[tests] Add a test to verify and keep track of app size changes.

tests/dotnet/SizeTestApp/AppDelegate.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Runtime.InteropServices;
+
+using Foundation;
+#if HAS_UIKIT
+using UIKit;
+#endif
+
+namespace MySimpleApp {
+	public class Program {
+		static int Main (string [] args)
+		{
+#if HAS_UIKIT
+
+			UIApplication.Main (args, null, typeof (AppDelegate));
+#else
+			NSApplication.Init ();
+			NSApplication.Main (args);
+#endif
+			return 0;
+		}
+	}
+
+#if HAS_UIKIT
+	public partial class AppDelegate : UIApplicationDelegate {
+		UIWindow window;
+
+		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
+		{
+			window = new UIWindow (UIScreen.MainScreen.Bounds);
+
+			var dvc = new UIViewController ();
+			var button = new UIButton (window.Bounds);
+			button.SetTitle ("Hello .NET!", UIControlState.Normal);
+			dvc.Add (button);
+
+			window.RootViewController = dvc;
+			window.MakeKeyAndVisible ();
+
+			return true;
+		}
+	}
+#else
+#error This test app has not been implemented for AppKit yet.
+#endif
+}

tests/dotnet/SizeTestApp/MacCatalyst/Makefile

@@ -0,0 +1 @@
+include ../shared.mk

tests/dotnet/SizeTestApp/MacCatalyst/MySimpleApp.csproj

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)-maccatalyst</TargetFramework>
+	</PropertyGroup>
+	<Import Project="..\shared.csproj" />
+</Project>

tests/dotnet/SizeTestApp/Makefile

@@ -0,0 +1,2 @@
+TOP=../../..
+include $(TOP)/tests/common/shared-dotnet-test.mk

tests/dotnet/SizeTestApp/iOS/Makefile

@@ -0,0 +1 @@
+include ../shared.mk

tests/dotnet/SizeTestApp/iOS/SizeTestApp.csproj

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)-ios</TargetFramework>
+	</PropertyGroup>
+	<Import Project="..\shared.csproj" />
+</Project>

tests/dotnet/SizeTestApp/macOS/Makefile

@@ -0,0 +1 @@
+include ../shared.mk

tests/dotnet/SizeTestApp/macOS/SizeTestApp.csproj

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)-macos</TargetFramework>
+	</PropertyGroup>
+	<Import Project="..\shared.csproj" />
+</Project>

tests/dotnet/SizeTestApp/shared.csproj

@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project>
+	<PropertyGroup>
+		<OutputType>Exe</OutputType>
+
+		<ApplicationTitle>SizeTestApp</ApplicationTitle>
+		<ApplicationId>com.xamarin.sizetestapp</ApplicationId>
+
+		<ExcludeTouchUnitReference>true</ExcludeTouchUnitReference>
+		<ExcludeNUnitLiteReference>true</ExcludeNUnitLiteReference>
+	</PropertyGroup>
+
+	<Import Project="../../common/shared-dotnet.csproj" />
+
+	<ItemGroup>
+		<Compile Include="../*.cs" />
+	</ItemGroup>
+</Project>

tests/dotnet/SizeTestApp/shared.mk

@@ -0,0 +1,3 @@
+TOP=../../../..
+TESTNAME=SizeTestApp
+include $(TOP)/tests/common/shared-dotnet.mk

tests/dotnet/SizeTestApp/tvOS/Makefile

@@ -0,0 +1 @@
+include ../shared.mk

tests/dotnet/SizeTestApp/tvOS/SizeTestApp.csproj

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net$(BundledNETCoreAppTargetFrameworkVersion)-tvos</TargetFramework>
+	</PropertyGroup>
+	<Import Project="..\shared.csproj" />
+</Project>

