Merge pull request #4496 from livarcocc/issue_4486

Merging metadata with different values

src/Microsoft.DotNet.ProjectJsonMigration/Transforms/ItemTransformApplicator.cs

@@ -273,8 +273,7 @@ namespace Microsoft.DotNet.ProjectJsonMigration.Transforms
             mergedItem.UnionExcludes(existingItem.Excludes());
             mergedItem.UnionExcludes(item.Excludes());
 
-            mergedItem.AddMetadata(existingItem.Metadata);
+            mergedItem.AddMetadata(MergeMetadata(existingItem.Metadata, item.Metadata));
-            mergedItem.AddMetadata(item.Metadata);
 
             item.RemoveIncludes(commonIncludes);
             existingItem.RemoveIncludes(commonIncludes);
@@ -289,6 +288,37 @@ namespace Microsoft.DotNet.ProjectJsonMigration.Transforms
             return mergeResult;
         }
 
+        private ICollection<ProjectMetadataElement> MergeMetadata(
+            ICollection<ProjectMetadataElement> existingMetadataElements,
+            ICollection<ProjectMetadataElement> newMetadataElements)
+        {
+            var mergedMetadata = new List<ProjectMetadataElement>(existingMetadataElements);
+
+            foreach (var newMetadata in newMetadataElements)
+            {
+                var existingMetadata = mergedMetadata.FirstOrDefault(m =>
+                    m.Name.Equals(newMetadata.Name, StringComparison.OrdinalIgnoreCase));
+                if (existingMetadata == null)
+                {
+                    mergedMetadata.Add(newMetadata);
+                }
+                else
+                {
+                    MergeMetadata(existingMetadata, newMetadata);
+                }
+            }
+
+            return mergedMetadata;
+        }
+
+        public void MergeMetadata(ProjectMetadataElement existingMetadata, ProjectMetadataElement newMetadata)
+        {
+            if (existingMetadata.Value != newMetadata.Value)
+            {
+                existingMetadata.Value = string.Join(";", new [] { existingMetadata.Value, newMetadata.Value });
+            }
+        }
+
         private IEnumerable<ProjectItemElement> FindExistingItemsWithSameCondition(
             ProjectItemElement item, 
             ProjectRootElement project,

test/Microsoft.DotNet.ProjectJsonMigration.Tests/Rules/GivenThatIWantToMigratePackOptions.cs

@@ -260,6 +260,40 @@ namespace Microsoft.DotNet.ProjectJsonMigration.Tests
             contentItems.First().GetMetadataWithName("PackagePath").Value.Should().BeEmpty();
         }
 
+        [Fact]
+        public void Migrating_same_file_with_multiple_mappings_string_joins_the_mappings_in_PackagePath()
+        {
+            var mockProj = RunPackOptionsRuleOnPj(@"
+                {
+                    ""packOptions"": {
+                        ""files"": {
+                            ""include"": [""path/to/some/file.cs""],
+                            ""mappings"": {
+                                ""other/path/file.cs"": ""path/to/some/file.cs"",
+                                ""different/path/file1.cs"": ""path/to/some/file.cs""
+                            }
+                        }
+                    }
+                }");
+
+            var expectedPackagePath = string.Join(
+                ";", 
+                new [] {                    
+                    Path.Combine("different", "path"),
+                    Path.Combine("other", "path")
+                });
+
+            var contentItems = mockProj.Items
+                .Where(item => item.ItemType.Equals("Content", StringComparison.Ordinal))
+                .Where(item =>
+                    item.GetMetadataWithName("Pack").Value == "true" &&
+                    item.GetMetadataWithName("PackagePath") != null);
+
+            contentItems.Count().Should().Be(1);
+            contentItems.First().Include.Should().Be(@"path\to\some\file.cs");
+            contentItems.First().GetMetadataWithName("PackagePath").Value.Should().Be(expectedPackagePath);
+        }
+
         private ProjectRootElement RunPackOptionsRuleOnPj(string packOptions, string testDirectory = null)
         {
             testDirectory = testDirectory ?? Temp.CreateDirectory().Path;