Add verbose messages around harvesting.

src/wix/WixToolset.Core/HarvestFilesCommand.cs

@@ -57,6 +57,11 @@ private void HarvestFiles(HarvestFilesSymbol harvestFile, IntermediateSection se
                 var included = this.GetWildcardFiles(harvestFile, inclusions);
                 var excluded = this.GetWildcardFiles(harvestFile, exclusions);
 
+                foreach (var excludedFile in excluded)
+                {
+                    this.Messaging.Write(OptimizerVerboses.ExcludedFile(harvestFile.SourceLineNumbers, excludedFile.Path));
+                }
+
                 resolvedFiles = included.Except(excluded, comparer).ToList();
 
                 if (!resolvedFiles.Any())
@@ -90,6 +95,8 @@ private void HarvestFiles(HarvestFilesSymbol harvestFile, IntermediateSection se
 
                         var id = this.ParseHelper.CreateIdentifier("fls", directoryId, name);
 
+                        this.Messaging.Write(OptimizerVerboses.HarvestedFile(harvestFile.SourceLineNumbers, file));
+
                         section.AddSymbol(new FileSymbol(harvestFile.SourceLineNumbers, id)
                         {
                             ComponentRef = id.Id,

src/wix/WixToolset.Core/OptimizerVerboses.cs

@@ -0,0 +1,30 @@
+// Copyright (c) .NET Foundation and contributors. All rights reserved. Licensed under the Microsoft Reciprocal License. See LICENSE.TXT file in the project root for full license information.
+
+namespace WixToolset.Core
+{
+    using WixToolset.Data;
+
+    internal static class OptimizerVerboses
+    {
+        public static Message HarvestedFile(SourceLineNumber sourceLineNumbers, string harvestedFile)
+        {
+            return Message(sourceLineNumbers, Ids.HarvestedFile, "Harvested file: {0}", harvestedFile);
+        }
+
+        public static Message ExcludedFile(SourceLineNumber sourceLineNumbers, string excludedFile)
+        {
+            return Message(sourceLineNumbers, Ids.ExcludedFile, "File excluded from harvesting: {0}", excludedFile);
+        }
+
+        private static Message Message(SourceLineNumber sourceLineNumber, Ids id, string format, params object[] args)
+        {
+            return new Message(sourceLineNumber, MessageLevel.Verbose, (int)id, format, args);
+        }
+
+        public enum Ids
+        {
+            HarvestedFile = 8700,
+            ExcludedFile = 8701,
+        }
+    }
+}

src/wix/test/WixToolsetTest.CoreIntegration/HarvestFilesFixture.cs

@@ -3,6 +3,7 @@
 namespace WixToolsetTest.CoreIntegration
 {
     using System;
+    using System.Collections.Generic;
     using System.Data;
     using System.IO;
     using System.Linq;
@@ -291,6 +292,23 @@ public void CanHarvestFilesInFiveLines()
             Build("PackageFiveLiner.wxs", (msiPath, _) => AssertFileIdsAndTargetPaths(msiPath, expected));
         }
 
+        [Fact]
+        public void CanGetVerboseHarvestingDetails()
+        {
+            Build("Feature.wxs", (_, result) =>
+            {
+                var messages = result.Messages.Select(m => m.Id).Where(i => i >= 8700 && i < 8800);
+                Assert.Equal(new[]
+                {
+                    8701,
+                    8700,
+                    8701,
+                    8700,
+                    8700,
+                }, messages);
+            }, additionalCommandLineArguments: "-v");
+        }
+
         private static void AssertFileIdsAndTargetPaths(string msiPath, string[] expected)
         {
             var pkg = new WixToolset.Dtf.WindowsInstaller.Package.InstallPackage(msiPath,
@@ -301,7 +319,7 @@ private static void AssertFileIdsAndTargetPaths(string msiPath, string[] expecte
             Assert.Equal(sortedExpected, actual);
         }
 
-        private static void Build(string file, Action<string, WixRunnerResult> tester, bool isPackage = true)
+        private static void Build(string file, Action<string, WixRunnerResult> tester, bool isPackage = true, params string[] additionalCommandLineArguments)
         {
             var folder = TestData.Get("TestData", "HarvestFiles");
 
@@ -312,7 +330,7 @@ private static void Build(string file, Action<string, WixRunnerResult> tester, b
                 var binFolder = Path.Combine(baseFolder, "bin");
                 var msiPath = Path.Combine(binFolder, isPackage ? "test.msi" : "test.msm");
 
-                var arguments = new[]
+                var arguments = new List<string>()
                 {
                     "build",
                     Path.Combine(folder, file),
@@ -323,7 +341,12 @@ private static void Build(string file, Action<string, WixRunnerResult> tester, b
                     "-o", msiPath,
                 };
 
-                var result = WixRunner.Execute(arguments);
+                if (additionalCommandLineArguments.Length > 0)
+                {
+                    arguments.AddRange(additionalCommandLineArguments);
+                }
+
+                var result = WixRunner.Execute(arguments.ToArray());
 
                 tester(msiPath, result);
             }