Add better errors, fix help output text, and add 'dotnet watch --list' to help us diagnose issues

Fixes #252 - help output shown twice in dotnet-watch
Fixes #250 - add dotnet-watch --list. Prints a list of all files discovered
Fixes #249 - better error message when GenerateWatchList fails

.editorconfig

@@ -0,0 +1,28 @@
+; EditorConfig to support per-solution formatting.
+; Use the EditorConfig VS add-in to make this work.
+; http://editorconfig.org/
+
+; This is the default for the codeline.
+root = true
+
+[*]
+indent_style = space
+charset = utf-8
+trim_trailing_whitespace = true
+
+[*.{cs}]
+indent_size = 4
+insert_final_newline = true
+
+; All XML-based file formats
+[*.{config,csproj,nuspec,props,resx,targets,xml}]
+indent_size = 2
+
+[*.{json}]
+indent_size = 2
+
+[*.{ps1}]
+indent_size = 4
+
+[*.{sh}]
+indent_size = 4

DotNetTools.sln

@@ -1,6 +1,6 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 15
-VisualStudioVersion = 15.0.25807.0
+VisualStudioVersion = 15.0.26020.0
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{66517987-2A5A-4330-B130-207039378FD4}"
 EndProject
@@ -8,6 +8,7 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Microsoft.DotNet.Watcher.To
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{8321E0D1-9A47-4D2F-AED8-3AE636D44E35}"
 	ProjectSection(SolutionItems) = preProject
+		.editorconfig = .editorconfig
 		NuGet.Config = NuGet.Config
 	EndProjectSection
 EndProject
@@ -43,10 +44,6 @@ Global
 		{8730E848-CA0F-4E0A-9A2F-BC22AD0B2C4E}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{8730E848-CA0F-4E0A-9A2F-BC22AD0B2C4E}.Release|Any CPU.ActiveCfg = Debug|Any CPU
 		{8730E848-CA0F-4E0A-9A2F-BC22AD0B2C4E}.Release|Any CPU.Build.0 = Debug|Any CPU
-		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Release|Any CPU.ActiveCfg = Debug|Any CPU
-		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Release|Any CPU.Build.0 = Debug|Any CPU
 		{7B331122-83B1-4F08-A119-DC846959844C}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{7B331122-83B1-4F08-A119-DC846959844C}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{7B331122-83B1-4F08-A119-DC846959844C}.Release|Any CPU.ActiveCfg = Debug|Any CPU
@@ -59,6 +56,10 @@ Global
 		{53F3B53D-303A-4DAA-9C38-4F55195FA5B9}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{53F3B53D-303A-4DAA-9C38-4F55195FA5B9}.Release|Any CPU.ActiveCfg = Debug|Any CPU
 		{53F3B53D-303A-4DAA-9C38-4F55195FA5B9}.Release|Any CPU.Build.0 = Debug|Any CPU
+		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Release|Any CPU.ActiveCfg = Debug|Any CPU
+		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD}.Release|Any CPU.Build.0 = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -67,9 +68,9 @@ Global
 		{8A8CEABC-AC47-43FF-A5DF-69224F7E1F46} = {66517987-2A5A-4330-B130-207039378FD4}
 		{16BADE2F-1184-4518-8A70-B68A19D0805B} = {F5B382BC-258F-46E1-AC3D-10E5CCD55134}
 		{8730E848-CA0F-4E0A-9A2F-BC22AD0B2C4E} = {66517987-2A5A-4330-B130-207039378FD4}
-		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD} = {F5B382BC-258F-46E1-AC3D-10E5CCD55134}
 		{7B331122-83B1-4F08-A119-DC846959844C} = {F5B382BC-258F-46E1-AC3D-10E5CCD55134}
 		{8A2E6961-6B12-4A8E-8215-3E7301D52EAC} = {F5B382BC-258F-46E1-AC3D-10E5CCD55134}
 		{53F3B53D-303A-4DAA-9C38-4F55195FA5B9} = {66517987-2A5A-4330-B130-207039378FD4}
+		{9295E811-FF0F-E40A-2F9A-0B2C4EBC22AD} = {F5B382BC-258F-46E1-AC3D-10E5CCD55134}
 	EndGlobalSection
 EndGlobal

src/Microsoft.DotNet.Watcher.Tools/CommandLineOptions.cs

@@ -16,6 +16,7 @@ namespace Microsoft.DotNet.Watcher
         public bool IsQuiet { get; private set; }
         public bool IsVerbose { get; private set; }
         public IList<string> RemainingArguments { get; private set; }
+        public bool ListFiles { get; private set; }
 
         public static CommandLineOptions Parse(string[] args, IConsole console)
         {
@@ -63,6 +64,9 @@ Examples:
                 CommandOptionType.NoValue);
             var optVerbose = app.VerboseOption();
 