tests/dotnet/UnitTests/AppSizeTest.cs

@@ -0,0 +1,127 @@
+// Copyright (c) Microsoft Corporation.
+// Licensed under the MIT License.
+
+using Cecil.Tests;
+using Mono.Cecil;
+
+#nullable enable
+
+namespace Xamarin.Tests {
+	[TestFixture]
+	public class AppSizeTest : TestBaseClass {
+
+		[TestCase (ApplePlatform.iOS, "ios-arm64")]
+		public void MonoVM (ApplePlatform platform, string runtimeIdentifiers)
+		{
+			Run (platform, runtimeIdentifiers, "Release", $"{platform}-MonoVM", true);
+		}
+
+		[TestCase (ApplePlatform.iOS, "ios-arm64")]
+		public void MonoVM_Interpreter (ApplePlatform platform, string runtimeIdentifiers)
+		{
+			Run (platform, runtimeIdentifiers, "Release", $"{platform}-MonoVM-interpreter", true, new Dictionary<string, string> () { { "UseInterpreter", "true" } });
+		}
+
+		[TestCase (ApplePlatform.iOS, "ios-arm64")]
+		public void NativeAOT (ApplePlatform platform, string runtimeIdentifiers)
+		{
+			Run (platform, runtimeIdentifiers, "Release", $"{platform}-NativeAOT", false, new Dictionary<string, string> () { { "PublishAot", "true" } });
+		}
+
+		// This test will build the SizeTestApp, and capture the resulting app size.
+		// The app size is stored in a file on disk, so we can make sure app size doesn't change (or at least we notice it and we can update the known state).
+		// There's a tolerance in the test for minor app size variances, so if this test fails, the current change might not mean there's a big change,
+		// there might just be many cumulative unnoticed/minor app size differences eventually triggering the test.
+		// The test fails even if app size goes down; this way we can also keep track of good news! And additionally we won't miss it if the app size first goes down, then back up again.
+		void Run (ApplePlatform platform, string runtimeIdentifiers, string configuration, string name, bool supportsAssemblyInspection, Dictionary<string, string>? extraProperties = null)
+		{
+			Configuration.IgnoreIfIgnoredPlatform (platform);
+			Configuration.AssertRuntimeIdentifiersAvailable (platform, runtimeIdentifiers);
+
+			var project = "SizeTestApp";
+			var project_path = GetProjectPath (project, runtimeIdentifiers: runtimeIdentifiers, platform: platform, out var appPath, configuration: configuration);
+
+			Clean (project_path);
+
+			var properties = GetDefaultProperties (runtimeIdentifiers, extraProperties: extraProperties);
+			properties ["Configuration"] = configuration;
+
+			DotNet.AssertBuild (project_path, properties);
+
+			// FORCE_UPDATE_KNOWN_FAILURES will update the known failures files even if the test doesn't actually fail
+			// WRITE_KNOWN_FAILURES will only update the known failures files if the test fails
+
+			var forceUpdate = !string.IsNullOrEmpty (Environment.GetEnvironmentVariable ("FORCE_UPDATE_KNOWN_FAILURES"));
+			var update = forceUpdate || !string.IsNullOrEmpty (Environment.GetEnvironmentVariable ("WRITE_KNOWN_FAILURES"));
+			var expectedDirectory = Path.Combine (Configuration.SourceRoot, "tests", "dotnet", "UnitTests", "expected");
+
+			// Compute the size of the app bundle, and compare it to the stored version on disk.
+			var allFiles = Directory.GetFiles (appPath, "*", SearchOption.AllDirectories).Select (v => new FileInfo (v));
+			var appBundleSize = allFiles.Sum (v => v.Length);
+			var report = new StringBuilder ();
+			report.AppendLine ($"AppBundleSize: {FormatBytes (appBundleSize)}");
+			report.AppendLine ($"# The following list of files and their sizes is just informational / for review, and isn't used in the test:");
+			foreach (var file in allFiles.OrderBy (v => v.FullName))
+				report.AppendLine ($"{file.FullName [(appPath.Length + 1)..]}: {FormatBytes (file.Length)}");
+			var expectedSizeReportPath = Path.Combine (expectedDirectory, $"{name}-size.txt");
