Support tree structure when updating stack

src/Stack.Tests/Commands/Helpers/StackHelpersTests.cs

@@ -162,7 +162,7 @@ public void UpdateStackUsingRebase_WhenARemoteBranchIsDeleted_RebasesOntoThePare
             "Stack1",
             Some.HttpsUri().ToString(),
             sourceBranch,
-            [new Config.Branch(branch1, []), new Config.Branch(branch2, [])]
+            [new Config.Branch(branch1, [new Config.Branch(branch2, [])])]
         );
         var stackStatus = StackHelpers.GetStackStatus(stack, branch1, logger, gitClient, gitHubClient, false);
 
@@ -238,7 +238,7 @@ public void UpdateStackUsingRebase_WhenARemoteBranchIsDeleted_ButTheTargetBranch
             "Stack1",
             Some.HttpsUri().ToString(),
             sourceBranch,
-            [new Config.Branch(branch1, []), new Config.Branch(branch2, [])]
+            [new Config.Branch(branch1, [new Config.Branch(branch2, [])])]
         );
         var stackStatus = StackHelpers.GetStackStatus(stack, branch1, logger, gitClient, gitHubClient, false);
 
@@ -292,7 +292,7 @@ public void UpdateStackUsingRebase_WhenARemoteBranchIsDeleted_AndLocalBranchIsDe
             "Stack1",
             Some.HttpsUri().ToString(),
             sourceBranch,
-            [new Config.Branch(branch1, []), new Config.Branch(branch2, [])]
+            [new Config.Branch(branch1, [new Config.Branch(branch2, [])])]
         );
         var stackStatus = StackHelpers.GetStackStatus(stack, branch1, logger, gitClient, gitHubClient, false);
 
@@ -306,4 +306,132 @@ public void UpdateStackUsingRebase_WhenARemoteBranchIsDeleted_AndLocalBranchIsDe
         var fileContents = File.ReadAllText(Path.Join(repo.LocalDirectoryPath, changedFile2Path));
         fileContents.Should().Be(changedFile2Contents);
     }
+
+    [Fact]
+    public void UpdateStackUsingRebase_WhenStackHasATreeStructure_RebasesAllBranchesCorrectly()
+    {
+        // Arrange
+        var sourceBranch = "source-branch";
+        var branch1 = "branch-1";
+        var branch2 = "branch-2";
+        var branch3 = "branch-3";
+        var changedFilePath = "change-file-1";
+        var commit1ChangedFileContents = "These are the changes in the first commit";
+
+        using var repo = new TestGitRepositoryBuilder()
+            .WithBranch(b => b
+                .WithName(sourceBranch)
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch1)
+                .FromSourceBranch(sourceBranch)
+                .WithCommit(c => c.WithChanges("file-1", "file-1-changes"))
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch2)
+                .FromSourceBranch(branch1)
+                .WithCommit(c => c.WithChanges("file-2", "file-2-changes"))
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch3)
+                .FromSourceBranch(branch1)
+                .WithCommit(c => c.WithChanges("file-3", "file-3-changes"))
+                .PushToRemote())
+            .Build();
+
+        var inputProvider = Substitute.For<IInputProvider>();
+        var gitClient = new GitClient(new TestLogger(testOutputHelper), repo.GitClientSettings);
+        var logger = new TestLogger(testOutputHelper);
+        var gitHubClient = Substitute.For<IGitHubClient>();
+
+        gitClient.ChangeBranch(sourceBranch);
+        File.WriteAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath), commit1ChangedFileContents);
+        repo.Stage(changedFilePath);
+        repo.Commit();
+        repo.Push(sourceBranch);
+
+        var stack = new Config.Stack(
+            "Stack1",
+            Some.HttpsUri().ToString(),
+            sourceBranch,
+            [new Config.Branch(branch1, [new Config.Branch(branch2, []), new Config.Branch(branch3, [])])]
+        );
+        var stackStatus = StackHelpers.GetStackStatus(stack, sourceBranch, logger, gitClient, gitHubClient, false);
+
+        // Act
+        StackHelpers.UpdateStackUsingRebase(stack, stackStatus, gitClient, inputProvider, logger);
+
+        // Assert
+        gitClient.ChangeBranch(branch2);
+        var branch2FileContents = File.ReadAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath));
+        branch2FileContents.Should().Be(commit1ChangedFileContents);
+
+        gitClient.ChangeBranch(branch3);
+        var branch3FileContents = File.ReadAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath));
+        branch3FileContents.Should().Be(commit1ChangedFileContents);
+    }
+
+    [Fact]
+    public void UpdateStackUsingMerge_WhenStackHasATreeStructure_MergesAllBranchesCorrectly()
+    {
+        // Arrange
+        var sourceBranch = "source-branch";
+        var branch1 = "branch-1";
+        var branch2 = "branch-2";
+        var branch3 = "branch-3";
+        var changedFilePath = "change-file-1";
+        var commit1ChangedFileContents = "These are the changes in the first commit";
+
+        using var repo = new TestGitRepositoryBuilder()
+            .WithBranch(b => b
+                .WithName(sourceBranch)
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch1)
+                .FromSourceBranch(sourceBranch)
+                .WithCommit(c => c.WithChanges("file-1", "file-1-changes"))
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch2)
+                .FromSourceBranch(branch1)
+                .WithCommit(c => c.WithChanges("file-2", "file-2-changes"))
+                .PushToRemote())
+            .WithBranch(b => b
+                .WithName(branch3)
+                .FromSourceBranch(branch1)
+                .WithCommit(c => c.WithChanges("file-3", "file-3-changes"))
+                .PushToRemote())
+            .Build();
+
+        var inputProvider = Substitute.For<IInputProvider>();
+        var gitClient = new GitClient(new TestLogger(testOutputHelper), repo.GitClientSettings);
+        var logger = new TestLogger(testOutputHelper);
+        var gitHubClient = Substitute.For<IGitHubClient>();
+
+        gitClient.ChangeBranch(sourceBranch);
+        File.WriteAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath), commit1ChangedFileContents);
+        repo.Stage(changedFilePath);
+        repo.Commit();
+        repo.Push(sourceBranch);
+
+        var stack = new Config.Stack(
+            "Stack1",
+            Some.HttpsUri().ToString(),
+            sourceBranch,
+            [new Config.Branch(branch1, [new Config.Branch(branch2, []), new Config.Branch(branch3, [])])]
+        );
+        var stackStatus = StackHelpers.GetStackStatus(stack, sourceBranch, logger, gitClient, gitHubClient, false);
+
+        // Act
+        StackHelpers.UpdateStackUsingMerge(stack, stackStatus, gitClient, inputProvider, logger);
+
+        // Assert
+        gitClient.ChangeBranch(branch2);
+        var branch2FileContents = File.ReadAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath));
+        branch2FileContents.Should().Be(commit1ChangedFileContents);
+
+        gitClient.ChangeBranch(branch3);
+        var branch3FileContents = File.ReadAllText(Path.Join(repo.LocalDirectoryPath, changedFilePath));
+        branch3FileContents.Should().Be(commit1ChangedFileContents);
+    }
 }