+            var optList = app.Option("--list", "Lists all discovered files without starting the watcher",
+                CommandOptionType.NoValue);
+
             app.VersionOptionFromAssemblyAttributes(typeof(Program).GetTypeInfo().Assembly);
 
             if (app.Execute(args) != 0)
@@ -75,7 +79,9 @@ Examples:
                 throw new CommandParsingException(app, Resources.Error_QuietAndVerboseSpecified);
             }
 
-            if (app.RemainingArguments.Count == 0)
+            if (app.RemainingArguments.Count == 0
+                && !app.IsShowingInformation
+                && !optList.HasValue())
             {
                 app.ShowHelp();
             }
@@ -86,8 +92,9 @@ Examples:
                 IsQuiet = optQuiet.HasValue(),
                 IsVerbose = optVerbose.HasValue(),
                 RemainingArguments = app.RemainingArguments,
-                IsHelp = app.IsShowingInformation
+                IsHelp = app.IsShowingInformation,
+                ListFiles = optList.HasValue(),
             };
         }
     }
-}
+}

src/Microsoft.DotNet.Watcher.Tools/DotNetWatcher.cs

@@ -34,6 +34,13 @@ namespace Microsoft.DotNet.Watcher
             while (true)
             {
                 var fileSet = await fileSetFactory.CreateAsync(cancellationToken);
+
+                if (fileSet == null)
+                {
+                    _reporter.Error("Failed to find a list of files to watch");
+                    return;
+                }
+
                 if (cancellationToken.IsCancellationRequested)
                 {
                     return;
@@ -91,4 +98,4 @@ namespace Microsoft.DotNet.Watcher
             }
         }
     }
-}
+}

src/Microsoft.DotNet.Watcher.Tools/Internal/MsBuildFileSetFactory.cs

@@ -16,17 +16,19 @@ namespace Microsoft.DotNet.Watcher.Internal
     public class MsBuildFileSetFactory : IFileSetFactory
     {
         private const string TargetName = "GenerateWatchList";
-        private const string ProjectExtensionFileExtension = ".dotnetwatch.targets";
+        private const string ProjectExtensionFileExtension = ".dotnetwatch.g.targets";
         private const string WatchTargetsFileName = "DotNetWatchCommon.targets";
         private readonly IReporter _reporter;
         private readonly string _projectFile;
         private readonly string _watchTargetsDir;
         private readonly OutputSink _outputSink;
         private readonly ProcessRunner _processRunner;
+        private readonly bool _waitOnError;
 
-        public MsBuildFileSetFactory(IReporter reporter, string projectFile)
+        public MsBuildFileSetFactory(IReporter reporter, string projectFile, bool waitOnError)
             : this(reporter, projectFile, new OutputSink())
         {
+            _waitOnError = waitOnError;
         }
 
         // output sink is for testing
@@ -86,7 +88,7 @@ namespace Microsoft.DotNet.Watcher.Internal
 
                     var exitCode = await _processRunner.RunAsync(processSpec, cancellationToken);
 
-                    if (exitCode == 0)
+                    if (exitCode == 0 && File.Exists(watchList))
                     {
                         var fileset = new FileSet(
                             File.ReadAllLines(watchList)
@@ -109,28 +111,41 @@ namespace Microsoft.DotNet.Watcher.Internal
 
                     _reporter.Error($"Error(s) finding watch items project file '{Path.GetFileName(_projectFile)}'");
 
-                    _reporter.Output($"MSBuild output from target '{TargetName}'");
+                    _reporter.Output($"MSBuild output from target '{TargetName}':");
+                    _reporter.Output(string.Empty);
 
                     foreach (var line in capture.Lines)
                     {
-                        _reporter.Output($"  [MSBUILD] : {line}");
+                        _reporter.Output($"   {line}");
                     }
 
-                    _reporter.Warn("Fix the error to continue or press Ctrl+C to exit.");
+                    _reporter.Output(string.Empty);
 
-                    var fileSet = new FileSet(new[] {_projectFile});
+                    if (!_waitOnError)
-
-                    using (var watcher = new FileSetWatcher(fileSet))
                     {
-                        await watcher.GetChangedFileAsync(cancellationToken);
+                        return null;
+                    }
+                    else
+                    {
+                        _reporter.Warn("Fix the error to continue or press Ctrl+C to exit.");
 