+			var expectedSizeReport = "";
+			var expectedAppBundleSize = 0L;
+			if (File.Exists (expectedSizeReportPath)) {
+				expectedSizeReport = File.ReadAllText (expectedSizeReportPath);
+				expectedAppBundleSize = long.Parse (expectedSizeReport.SplitLines ().First ().Replace ("AppBundleSize: ", "").RemoveAfterFirstSpace ());
+			}
+
+			var appSizeDifference = appBundleSize - expectedAppBundleSize;
+			if (appSizeDifference == 0 && !forceUpdate)
+				return;
+
+			var toleranceInBytes = 1024 * 10; // 10kb
+			if (toleranceInBytes >= Math.Abs (appSizeDifference)) {
+				Console.WriteLine ($"App size difference is {FormatBytes (appSizeDifference)}, which is less than the tolerance ({toleranceInBytes}), so nothing will be reported.");
+				if (!forceUpdate)
+					return;
+			}
+
+			if (update) {
+				Directory.CreateDirectory (expectedDirectory);
+				File.WriteAllText (expectedSizeReportPath, report.ToString ());
+
+				// Create a file with all the APIs that survived the trimmer; this can be useful to determine what is not trimmed away.
+				// Note that any changes in this list when the test fails might be due to unrelated earlier changes, that didn't trigger the test
+				// to fail, because the corresponding app size difference was within the tolerance for app size changes.
+				if (supportsAssemblyInspection) {
+					var asmDir = Path.Combine (appPath, GetRelativeAssemblyDirectory (platform));
+					var preservedAPIs = new List<string> ();
+					foreach (var dll in Directory.GetFiles (asmDir, "*.dll", SearchOption.AllDirectories)) {
+						var relativePath = dll [(asmDir.Length + 1)..];
+						using var ad = AssemblyDefinition.ReadAssembly (dll, new ReaderParameters { ReadingMode = ReadingMode.Deferred });
+						foreach (var member in ad.EnumerateMembers ()) {
+							preservedAPIs.Add ($"{relativePath}:{((ICustomAttributeProvider) member).AsFullName ()}");
+						}
+					}
+					preservedAPIs.Sort ();
+					var expectedFile = Path.Combine (expectedDirectory, $"{name}-preservedapis.txt");
+					File.WriteAllLines (expectedFile, preservedAPIs);
+					Console.WriteLine ($"Updated expected results: {expectedFile}");
+				}
+			} else {
+				Assert.Fail ($"App size changed significantly ({FormatBytes (appSizeDifference, true)} different > tolerance of +-{FormatBytes (toleranceInBytes)}). Expected app size: {FormatBytes (expectedAppBundleSize)}, actual app size: {FormatBytes (appBundleSize)}. Set the environment variable WRITE_KNOWN_FAILURES=1, run the test again, and verify the modified files for more information");
+			}
+		}
+
+		static string FormatBytes (long bytes, bool alwaysShowSign = false)
+		{
+			return $"{(alwaysShowSign && bytes > 0 ? "+" : "")}{bytes} bytes ({bytes / 1024.0:0.0} KB = {bytes / (1024.0 * 1024.0):0.0} MB)";
+		}
+	}
+
+	static class StringExtensions {
+		public static string RemoveAfterFirstSpace (this string value)
+		{
+			var sp = value.IndexOf (' ');
+			if (sp == -1)
+				return value;
+			return value [..sp];
+		}
+	}
+}

tests/dotnet/UnitTests/DotNetUnitTests.csproj

@@ -41,6 +41,9 @@
 		<Compile Include="..\..\..\tools\common\Execution.cs">
 			<Link>external\Execution.cs</Link>
 		</Compile>
+		<Compile Include="..\..\..\tools\common\OSPlatformAttributeExtensions.cs">
+			<Link>external\OSPlatformAttributeExtensions.cs</Link>
+		</Compile>
 		<Compile Include="..\..\mtouch\Cache.cs">
 			<Link>external\Cache.cs</Link>
 		</Compile>
@@ -71,6 +74,12 @@
 		<Compile Include="..\..\..\tools\common\error.cs">
 			<Link>external\error.cs</Link>
 		</Compile>
+		<Compile Include="..\..\cecil-tests\CecilExtensions.cs">
+			<Link>external\CecilExtensions.cs</Link>
+		</Compile>
+		<Compile Include="..\..\cecil-tests\Helper.cs">
+			<Link>external\Helper.cs</Link>
+		</Compile>
 	</ItemGroup>
 	<ItemGroup>
 		<Folder Include="external\" />