Added support for opening binlog on when test build runs

A new `[OpenBuildLog]` can be used to annotate `[Fact]/[Theory]` tests so that
right after a build happens, the automatically generated .binlog is opened using
Process.Start. This will only work if the viewer is installed from http://msbuildlog.com.

The log is not generated unless the attribute is present, so there's no overhead
unless it's used. Also, even if you forget the attribute and commit/push, on
release builds, the attribute is ignored and the log is not launched.

Author: kzu

.gitignore

@@ -26,3 +26,4 @@ log.txt
 test.proj
 *.log
 *.g
+*.binlog

src/Build/NuGet.Build.Packaging.Tests/Builder.NuGetizer.cs

@@ -1,11 +1,13 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Reflection;
 using System.Threading;
 using Microsoft.Build.Execution;
 using Microsoft.Build.Framework;
+using Microsoft.Build.Logging.StructuredLogger;
 using NuGet.Build.Packaging;
 using Xunit;
 using Xunit.Abstractions;
@@ -16,7 +18,13 @@
 /// </summary>
 static partial class Builder
 {
-	public static TargetResult BuildScenario(string scenarioName, object properties = null, string projectName = null, string target = "GetPackageContents", ITestOutputHelper output = null, LoggerVerbosity? verbosity = null)
+	public static TargetResult BuildScenario(
+		string scenarioName, 
+		object properties = null, 
+		string projectName = null, 
+		string target = "GetPackageContents", 
+		ITestOutputHelper output = null, 
+		LoggerVerbosity? verbosity = null)
 	{
 		var scenarioDir = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "Scenarios", scenarioName);
 
@@ -55,16 +63,22 @@ public static TargetResult BuildScenario(string scenarioName, object properties
 			logger = new TestOutputLogger(null);
 		}
 
+		var loggers = OpenBuildLogAttribute.IsActive ?
+			new ILogger[] { logger, new StructuredLogger { Verbosity = verbosity.GetValueOrDefault(), Parameters = scenarioName + ".binlog" } } :
+			new ILogger[] { logger };
+
 		var buildProps = properties?.GetType().GetProperties()
 			.ToDictionary(prop => prop.Name, prop => prop.GetValue(properties).ToString()) 
 			?? new Dictionary<string, string>();
 
 		buildProps[nameof(ThisAssembly.Project.Properties.NuGetRestoreTargets)] = ThisAssembly.Project.Properties.NuGetRestoreTargets;
 		buildProps[nameof(ThisAssembly.Project.Properties.NuGetTargets)] = ThisAssembly.Project.Properties.NuGetTargets;
 
-		return new TargetResult(projectOrSolution, Build(projectOrSolution, target,
-			properties: buildProps,
-			logger: logger), target, logger);
+		var result = Build(projectOrSolution, target, buildProps, loggers);
+		if (OpenBuildLogAttribute.IsActive)
+			Process.Start(scenarioName + ".binlog");
+
+		return new TargetResult(projectOrSolution, result, target, logger);
 	}
 
 	public class TargetResult : ITargetResult
@@ -114,6 +128,58 @@ public override string ToString()
     }
 }
 