src/Stack.Tests/Config/StackTests.cs

@@ -7,6 +7,49 @@ namespace Stack.Tests;
 
 public class StackTests
 {
+    [Fact]
+    public void GetAllBranchLines_ReturnsAllRootToLeafPaths()
+    {
+        // Arrange: Build a stack with the following structure:
+        // - A
+        //   - B
+        //     - C
+        //     - D
+        //   - E
+        //   - F
+        //     - G
+        var stack = new Config.Stack(
+            "TestStack",
+            Some.HttpsUri().ToString(),
+            "main",
+            [
+                new Config.Branch("A", [
+                    new Config.Branch("B", [
+                        new Config.Branch("C", []),
+                        new Config.Branch("D", [])
+                    ]),
+                    new Config.Branch("E", []),
+                    new Config.Branch("F", [
+                        new Config.Branch("G", [])
+                    ])
+                ])
+            ]
+        );
+
+        // Act
+        var lines = stack.GetAllBranchLines();
+
+        // Assert: Should match the expected root-to-leaf paths (by branch name)
+        var branchNameLines = lines.Select(line => line.Select(b => b.Name).ToArray()).ToList();
+        branchNameLines.Should().BeEquivalentTo<string[]>(
+        [
+            ["A", "B", "C"],
+            ["A", "B", "D"],
+            ["A", "E"],
+            ["A", "F", "G"]
+        ], options => options.WithStrictOrdering());
+    }
+
     [Fact]
     public void GetDefaultBranchName_WhenNoBranchesInStack_ShouldReturnBranchNameWithTheNumber1AtTheEnd_BecauseItIsTheFirstBranch()
     {

src/Stack.Tests/Helpers/TestGitRepositoryBuilder.cs

@@ -1,3 +1,4 @@
+using System.Text;
 using LibGit2Sharp;
 using Stack.Git;
 
@@ -84,13 +85,8 @@ public class CommitBuilder
 {
     Func<Repository, string>? getBranchName;
     string? message;
-    string? authorName;
-    string? authorEmail;
-    string? committerName;
-    string? committerEmail;
-    bool allowEmptyCommit;
     bool pushToRemote;
-    List<(string Path, string Contents)> changes = [];
+    List<(string Path, string? Contents)> changes = [];
 
     public CommitBuilder OnBranch(string branch)
     {
@@ -116,26 +112,6 @@ public CommitBuilder WithMessage(string message)
         return this;
     }
 
