Enhance the update-dependencies script:

- Add the new version number to the commit and PR message.
- Check if anything has been updated and no-op if there wasn't anything updated.
- Add support to CC indviduals on the PR.

scripts/update-dependencies/PushPRTargets.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System;
+using System.Linq;
 using Microsoft.DotNet.Cli.Build.Framework;
 using Octokit;
 
@@ -14,8 +15,6 @@ namespace Microsoft.DotNet.Scripts
     /// </summary>
     public static class PushPRTargets
     {
-        private const string PullRequestTitle = "Updating dependencies from last known good builds";
-
         private static readonly Config s_config = Config.Instance;
 
         [Target(nameof(CommitChanges), nameof(CreatePR))]
@@ -28,14 +27,31 @@ namespace Microsoft.DotNet.Scripts
         [Target]
         public static BuildTargetResult CommitChanges(BuildTargetContext c)
         {
-            Cmd("git", "add", ".")
-                .Execute()
-                .EnsureSuccessful();
+            CommandResult statusResult = Cmd("git", "status", "--porcelain")
+                .CaptureStdOut()
+                .Execute();
+            statusResult.EnsureSuccessful();
+
+            bool hasModifiedFiles = !string.IsNullOrWhiteSpace(statusResult.StdOut);
+            bool hasUpdatedDependencies = c.GetDependencyInfos().Where(d => d.IsUpdated).Any();
+
+            if (hasModifiedFiles != hasUpdatedDependencies)
+            {
+                return c.Failed($"'git status' does not match DependencyInfo information. Git has modified files: {hasModifiedFiles}. DependencyInfo is updated: {hasUpdatedDependencies}.");
+            }
+
+            if (!hasUpdatedDependencies)
+            {
+                c.Warn("Dependencies are currently up to date");
+                return c.Success();
+            }
 
             string userName = s_config.UserName;
             string email = s_config.Email;
 
-            Cmd("git", "commit", "-m", PullRequestTitle, "--author", $"{userName} <{email}>")
+            string commitMessage = GetCommitMessage(c);
+
+            Cmd("git", "commit", "-a", "-m", commitMessage, "--author", $"{userName} <{email}>")
                 .EnvironmentVariable("GIT_COMMITTER_NAME", userName)
                 .EnvironmentVariable("GIT_COMMITTER_EMAIL", email)
                 .Execute()
@@ -79,12 +95,19 @@ namespace Microsoft.DotNet.Scripts
         public static BuildTargetResult CreatePR(BuildTargetContext c)
         {
             string remoteBranchName = c.GetRemoteBranchName();
+            string commitMessage = c.GetCommitMessage();
 
             NewPullRequest prInfo = new NewPullRequest(
-                PullRequestTitle,
+                commitMessage,
                 s_config.GitHubOriginOwner + ":" + remoteBranchName,
                 s_config.GitHubUpstreamBranch);
 
+            string[] prNotifications = s_config.GitHubPullRequestNotifications;
+            if (prNotifications.Length > 0)
+            {
+                prInfo.Body = $"/cc @{string.Join(" @", prNotifications)}";
+            }
+
             GitHubClient gitHub = new GitHubClient(new ProductHeaderValue("dotnetDependencyUpdater"));
 
             gitHub.Credentials = new Credentials(s_config.Password);
@@ -104,5 +127,36 @@ namespace Microsoft.DotNet.Scripts
         {
             c.BuildContext["RemoteBranchName"] = value;
         }
+
+        private static string GetCommitMessage(this BuildTargetContext c)
+        {
+            const string commitMessagePropertyName = "CommitMessage";
+
+            string message;
+            object messageObject;
+            if (c.BuildContext.Properties.TryGetValue(commitMessagePropertyName, out messageObject))
+            {
+                message = (string)messageObject;
+            }
+            else
+            {
+                DependencyInfo[] updatedDependencies = c.GetDependencyInfos()
+                    .Where(d => d.IsUpdated)
+                    .ToArray();
+
+                string updatedDependencyNames = string.Join(", ", updatedDependencies.Select(d => d.Name));
+                string updatedDependencyVersions = string.Join(", ", updatedDependencies.Select(d => d.NewReleaseVersion));
+
+                message = $"Updating {updatedDependencyNames} to {updatedDependencyVersions}";
+                if (updatedDependencies.Count() > 1)
+                {
+                    message += " respectively";
+                }
+
+                c.BuildContext[commitMessagePropertyName] = message;
+            }
+
+            return message;
+        }
     }
 }