-                        _reporter.Output($"File changed: {_projectFile}");
+                        var fileSet = new FileSet(new[] { _projectFile });
+
+                        using (var watcher = new FileSetWatcher(fileSet))
+                        {
+                            await watcher.GetChangedFileAsync(cancellationToken);
+
+                            _reporter.Output($"File changed: {_projectFile}");
+                        }
                     }
                 }
             }
             finally
             {
-                File.Delete(watchList);
+                if (File.Exists(watchList))
+                {
+                    File.Delete(watchList);
+                }
             }
         }
 
@@ -173,4 +188,4 @@ namespace Microsoft.DotNet.Watcher.Internal
             return Path.GetDirectoryName(targetPath);
         }
     }
-}
+}

src/Microsoft.DotNet.Watcher.Tools/Program.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -80,7 +80,20 @@ namespace Microsoft.DotNet.Watcher
 
                 try
                 {
-                    return await MainInternalAsync(reporter, options.Project, options.RemainingArguments, ctrlCTokenSource.Token);
+                    if (options.ListFiles)
+                    {
+                        return await ListFilesAsync(reporter,
+                            options.Project,
+                            ctrlCTokenSource.Token);
+                    }
+                    else
+                    {
+
+                        return await MainInternalAsync(reporter,
+                            options.Project,
+                            options.RemainingArguments,
+                            ctrlCTokenSource.Token);
+                    }
                 }
                 catch (Exception ex)
                 {
@@ -115,8 +128,7 @@ namespace Microsoft.DotNet.Watcher
                 return 1;
             }
 
-            var fileSetFactory = new MsBuildFileSetFactory(reporter, projectFile);
+            var fileSetFactory = new MsBuildFileSetFactory(reporter, projectFile, waitOnError: true);
-
             var processInfo = new ProcessSpec
             {
                 Executable = DotNetMuxer.MuxerPathOrDefault(),
@@ -130,6 +142,39 @@ namespace Microsoft.DotNet.Watcher
             return 0;
         }
 
+        private async Task<int> ListFilesAsync(
+            IReporter reporter,
+            string project,
+            CancellationToken cancellationToken)
+        {
+            // TODO multiple projects should be easy enough to add here
+            string projectFile;
+            try
+            {
+                projectFile = MsBuildProjectFinder.FindMsBuildProject(_workingDir, project);
+            }
+            catch (FileNotFoundException ex)
+            {
+                reporter.Error(ex.Message);
+                return 1;
+            }
+
+            var fileSetFactory = new MsBuildFileSetFactory(reporter, projectFile, waitOnError: false);
+            var files = await fileSetFactory.CreateAsync(cancellationToken);
+
+            if (files == null)
+            {
+                return 1;
+            }
+
+            foreach (var file in files)
+            {
+                _console.Out.WriteLine(file);
+            }
+
+            return 0;
+        }
+
         private static IReporter CreateReporter(bool verbose, bool quiet, IConsole console)
         {
             const string prefix = "watch : ";
@@ -178,4 +223,4 @@ namespace Microsoft.DotNet.Watcher
                 .Build();
         }
     }
-}
+}

src/Microsoft.Extensions.SecretManager.Tools/Internal/ProjectIdResolver.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
@@ -98,9 +98,7 @@ namespace Microsoft.Extensions.SecretManager.Tools.Internal
             // running tool
             using (var resource = GetType().GetTypeInfo().Assembly.GetManifestResourceStream("ProjectIdResolverTargets.xml"))
             using (var stream = new FileStream(projectExtensionsPath, FileMode.Create))
-            using (var writer = new StreamWriter(stream))
             {
-                writer.WriteLine("<!-- Auto-generated by dotnet-user-secrets. This file can be deleted and should not be commited to source control. -->");
                 resource.CopyTo(stream);
             }
         }
@@ -120,4 +118,4 @@ namespace Microsoft.Extensions.SecretManager.Tools.Internal
             }
         }
     }
-}
+}

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/AppWithDepsTests.cs

@@ -22,7 +22,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task ChangeFileInDependency()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var fileToChange = Path.Combine(_app.DependencyFolder, "Foo.cs");
             var programCs = File.ReadAllText(fileToChange);

