[Xamarin.Android.Build.Tasks] Deploy changes to transitive reference assembly dependencies

Documentation/release-notes/transitive-refasm.md

@@ -0,0 +1,8 @@
+#### Application and library build and deployment
+
+- [Developer Community 1086457](https://developercommunity.visualstudio.com/content/problem/1086457/index.html):
+  Changes to libraries referenced by the .NET Standard library in a default
+  Xamarin.Forms project were not reflected in the running app without a clean
+  rebuild.  More generally, this issue affected any library referenced
+  indirectly via a .NET Standard library that had the
+  `ProduceReferenceAssembly` MSBuild property set to `true`.

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/BuildTest.cs

@@ -2692,7 +2692,7 @@ public void BuildWithResolveAssembliesFailure ([Values (true, false)] bool usePa
 					Assert.IsTrue (appBuilder.LastBuildOutput.ContainsText ($"{error} `Microsoft.Azure.EventHubs`, referenced by `MyLibrary`. Please add a NuGet package or assembly reference for `Microsoft.Azure.EventHubs`, or remove the reference to `MyLibrary`."),
 						$"Should recieve '{error}' regarding `Microsoft.Azure.EventHubs`!");
 				} else {
-					Assert.IsTrue (appBuilder.LastBuildOutput.ContainsText ($"{error} `Microsoft.Azure.Amqp`, referenced by `MyLibrary` > `Microsoft.Azure.EventHubs`. Please add a NuGet package or assembly reference for `Microsoft.Azure.Amqp`, or remove the reference to `MyLibrary`."),
+					Assert.IsTrue (appBuilder.LastBuildOutput.ContainsText ($"{error} `Microsoft.Azure.Amqp`, referenced by `Microsoft.Azure.EventHubs`. Please add a NuGet package or assembly reference for `Microsoft.Azure.Amqp`, or remove the reference to `Microsoft.Azure.EventHubs`"),
 						$"Should recieve '{error}' regarding `Microsoft.Azure.Amqp`!");
 				}
 				//Now add the PackageReference to the app to see a different error message

src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/IncrementalBuildTest.cs

@@ -516,6 +516,68 @@ public void ProduceReferenceAssembly ()
 			}
 		}
 
+		[Test]
+		public void TransitiveDependencyProduceReferenceAssembly ()
+		{
+			var path = Path.Combine (Root, "temp", TestName);
+			var app = new XamarinAndroidApplicationProject {
+				ProjectName = "App",
+				Sources = {
+					new BuildItem.Source ("Class1.cs") {
+						TextContent = () => "public class Class1 : Library1.Class1 { }"
+					},
+				}
+			};
+			var lib1 = new DotNetStandard {
+				ProjectName = "Library1",
+				Sdk = "Microsoft.NET.Sdk",
+				TargetFramework = "netstandard2.0",
+				Sources = {
+					new BuildItem.Source ("Class1.cs") {
+						TextContent = () => "namespace Library1 { public class Class1 { } }"
+					},
+					new BuildItem.Source ("Class2.cs") {
+						TextContent = () => "namespace Library1 { public class Class2 : Library2.Class1 { } }"
+					}
+				}
+			};
+			lib1.SetProperty ("ProduceReferenceAssembly", "True");
+			var lib2 = new DotNetStandard {
+				ProjectName = "Library2",
+				Sdk = "Microsoft.NET.Sdk",
+				TargetFramework = "netstandard2.0",
+				Sources = {
+					new BuildItem.Source ("Class1.cs") {
+						TextContent = () => "namespace Library2 { public class Class1 { } }"
+					},
+				}
+			};
+			lib2.SetProperty ("ProduceReferenceAssembly", "True");
+			lib1.OtherBuildItems.Add (new BuildItem.ProjectReference ($"..\\{lib2.ProjectName}\\{lib2.ProjectName}.csproj", lib2.ProjectName, lib2.ProjectGuid));
+			app.References.Add (new BuildItem.ProjectReference ($"..\\{lib1.ProjectName}\\{lib1.ProjectName}.csproj", lib1.ProjectName, lib1.ProjectGuid));
+
+			using (var lib2Builder = CreateDllBuilder (Path.Combine (path, lib2.ProjectName), cleanupAfterSuccessfulBuild: false))
+			using (var lib1Builder = CreateDllBuilder (Path.Combine (path, lib1.ProjectName), cleanupAfterSuccessfulBuild: false))
+			using (var appBuilder = CreateApkBuilder (Path.Combine (path, app.ProjectName))) {
+				Assert.IsTrue (lib2Builder.Build (lib2), "first Library2 build should have succeeded.");
+				Assert.IsTrue (lib1Builder.Build (lib1), "first Library1 build should have succeeded.");
+				Assert.IsTrue (appBuilder.Build (app), "first app build should have succeeded.");
+
+				lib2.Sources.Add (new BuildItem.Source ("Class2.cs") {
+					TextContent = () => "namespace Library2 { public class Class2 { } }"
+				});
+
+				Assert.IsTrue (lib2Builder.Build (lib2, doNotCleanupOnUpdate: true), "second Library2 build should have succeeded.");
+				Assert.IsTrue (lib1Builder.Build (lib1, doNotCleanupOnUpdate: true, saveProject: false), "second Library1 build should have succeeded.");
+				appBuilder.Target = "SignAndroidPackage";
+				Assert.IsTrue (appBuilder.Build (app, doNotCleanupOnUpdate: true, saveProject: false), "app SignAndroidPackage build should have succeeded.");
+
+				var lib2Output = Path.Combine (path, lib2.ProjectName, "bin", "Debug", "netstandard2.0", $"{lib2.ProjectName}.dll");
+				var lib2InAppOutput = Path.Combine (path, app.ProjectName, app.IntermediateOutputPath, "android", "assets", $"{lib2.ProjectName}.dll");
+				FileAssert.AreEqual (lib2Output, lib2InAppOutput, "new Library2 should have been copied to app output directory");
+			}
+		}
+
 		[Test]
 		[Category ("dotnet")]
 		public void LinkAssembliesNoShrink ()

src/Xamarin.Android.Build.Tasks/Xamarin.Android.Legacy.targets

@@ -258,14 +258,18 @@ projects. .NET 5 projects will not import this file.
           Include="@(ReferenceCopyLocalPaths)"
           Condition="'%(ReferenceCopyLocalPaths.ResolvedFrom)' != 'ImplicitlyExpandDesignTimeFacades' And '%(ReferenceCopyLocalPaths.Extension)' == '.dll' And '%(ReferenceCopyLocalPaths.RelativeDir)' == '' And Exists('%(ReferenceCopyLocalPaths.Identity)') "
       />
+      <FilteredAssemblies
+          Include="@(_ReferenceDependencyPaths)"
+          Condition="'%(_ReferenceDependencyPaths.ResolvedFrom)' != 'ImplicitlyExpandDesignTimeFacades' And Exists('%(_ReferenceDependencyPaths.Identity)') "
+      />
       <FilteredAssemblies
           Include="@(_ReferencePath)"
           Condition="'%(ReferencePath.ResolvedFrom)' != 'ImplicitlyExpandDesignTimeFacades' And Exists('%(_ReferencePath.Identity)') "
       />
     </ItemGroup>
     <!-- Find all the assemblies this app requires -->
     <ResolveAssemblies
-        Assemblies="@(FilteredAssemblies)"
+        Assemblies="@(FilteredAssemblies->Distinct())"
         I18nAssemblies="$(MandroidI18n)"
         LinkMode="$(AndroidLinkMode)"
         ProjectFile="$(MSBuildProjectFullPath)"