feat: add FetchBranch and CheckConflicts for merge queue
Add git helper functions for merge request conflict checking: - FetchBranch(remote, branch): fetch a specific branch from remote - CheckConflicts(source, target): test merge to detect conflicts - Returns list of conflicting files without modifying working directory - runMergeCheck helper to capture stdout (where CONFLICT appears) Tests cover clean merges, conflicting merges, and working dir cleanup. Closes gt-3x1.2 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Steve Yegge
@@ -91,6 +91,12 @@ func (g *Git) Fetch(remote string) error {
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return err
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}
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// FetchBranch fetches a specific branch from the remote.
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func (g *Git) FetchBranch(remote, branch string) error {
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_, err := g.run("fetch", remote, branch)
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return err
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}
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// Pull pulls from the remote branch.
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func (g *Git) Pull(remote, branch string) error {
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_, err := g.run("pull", remote, branch)
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@@ -207,6 +213,95 @@ func (g *Git) AbortMerge() error {
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return err
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}
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// CheckConflicts performs a test merge to check if source can be merged into target
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// without conflicts. Returns a list of conflicting files, or empty slice if clean.
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// The merge is always aborted after checking - no actual changes are made.
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//
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// The caller must ensure the working directory is clean before calling this.
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// After return, the working directory is restored to the target branch.
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func (g *Git) CheckConflicts(source, target string) ([]string, error) {
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// Checkout the target branch
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if err := g.Checkout(target); err != nil {
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return nil, fmt.Errorf("checkout target %s: %w", target, err)
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}
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// Attempt test merge with --no-commit --no-ff
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// We need to capture both stdout and stderr to detect conflicts
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_, mergeErr := g.runMergeCheck("merge", "--no-commit", "--no-ff", source)
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if mergeErr != nil {
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// Check if there are unmerged files (indicates conflict)
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conflicts, err := g.getConflictingFiles()
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if err == nil && len(conflicts) > 0 {
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// Abort the test merge
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g.AbortMerge()
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return conflicts, nil
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}
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// Check if it's a conflict error from wrapper
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if errors.Is(mergeErr, ErrMergeConflict) {
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g.AbortMerge()
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return conflicts, nil
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}
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// Some other merge error
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g.AbortMerge()
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return nil, mergeErr
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}
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// Merge succeeded (no conflicts) - abort the test merge
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// Use reset since --abort won't work on successful merge
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g.run("reset", "--hard", "HEAD")
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return nil, nil
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}
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// runMergeCheck runs a git merge command and returns error info from both stdout and stderr.
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// This is needed because git merge outputs CONFLICT info to stdout.
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func (g *Git) runMergeCheck(args ...string) (string, error) {
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cmd := exec.Command("git", args...)
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cmd.Dir = g.workDir
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var stdout, stderr bytes.Buffer
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cmd.Stdout = &stdout
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cmd.Stderr = &stderr
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err := cmd.Run()
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if err != nil {
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// Check stdout for CONFLICT message (git sends it there)
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stdoutStr := stdout.String()
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if strings.Contains(stdoutStr, "CONFLICT") {
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return "", ErrMergeConflict
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}
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// Fall back to stderr check
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return "", g.wrapError(err, stderr.String(), args)
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}
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return strings.TrimSpace(stdout.String()), nil
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}
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// getConflictingFiles returns the list of files with merge conflicts.
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func (g *Git) getConflictingFiles() ([]string, error) {
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// git diff --name-only --diff-filter=U shows unmerged files
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out, err := g.run("diff", "--name-only", "--diff-filter=U")
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if err != nil {
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return nil, err
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}
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if out == "" {
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return nil, nil
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}
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files := strings.Split(out, "\n")
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// Filter out empty strings
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var result []string
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for _, f := range files {
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if f != "" {
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result = append(result, f)
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}
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}
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return result, nil
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}
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// AbortRebase aborts a rebase in progress.