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/AwaitableProcess.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
 using System.Text;
@@ -9,8 +10,8 @@ using System.Threading;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Dataflow;
 using Microsoft.Extensions.Internal;
-using Xunit.Abstractions;
 using Microsoft.Extensions.Tools.Internal;
+using Xunit.Abstractions;
 
 namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
 {
@@ -71,6 +72,21 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
             return null;
         }
 
+        public async Task<IList<string>> GetAllOutputLines()
+        {
+            var lines = new List<string>();
+            while (!_source.Completion.IsCompleted)
+            {
+                while (await _source.OutputAvailableAsync())
+                {
+                    var next = await _source.ReceiveAsync();
+                    _logger.WriteLine($"{DateTime.Now}: recv: '{next}'");
+                    lines.Add(next);
+                }
+            }
+            return lines;
+        }
+
         private void StartProcessingOutput(StreamReader streamReader)
         {
             _source = _source ?? new BufferBlock<string>();
@@ -80,7 +96,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
                 string line;
                 while ((line = streamReader.ReadLine()) != null)
                 {
-                    _logger.WriteLine($"{DateTime.Now} post: {line}");
+                    _logger.WriteLine($"{DateTime.Now}: post: '{line}'");
                     _source.Post(line);
                 }
 

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/GlobbingAppTests.cs

@@ -5,6 +5,7 @@ using System;
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
+using Microsoft.DotNet.Watcher.Tools.Tests;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -24,7 +25,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [InlineData(false)]
         public async Task ChangeCompiledFile(bool usePollingWatcher)
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var types = await _app.GetCompiledAppDefinedTypes().OrTimeout();
             Assert.Equal(2, types);
@@ -41,7 +42,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact(Skip = "Broken. See https://github.com/aspnet/DotNetTools/issues/212")]
         public async Task AddCompiledFile()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var types = await _app.GetCompiledAppDefinedTypes().OrTimeout();
             Assert.Equal(2, types);
@@ -57,7 +58,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task DeleteCompiledFile()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var types = await _app.GetCompiledAppDefinedTypes().OrTimeout();
             Assert.Equal(2, types);
@@ -73,7 +74,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task DeleteSourceFolder()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var types = await _app.GetCompiledAppDefinedTypes().OrTimeout();
             Assert.Equal(2, types);
@@ -89,7 +90,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task RenameCompiledFile()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var oldFile = Path.Combine(_app.SourceDirectory, "include", "Foo.cs");
             var newFile = Path.Combine(_app.SourceDirectory, "include", "Foo_new.cs");
@@ -101,7 +102,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task ChangeExcludedFile()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
 
             var changedFile = Path.Combine(_app.SourceDirectory, "exclude", "Baz.cs");
             File.WriteAllText(changedFile, "");
@@ -111,6 +112,23 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
             Assert.NotSame(restart, finished);
         }
 
+        [Fact]
+        public async Task ListsFiles()
+        {
+            _app.Start(new [] { "--list" });
+            var lines = await _app.Process.GetAllOutputLines();
+
+            AssertEx.EqualFileList(
+                _app.Scenario.WorkFolder,
+                new[]
+                {
+                    "GlobbingApp/Program.cs",
+                    "GlobbingApp/include/Foo.cs",
+                    "GlobbingApp/GlobbingApp.csproj",
+                },
+                lines);
+        }
+
         public void Dispose()
         {
             _app.Dispose();

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/NoDepsAppTests.cs

@@ -23,7 +23,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task RestartProcessOnFileChange()
         {
-            await _app.StartWatcher(new[] { "--no-exit" }).OrTimeout();
+            await _app.StartWatcherAsync(new[] { "--no-exit" }).OrTimeout();
             var pid = await _app.GetProcessId().OrTimeout();
 
             // Then wait for it to restart when we change a file
@@ -42,7 +42,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         [Fact]
         public async Task RestartProcessThatTerminatesAfterFileChange()
         {
-            await _app.StartWatcher().OrTimeout();
+            await _app.StartWatcherAsync().OrTimeout();
             var pid = await _app.GetProcessId().OrTimeout();
             await _app.HasExited().OrTimeout(); // process should exit after run
 

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/Scenario/ProjectToolScenario.cs

@@ -118,17 +118,17 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
             // this launches a new .NET Core process using the runtime of the current test app
             // and the version of dotnet-watch that this test app is compiled against
             var thisAssembly = Path.GetFileNameWithoutExtension(GetType().GetTypeInfo().Assembly.Location);
-            var args = new List<string>();
-            args.Add("exec");
 
