InlineData("AlbumArtists")]
+        public void MergeBaseItemData_StringArrayField_ReplacesAppropriately(string propName, MetadataField? lockField = null)
+        {
+            // Note that arrays are replaced, not merged
+            var oldValue = new[] { "Old" };
+            var newValue = new[] { "New" };
+
+            // Use type Audio to hit AlbumArtists
+            Assert.False(TestMergeBaseItemData<Audio, SongInfo>(propName, oldValue, newValue, null, false, out _));
+            if (lockField != null)
+            {
+                Assert.False(TestMergeBaseItemData<Audio, SongInfo>(propName, oldValue, newValue, lockField, true, out _));
+                Assert.False(TestMergeBaseItemData<Audio, SongInfo>(propName, Array.Empty<string>(), newValue, lockField, false, out _));
+            }
+
+            Assert.True(TestMergeBaseItemData<Audio, SongInfo>(propName, oldValue, newValue, null, true, out _));
+            Assert.True(TestMergeBaseItemData<Audio, SongInfo>(propName, Array.Empty<string>(), newValue, null, false, out _));
+
+            Assert.True(TestMergeBaseItemData<Audio, SongInfo>(propName, oldValue, Array.Empty<string>(), null, true, out _));
+        }
+
+        private static TheoryData<string, object, object> MergeBaseItemData_SimpleField_ReplacesAppropriately_TestData()
+            => new()
+            {
+                { "IndexNumber", 1, 2 },
+                { "ParentIndexNumber", 1, 2 },
+                { "ProductionYear", 1, 2 },
+                { "CommunityRating", 1.0f, 2.0f },
+                { "CriticRating", 1.0f, 2.0f },
+                { "EndDate", DateTime.UnixEpoch, DateTime.Now },
+                { "PremiereDate", DateTime.UnixEpoch, DateTime.Now },
+                { "Video3DFormat", Video3DFormat.HalfSideBySide, Video3DFormat.FullSideBySide }
+            };
+
+        [Theory]
+        [MemberData(nameof(MergeBaseItemData_SimpleField_ReplacesAppropriately_TestData))]
+        public void MergeBaseItemData_SimpleField_ReplacesAppropriately(string propName, object oldValue, object newValue)
+        {
+            // Use type Movie to allow testing of Video3DFormat
+            Assert.False(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, newValue, null, false, out _));
+
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, newValue, null, true, out _));
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, null, newValue, null, false, out _));
+
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, null, null, true, out _));
+        }
+
+        [Fact]
+        public void MergeBaseItemData_MergeTrailers_ReplacesAppropriately()
+        {
+            string propName = "RemoteTrailers";
+            var oldValue = new[]
+            {
+                new MediaUrl
+                {
+                    Name = "Name 1",
+                    Url = "URL 1"
+                }
+            };
+            var newValue = new[]
+            {
+                new MediaUrl
+                {
+                    Name = "Name 2",
+                    Url = "URL 2"
+                }
+            };
+
+            Assert.False(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, newValue, null, false, out _));
+
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, newValue, null, true, out _));
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, Array.Empty<MediaUrl>(), newValue, null, false, out _));
+
+            Assert.True(TestMergeBaseItemData<Movie, MovieInfo>(propName, oldValue, Array.Empty<MediaUrl>(), null, true, out _));
+        }
+
+        [Fact]
+        public void MergeBaseItemData_ProviderIds_MergesAppropriately()
+        {
+            var propName = "ProviderIds";
+            var oldValue = new Dictionary<string, string>
+            {
+                { "provider 1", "id 1" }
+            };
+
+            // overwrite provider id
+            var overwriteNewValue = new Dictionary<string, string>
+            {
+                { "provider 1", "id 2" }
+            };
+            Assert.False(TestMergeBaseItemData<Movie, MovieInfo>(propName, new Dictionary<string, string>(oldValue), overwriteNewValue, null, false, out _));
