[dotnet] Improve tests to verify that the linker has (or hasn't) run.

tests/common/DotNet.cs

@@ -24,12 +24,19 @@ namespace Xamarin.Tests {
 			}
 		}
 
-		public static void AssertBuild (string project, Dictionary<string, string> properties = null, string verbosity = "diagnostic")
+		public static ExecutionResult AssertBuild (string project, Dictionary<string, string> properties = null, string verbosity = "diagnostic")
 		{
-			Execute ("build", project, properties, out var _, verbosity, true);
+			return Execute ("build", project, properties, verbosity, true);
 		}
 
-		public static int Execute (string verb, string project, Dictionary<string, string> properties, out StringBuilder output, string verbosity = "diagnostic", bool assert_success = true)
+		public static ExecutionResult AssertBuildFailure (string project, Dictionary<string, string> properties = null, string verbosity = "diagnostic")
+		{
+			var rv = Execute ("build", project, properties, verbosity, false);
+			Assert.AreNotEqual (0, rv.ExitCode, "Unexpected success");
+			return rv;
+		}
+
+		public static ExecutionResult Execute (string verb, string project, Dictionary<string, string> properties, string verbosity = "diagnostic", bool assert_success = true)
 		{
 			if (!File.Exists (project))
 				throw new FileNotFoundException ($"The project file '{project}' does not exist.");
@@ -51,7 +58,7 @@ namespace Xamarin.Tests {
 				var env = new Dictionary<string, string> ();
 				env ["MSBuildSDKsPath"] = null;
 				env ["MSBUILD_EXE_PATH"] = null;
-				output = new StringBuilder ();
+				var output = new StringBuilder ();
 				var rv = ExecutionHelper.Execute (Executable, args, env, output, output, workingDirectory: Path.GetDirectoryName (project), timeout: TimeSpan.FromMinutes (10));
 				if (rv != 0) {
 					Console.WriteLine ($"'{Executable} {StringUtils.FormatArguments (args)}' failed with exit code {rv}.");
@@ -65,10 +72,21 @@ namespace Xamarin.Tests {
 						msg = "\n\t" + string.Join ("\n\t", errors);
 					Assert.AreEqual (0, rv, $"Exit code: {Executable} {StringUtils.FormatArguments (args)}{msg}");
 				}
-				return rv;
+				return new ExecutionResult {
+					StandardOutput = output,
+					StandardError = output,
+					ExitCode = rv,
+				};
 			default:
 				throw new NotImplementedException ($"Unknown dotnet action: '{verb}'");
 			}
 		}
 	}
+
+	public class ExecutionResult {
+		public StringBuilder StandardOutput;
+		public StringBuilder StandardError;
+		public int ExitCode;
+		public bool TimedOut;
+	}
 }

tests/dotnet/UnitTests/ProjectTest.cs

@@ -5,7 +5,7 @@ using NUnit.Framework;
 namespace Xamarin.Tests {
 	[TestFixture]
 	public class DotNetProjectTest {
-		void Build (string project, string subdir = null)
+		string GetProjectPath (string project, string subdir = null)
 		{
 			var project_dir = Path.Combine (Configuration.SourceRoot, "tests", "dotnet", project);
 			if (!string.IsNullOrEmpty (subdir))
@@ -15,31 +15,57 @@ namespace Xamarin.Tests {
 			if (!File.Exists (project_path))
 				project_path = Path.ChangeExtension (project_path, "sln");
 
-			DotNet.AssertBuild (project_path);
+			if (!File.Exists (project_path))
+				throw new FileNotFoundException ($"Could not find the project or solution {project}");
+
+			return project_path;
+		}
+
+		void Clean (string project_path)
+		{
+			var dirs = Directory.GetDirectories (Path.GetDirectoryName (project_path), "*", SearchOption.AllDirectories);
+			foreach (var dir in dirs) {
+				var name = Path.GetFileName (dir);
+				if (name != "bin" && name != "obj")
+					continue;
+				Directory.Delete (dir, true);
+			}
 		}
 
 		[Test]
 		public void BuildMySingleView ()
 		{
-			Build ("MySingleView");
+			var project_path = GetProjectPath ("MySingleView");
+			Clean (project_path);
+			var result = DotNet.AssertBuild (project_path);
+			AssertThatLinkerExecuted (result);
 		}
 
 		[Test]
 		public void BuildMyCocoaApp ()
 		{
-			Build ("MyCocoaApp");
+			var project_path = GetProjectPath ("MyCocoaApp");
+			Clean (project_path);
+			var result = DotNet.AssertBuild (project_path);
+			AssertThatLinkerExecuted (result);
 		}
 
 		[Test]
 		public void BuildMyTVApp ()
 		{
-			Build ("MyTVApp");
+			var project_path = GetProjectPath ("MyTVApp");
+			Clean (project_path);
+			var result = DotNet.AssertBuild (project_path);
+			AssertThatLinkerExecuted (result);
 		}
 
 		[Test]
 		public void BuildMyWatchApp ()
 		{
-			Build ("MyWatchApp");
+			var project_path = GetProjectPath ("MyWatchApp");
+			Clean (project_path);
+			var result = DotNet.AssertBuildFailure (project_path);
+			Assert.That (result.StandardOutput.ToString (), Does.Contain ("The specified RuntimeIdentifier 'watchos-x86' is not recognized."), "Missing runtime pack for watchOS");
 		}
 
 		[TestCase ("iOS")]
@@ -48,7 +74,17 @@ namespace Xamarin.Tests {
 		[TestCase ("macOS")]
 		public void BuildMyClassLibrary (string platform)
 		{
-			Build ("MyClassLibrary", platform);
+			var project_path = GetProjectPath ("MyClassLibrary", platform);
+			Clean (project_path);
+			var result = DotNet.AssertBuild (project_path);
+			Assert.That (result.StandardOutput.ToString (), Does.Not.Contain ("Task \"ILLink\""), "Linker executed unexpectedly.");
+		}
+
+		void AssertThatLinkerExecuted (ExecutionResult result)
+		{
+			var output = result.StandardOutput.ToString ();
+			Assert.That (output, Does.Contain ("Building target \"_RunILLink\" completely."), "Linker did not executed as expected.");
+			Assert.That (output, Does.Contain ("Hello SetupStep"), "Custom steps did not run as expected.");
 		}
 	}
 }