+/// <summary>
+/// Declaratively specifies that the .binlog for the build 
+/// should be opened automatically after building a project.
+/// </summary>
+public class OpenBuildLogAttribute : BeforeAfterTestAttribute
+{
+	/// <summary>
+	/// Whether the attribute is active for the current test.
+	/// </summary>
+	public static bool IsActive
+	{
+		get
+		{
+#if DEBUG
+			var data = Thread.GetNamedDataSlot(nameof(OpenBuildLogAttribute));
+			if (data == null)
+				return false;
+
+			return Thread.GetData(data) != null;
+#else
+			return false;
+#endif
+		}
+	}
+
+	public override void Before(MethodInfo methodUnderTest)
+	{
+		// Don't ever set this flag on release builds just in case 
+		// we forget the attribute in a commit ;)
+#if DEBUG
+		var data = Thread.GetNamedDataSlot(nameof(OpenBuildLogAttribute));
+		if (data == null)
+			data = Thread.AllocateNamedDataSlot(nameof(OpenBuildLogAttribute));
+
+		Thread.SetData(data, new object());
+#endif
+
+		base.Before(methodUnderTest);
+	}
+
+	public override void After(MethodInfo methodUnderTest)
+	{
+#if DEBUG
+		var data = Thread.GetNamedDataSlot(nameof(OpenBuildLogAttribute));
+		if (data != null)
+			Thread.SetData(data, null);
+#endif
+
+		base.After(methodUnderTest);
+	}
+}
+
 /// <summary>
 /// Allows declaratively increasing the MSBuild logger verbosity. In 
 /// order to output anything at all, the BuildScenario must be called 

src/Build/NuGet.Build.Packaging.Tests/Builder.cs

@@ -20,7 +20,7 @@ public static partial class Builder
 	const string ToolsVersion = "14.0";
 #endif
 
-	public static BuildResult Build(ProjectInstance project, string targets, Dictionary<string, string> properties = null, ILogger logger = null)
+	public static BuildResult Build(ProjectInstance project, string targets, Dictionary<string, string> properties = null, ILogger[] loggers = null)
 	{
 		properties = properties ?? new Dictionary<string, string>();
 
@@ -42,16 +42,16 @@ public static BuildResult Build(ProjectInstance project, string targets, Diction
 				LogTaskInputs = true,
 			};
 
-			if (logger != null)
-				parameters.Loggers = new[] { logger };
+			if (loggers != null)
+				parameters.Loggers = loggers;
 
 			var result = manager.Build(parameters, request);
 			//manager.ShutdownAllNodes();
 			return result;
 		}
 	}
 
-	public static BuildResult Build(string projectOrSolution, string targets, Dictionary<string, string> properties = null, ILogger logger = null)
+	public static BuildResult Build(string projectOrSolution, string targets, Dictionary<string, string> properties = null, ILogger[] loggers = null)
 	{
 		if (!Path.IsPathRooted(projectOrSolution))
 			projectOrSolution = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, projectOrSolution);
@@ -67,7 +67,7 @@ public static BuildResult Build(string projectOrSolution, string targets, Dictio
 
 		var projectInstance = new ProjectInstance(projectOrSolution, properties, ToolsVersion);
 
-		return Build(projectInstance, targets, properties, logger);
+		return Build(projectInstance, targets, properties, loggers);
 	}
 
 	static void AddSolutionConfiguration(string projectFile, Dictionary<string, string> properties)

src/Build/NuGet.Build.Packaging.Tests/NuGet.Build.Packaging.Tests.csproj

@@ -15,8 +15,9 @@
   <ItemGroup>
     <PackageReference Include="GitInfo" Version="1.1.61" />
     <PackageReference Include="Microsoft.Build" Version="14.3.0" />
+    <PackageReference Include="Microsoft.Build.Logging.StructuredLogger" Version="1.1.168" />
     <PackageReference Include="Microsoft.Build.Tasks.Core" Version="14.3.0" />
-    <PackageReference Include="MSBuilder.Dump" Version="*" />
+    <PackageReference Include="MSBuilder.CodeTaskAssembly" Version="*" />
     <PackageReference Include="MSBuilder.DumpItems" Version="*" />
     <PackageReference Include="MSBuilder.Introspect" Version="*" />
     <PackageReference Include="System.IO.Compression" Version="4.3.0" />
@@ -33,6 +34,7 @@
   <ItemGroup>
 	<None Remove="Scenarios\**\obj\**\*.*;Scenarios\**\bin\**\*.*" />
     <None Remove="App.config" />
+    <None Include="Scenarios\**\*.*proj;Scenarios\**\*.sln" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="App.config">