+            TestMergeBaseItemData<Movie, MovieInfo>(propName, new Dictionary<string, string>(oldValue), overwriteNewValue, null, true, out var overwritten);
+            Assert.Equal(overwriteNewValue, overwritten);
+
+            // merge without overwriting
+            var mergeNewValue = new Dictionary<string, string>
+            {
+                { "provider 1", "id 2" },
+                { "provider 2", "id 3" }
+            };
+            TestMergeBaseItemData<Movie, MovieInfo>(propName, new Dictionary<string, string>(oldValue), mergeNewValue, null, false, out var merged);
+            var actual = (Dictionary<string, string>)merged!;
+            Assert.Equal("id 1", actual["provider 1"]);
+            Assert.Equal("id 3", actual["provider 2"]);
+
+            // empty source results in no change
+            TestMergeBaseItemData<Movie, MovieInfo>(propName, new Dictionary<string, string>(oldValue), new Dictionary<string, string>(), null, true, out var notOverwritten);
+            Assert.Equal(oldValue, notOverwritten);
+        }
+
+        [Fact]
+        public void MergeBaseItemData_MergePeople_MergesAppropriately()
+        {
+            // PersonInfo in list is changed by merge, create new for every call
+            List<PersonInfo> GetOldValue()
+                => new()
+                {
+                    new PersonInfo
+                    {
+                        Name = "Name 1",
+                        ProviderIds = new Dictionary<string, string>
+                        {
+                            { "Provider 1", "1234" }
+                        }
+                    }
+                };
+
+            object? result;
+            List<PersonInfo> actual;
+
+            // overwrite provider id
+            var overwriteNewValue = new List<PersonInfo>
+            {
+                new()
+                {
+                    Name = "Name 2"
+                }
+            };
+            Assert.False(TestMergeBaseItemDataPerson(GetOldValue(), overwriteNewValue, null, false, out result));
+            // People not already in target are not merged into it from source
+            actual = (List<PersonInfo>)result!;
+            Assert.Single(actual);
+            Assert.Equal("Name 1", actual[0].Name);
+
+            Assert.True(TestMergeBaseItemDataPerson(GetOldValue(), overwriteNewValue, null, true, out _));
+            Assert.True(TestMergeBaseItemDataPerson(new List<PersonInfo>(), overwriteNewValue, null, false, out _));
+            Assert.True(TestMergeBaseItemDataPerson(null, overwriteNewValue, null, false, out _));
+
+            Assert.False(TestMergeBaseItemDataPerson(GetOldValue(), overwriteNewValue, MetadataField.Cast, true, out _));
+
+            // providers merge but don't overwrite existing keys
+            var mergeNewValue = new List<PersonInfo>
+            {
+                new()
+                {
+                    Name = "Name 1",
+                    ProviderIds = new Dictionary<string, string>
+                    {
+                        { "Provider 1", "5678" },
+                        { "Provider 2", "5678" }
+                    }
+                }
+            };
+            TestMergeBaseItemDataPerson(GetOldValue(), mergeNewValue, null, false, out result);
+            actual = (List<PersonInfo>)result!;
+            Assert.Single(actual);
+            Assert.Equal("Name 1", actual[0].Name);
+            Assert.Equal(2, actual[0].ProviderIds.Count);
+            Assert.Equal("1234", actual[0].ProviderIds["Provider 1"]);
+            Assert.Equal("5678", actual[0].ProviderIds["Provider 2"]);
+
+            // picture adds if missing but won't overwrite (forcing overwrites entire list, not entries in merged PersonInfo)
+            var mergePicture1 = new List<PersonInfo>
+            {
+                new()
+                {
+                    Name = "Name 1",
+                    ImageUrl = "URL 1"
+                }
+            };
+            TestMergeBaseItemDataPerson(GetOldValue(), mergePicture1, null, false, out result);
+            actual = (List<PersonInfo>)result!;
+            Assert.Single(actual);
+            Assert.Equal("Name 1", actual[0].Name);
+            Assert.Equal("URL 1", actual[0].ImageUrl);