-    public CommitBuilder WithAuthor(string name, string email)
-    {
-        authorName = name;
-        authorEmail = email;
-        return this;
-    }
-
-    public CommitBuilder WithCommitter(string name, string email)
-    {
-        committerName = name;
-        committerEmail = email;
-        return this;
-    }
-
-    public CommitBuilder AllowEmptyCommit()
-    {
-        allowEmptyCommit = true;
-        return this;
-    }
-
     public CommitBuilder PushToRemote()
     {
         pushToRemote = true;
@@ -152,29 +128,80 @@ public void Build(Repository repository)
             branch = repository.Branches[branchName];
         }
 
-        if (branch is not null)
+        var signature = new Signature(Some.Name(), Some.Name(), DateTimeOffset.Now);
+
+        Commit(repository, branch?.Tip, branch?.CanonicalName, message ?? Some.Name(), signature, changes.ToArray());
+
+        if (branch is not null && pushToRemote)
         {
-            repository.Refs.UpdateTarget("HEAD", branch.CanonicalName);
+            repository.Network.Push(branch);
         }
+    }
 
-        foreach (var (path, contents) in changes)
+    public static LibGit2Sharp.Commit Commit(Repository repository,
+        LibGit2Sharp.Commit? parent,
+        string? branchName,
+        string message,
+        Signature? signature,
+        params (string Name, string? Content)[] files)
+    {
+        // Commits for uninitialised repositories will have no parent, and will need to start with an empty tree.
+        var treeDefinition = parent is null ? new TreeDefinition() : TreeDefinition.From(parent.Tree);
+
+        foreach (var file in files)
         {
-            var fullPath = Path.Combine(repository.Info.WorkingDirectory, path);
-            var directory = Path.GetDirectoryName(fullPath);
-            Directory.CreateDirectory(directory!);
-            File.WriteAllText(fullPath, contents);
-            LibGit2Sharp.Commands.Stage(repository, path);
+            if (file.Content is null)
+            {
+                treeDefinition.Remove(file.Name);
+            }
+            else
+            {
+                var bytes = Encoding.UTF8.GetBytes(file.Content);
+                var blobId = repository.ObjectDatabase.Write<Blob>(bytes);
+                treeDefinition.Add(file.Name, blobId, Mode.NonExecutableFile);
+            }
         }
 
-        var signature = new Signature(authorName ?? Some.Name(), authorEmail ?? Some.Name(), DateTimeOffset.Now);
-        var committer = new Signature(committerName ?? Some.Name(), committerEmail ?? Some.Name(), DateTimeOffset.Now);
+        return CommitTreeDefinition(repository, parent, branchName, message, signature, treeDefinition);
+    }
 
-        repository.Commit(message ?? Some.Name(), signature, committer, new CommitOptions() { AllowEmptyCommit = allowEmptyCommit });
+    static LibGit2Sharp.Commit CommitTreeDefinition(Repository repository,
+        LibGit2Sharp.Commit? parent,
+        string? branchName,
+        string message,
+        Signature? signature,
+        TreeDefinition treeDefinition)
+    {
+        // Write the tree to the object database
+        var tree = repository.ObjectDatabase.CreateTree(treeDefinition);
 
-        if (branch is not null && pushToRemote)
+        // Create the commit
+        var parents = parent is null ? Array.Empty<LibGit2Sharp.Commit>() : new[] { parent };
+        var commit = repository.ObjectDatabase.CreateCommit(
+            signature,
+            signature,
+            message,
+            tree,
+            parents,
+            false);
+
+        if (branchName is not null)
         {
-            repository.Network.Push(branch);
+            // Point the branch at the new commit if a branch name
+            // has been provided
+            var branch = repository.Branches[branchName];
+
+            if (branch is null)
+            {
+                repository.Branches.Add(branchName, commit);
+            }
+            else
+            {
+                repository.Refs.UpdateTarget(branch.Reference, commit.Id);
+            }
         }
+
+        return commit;
     }
 }
 
@@ -216,7 +243,7 @@ public TestGitRepositoryBuilder WithNumberOfEmptyCommits(string branchName, int
         {
             commitBuilders.Add(b =>
             {
-                b.OnBranch(branchName).WithMessage($"Empty commit {i + 1}").AllowEmptyCommit();
+                b.OnBranch(branchName).WithMessage($"Empty commit {i + 1}");
 
                 if (pushToRemote)
                 {
@@ -234,7 +261,6 @@ public TestGitRepositoryBuilder WithNumberOfEmptyCommits(Action<CommitBuilder> c
             commitBuilders.Add(b =>
             {
                 commitBuilder(b);
-                b.AllowEmptyCommit();
             });
         }
         return this;
@@ -248,7 +274,6 @@ public TestGitRepositoryBuilder WithNumberOfEmptyCommitsOnRemoteTrackingBranchOf
             {
                 commitBuilder(b);
                 b.OnBranch(r => r.Branches[branch].TrackedBranch.CanonicalName);
-                b.AllowEmptyCommit();
             });
         }
         return this;