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func (g *Git) AbortRebase() error {
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_, err := g.run("rebase", "--abort")
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@@ -186,3 +186,157 @@ func TestRev(t *testing.T) {
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t.Errorf("hash length = %d, want 40", len(hash))
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}
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}
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func TestFetchBranch(t *testing.T) {
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// Create a "remote" repo
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remoteDir := t.TempDir()
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cmd := exec.Command("git", "init", "--bare")
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cmd.Dir = remoteDir
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if err := cmd.Run(); err != nil {
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t.Fatalf("git init --bare: %v", err)
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}
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// Create a local repo and push to remote
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localDir := initTestRepo(t)
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g := NewGit(localDir)
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// Add remote
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cmd = exec.Command("git", "remote", "add", "origin", remoteDir)
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cmd.Dir = localDir
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if err := cmd.Run(); err != nil {
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t.Fatalf("git remote add: %v", err)
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}
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// Push main branch
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mainBranch, _ := g.CurrentBranch()
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cmd = exec.Command("git", "push", "-u", "origin", mainBranch)
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cmd.Dir = localDir
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if err := cmd.Run(); err != nil {
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t.Fatalf("git push: %v", err)
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}
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// Fetch should succeed
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if err := g.FetchBranch("origin", mainBranch); err != nil {
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t.Errorf("FetchBranch: %v", err)
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}
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}
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func TestCheckConflicts_NoConflict(t *testing.T) {
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dir := initTestRepo(t)
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g := NewGit(dir)
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mainBranch, _ := g.CurrentBranch()
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// Create feature branch with non-conflicting change
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if err := g.CreateBranch("feature"); err != nil {
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t.Fatalf("CreateBranch: %v", err)
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}
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if err := g.Checkout("feature"); err != nil {
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t.Fatalf("Checkout feature: %v", err)
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}
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// Add a new file (won't conflict with main)
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newFile := filepath.Join(dir, "feature.txt")
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if err := os.WriteFile(newFile, []byte("feature content"), 0644); err != nil {
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t.Fatalf("write file: %v", err)
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}
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if err := g.Add("feature.txt"); err != nil {
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t.Fatalf("Add: %v", err)
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}
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if err := g.Commit("add feature file"); err != nil {
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t.Fatalf("Commit: %v", err)
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}
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// Go back to main
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if err := g.Checkout(mainBranch); err != nil {
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t.Fatalf("Checkout main: %v", err)
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}
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// Check for conflicts - should be none
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conflicts, err := g.CheckConflicts("feature", mainBranch)
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if err != nil {
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t.Fatalf("CheckConflicts: %v", err)
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}
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if len(conflicts) > 0 {
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t.Errorf("expected no conflicts, got %v", conflicts)
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}
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// Verify we're still on main and clean
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branch, _ := g.CurrentBranch()
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if branch != mainBranch {
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t.Errorf("branch = %q, want %q", branch, mainBranch)
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}
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status, _ := g.Status()
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if !status.Clean {
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t.Error("expected clean working directory after CheckConflicts")
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}
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}
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func TestCheckConflicts_WithConflict(t *testing.T) {
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dir := initTestRepo(t)
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g := NewGit(dir)
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mainBranch, _ := g.CurrentBranch()
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// Create feature branch
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if err := g.CreateBranch("feature"); err != nil {
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t.Fatalf("CreateBranch: %v", err)
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}
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if err := g.Checkout("feature"); err != nil {
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t.Fatalf("Checkout feature: %v", err)
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}
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// Modify README.md on feature branch
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readmeFile := filepath.Join(dir, "README.md")
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if err := os.WriteFile(readmeFile, []byte("# Feature changes\n"), 0644); err != nil {
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t.Fatalf("write file: %v", err)
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}
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if err := g.Add("README.md"); err != nil {
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t.Fatalf("Add: %v", err)
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}
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if err := g.Commit("modify readme on feature"); err != nil {
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t.Fatalf("Commit: %v", err)
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}
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// Go back to main and make conflicting change
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if err := g.Checkout(mainBranch); err != nil {
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t.Fatalf("Checkout main: %v", err)
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}
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if err := os.WriteFile(readmeFile, []byte("# Main changes\n"), 0644); err != nil {
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t.Fatalf("write file: %v", err)
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}
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if err := g.Add("README.md"); err != nil {
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t.Fatalf("Add: %v", err)
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}
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if err := g.Commit("modify readme on main"); err != nil {
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t.Fatalf("Commit: %v", err)
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}
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// Check for conflicts - should find README.md
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conflicts, err := g.CheckConflicts("feature", mainBranch)
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if err != nil {
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t.Fatalf("CheckConflicts: %v", err)
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}
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if len(conflicts) == 0 {
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t.Error("expected conflicts, got none")
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}
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foundReadme := false
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for _, f := range conflicts {
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if f == "README.md" {
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foundReadme = true
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break
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}
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}
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if !foundReadme {
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t.Errorf("expected README.md in conflicts, got %v", conflicts)
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}
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// Verify we're still on main and clean
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branch, _ := g.CurrentBranch()
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if branch != mainBranch {
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t.Errorf("branch = %q, want %q", branch, mainBranch)
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}
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status, _ := g.Status()
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if !status.Clean {
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t.Error("expected clean working directory after CheckConflicts")
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}
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}
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