+            var mergePicture2 = new List<PersonInfo>
+            {
+                new()
+                {
+                    Name = "Name 1",
+                    ImageUrl = "URL 2"
+                }
+            };
+            TestMergeBaseItemDataPerson(mergePicture1, mergePicture2, null, false, out result);
+            actual = (List<PersonInfo>)result!;
+            Assert.Single(actual);
+            Assert.Equal("Name 1", actual[0].Name);
+            Assert.Equal("URL 1", actual[0].ImageUrl);
+
+            // empty source can be forced to overwrite a target with data
+            Assert.True(TestMergeBaseItemDataPerson(GetOldValue(), new List<PersonInfo>(), null, true, out _));
+        }
+
+        private static bool TestMergeBaseItemDataPerson(List<PersonInfo>? oldValue, List<PersonInfo>? newValue, MetadataField? lockField, bool replaceData, out object? actualValue)
+        {
+            var source = new MetadataResult<Movie>
+            {
+                Item = new Movie(),
+                People = newValue
+            };
+
+            var target = new MetadataResult<Movie>
+            {
+                Item = new Movie(),
+                People = oldValue
+            };
+
+            var lockedFields = lockField == null ? Array.Empty<MetadataField>() : new[] { (MetadataField)lockField };
+            MetadataService<Movie, MovieInfo>.MergeBaseItemData(source, target, lockedFields, replaceData, false);
+
+            actualValue = target.People;
+            return newValue?.Equals(actualValue) ?? actualValue == null;
+        }
+
+        /// <summary>
+        /// Makes a call to <see cref="MetadataService{TItemType,TIdType}.MergeBaseItemData"/> with the provided parameters and returns whether the target changed or not.
+        ///
+        /// Reflection is used to allow testing of all fields using the same logic, rather than relying on copy/pasting test code for each field.
+        /// </summary>
+        /// <param name="propName">The property to test.</param>
+        /// <param name="oldValue">The initial value in the target object.</param>
+        /// <param name="newValue">The initial value in the source object.</param>
+        /// <param name="lockField">The metadata field that locks this property if the field should be locked, or <c>null</c> to leave unlocked.</param>
+        /// <param name="replaceData">Passed through to <see cref="MetadataService{TItemType,TIdType}.MergeBaseItemData"/>.</param>
+        /// <param name="actualValue">The resulting value set to the target.</param>
+        /// <typeparam name="TItemType">The <see cref="BaseItem"/> type to test on.</typeparam>
+        /// <typeparam name="TIdType">The <see cref="BaseItem"/> info type.</typeparam>
+        /// <returns><c>true</c> if the property on the target updates to match the source value when<see cref="MetadataService{TItemType,TIdType}.MergeBaseItemData"/> is called.</returns>
+        private static bool TestMergeBaseItemData<TItemType, TIdType>(string propName, object? oldValue, object? newValue, MetadataField? lockField, bool replaceData, out object? actualValue)
+            where TItemType : BaseItem, IHasLookupInfo<TIdType>, new()
+            where TIdType : ItemLookupInfo, new()
+        {
+            var property = typeof(TItemType).GetProperty(propName)!;
+
+            var source = new MetadataResult<TItemType>
+            {
+                Item = new TItemType()
+            };
+            property.SetValue(source.Item, newValue);
+
+            var target = new MetadataResult<TItemType>
+            {
+                Item = new TItemType()
+            };
+            property.SetValue(target.Item, oldValue);
+
+            var lockedFields = lockField == null ? Array.Empty<MetadataField>() : new[] { (MetadataField)lockField };
+            // generic type doesn't actually matter to call the static method, just has to be filled in
+            MetadataService<TItemType, TIdType>.MergeBaseItemData(source, target, lockedFields, replaceData, false);
+
+            actualValue = property.GetValue(target.Item);
+            return newValue?.Equals(actualValue) ?? actualValue == null;
+        }
+    }
+}