-            args.Add("--depsfile");
+            var args = new List<string>
-            args.Add(Path.Combine(AppContext.BaseDirectory, thisAssembly + ".deps.json"));
+            {
+                "exec",
+                "--depsfile",
+                Path.Combine(AppContext.BaseDirectory, thisAssembly + ".deps.json"),
+                "--runtimeconfig",
+                Path.Combine(AppContext.BaseDirectory, thisAssembly + ".runtimeconfig.json")
+            };
 
-            args.Add("--runtimeconfig");
+            if (AppContext.GetData("FX_DEPS_FILE") is string currentFxVersion)
-            args.Add(Path.Combine(AppContext.BaseDirectory, thisAssembly + ".runtimeconfig.json"));
-
-            var currentFxVersion = AppContext.GetData("FX_DEPS_FILE") as string;
-            if (currentFxVersion != null)
             {
                 // This overrides the version of shared fx in the runtimeconfig.json file.
                 // Tests do this to ensure dotnet-watch is executing on the version of Microsoft.NETCore.App

test/Microsoft.DotNet.Watcher.Tools.FunctionalTests/Scenario/WatchableApp.cs

@@ -1,12 +1,13 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using Microsoft.Extensions.Tools.Internal;
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
+using Microsoft.Extensions.Tools.Internal;
 using Xunit.Abstractions;
 
 namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
@@ -16,12 +17,11 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
         private const string StartedMessage = "Started";
         private const string ExitingMessage = "Exiting";
 
-        protected ProjectToolScenario Scenario { get; }
         private readonly ITestOutputHelper _logger;
-        protected AwaitableProcess Process { get; set; }
         private string _appName;
         private bool _prepared;
 
+
         public WatchableApp(string appName, ITestOutputHelper logger)
         {
             _logger = logger;
@@ -31,6 +31,10 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
             SourceDirectory = Path.Combine(Scenario.WorkFolder, appName);
         }
 
+        public ProjectToolScenario Scenario { get; }
+
+        public AwaitableProcess Process { get; protected set; }
+
         public string SourceDirectory { get; }
 
         public Task HasRestarted()
@@ -41,9 +45,6 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
 
         public bool UsePollingWatcher { get; set; }
 
-        public Task StartWatcher([CallerMemberName] string name = null)
-            => StartWatcher(Array.Empty<string>(), name);
-
         public async Task<int> GetProcessId()
         {
             var line = await Process.GetOutputLineAsync(l => l.StartsWith("PID ="));
@@ -58,7 +59,7 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
             _prepared = true;
         }
 
-        public async Task StartWatcher(string[] arguments, [CallerMemberName] string name = null)
+        public void Start(IEnumerable<string> arguments, [CallerMemberName] string name = null)
         {
             if (!_prepared)
             {
@@ -67,7 +68,6 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
 
             var args = Scenario
                 .GetDotnetWatchArguments()
-                .Concat(new[] { "run", "--" })
                 .Concat(arguments);
 
             var spec = new ProcessSpec
@@ -79,6 +79,15 @@ namespace Microsoft.DotNet.Watcher.Tools.FunctionalTests
 
             Process = new AwaitableProcess(spec, _logger);
             Process.Start();
+        }
+
+        public Task StartWatcherAsync([CallerMemberName] string name = null)
+            => StartWatcherAsync(Array.Empty<string>(), name);
+
+        public async Task StartWatcherAsync(string[] arguments, [CallerMemberName] string name = null)
+        {
+            var args = new[] { "run", "--" }.Concat(arguments);
+            Start(args, name);
             await Process.GetOutputLineAsync(StartedMessage);
         }
 

test/Microsoft.DotNet.Watcher.Tools.Tests/MsBuildFileSetFactoryTest.cs

@@ -297,7 +297,8 @@ namespace Microsoft.DotNet.Watcher.Tools.Tests
         }
 
         private Task<IFileSet> GetFileSet(TemporaryCSharpProject target)
-            => GetFileSet(new MsBuildFileSetFactory(_reporter, target.Path));
+            => GetFileSet(new MsBuildFileSetFactory(_reporter, target.Path, waitOnError: false));
+
         private async Task<IFileSet> GetFileSet(MsBuildFileSetFactory filesetFactory)
         {
             _tempDir.Create();
@@ -305,6 +306,7 @@ namespace Microsoft.DotNet.Watcher.Tools.Tests
             var finished = await Task.WhenAny(createTask, Task.Delay(TimeSpan.FromSeconds(10)));
 
             Assert.Same(createTask, finished);
+            Assert.NotNull(createTask.Result);
             return createTask.Result;
         }