test: add framework for go-git related testing

go.mod

@@ -6,6 +6,7 @@ toolchain go1.24.4
 
 require (
 	github.com/blang/semver/v4 v4.0.0
+	github.com/go-git/go-billy/v5 v5.6.2
 	github.com/go-git/go-git/v5 v5.16.2
 	github.com/google/go-github/v72 v72.0.0
 	github.com/leodido/go-conventionalcommits v0.12.0
@@ -25,7 +26,6 @@ require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
-	github.com/go-git/go-billy/v5 v5.6.2 // indirect
 	github.com/golang/groupcache v0.0.0-20241129210726-2c02b8208cf8 // indirect
 	github.com/google/go-querystring v1.1.0 // indirect
 	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect

internal/git/util_test.go

@@ -0,0 +1,189 @@
+package git
+
+import (
+	"fmt"
+	"io"
+	"log/slog"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/go-git/go-billy/v5/memfs"
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/plumbing"
+	"github.com/go-git/go-git/v5/plumbing/object"
+	"github.com/go-git/go-git/v5/storage/memory"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	author = &object.Signature{
+		Name: "releaser-pleaser",
+		When: time.Date(2020, 01, 01, 01, 01, 01, 01, time.UTC),
+	}
+)
+
+type CommitOption func(*commitOptions)
+type commitOptions struct {
+	cleanFiles bool
+	files      []commitFile
+	tags       []string
+	newRef     plumbing.ReferenceName
+	parentRef  plumbing.ReferenceName
+}
+type commitFile struct {
+	path    string
+	content string
+}
+
+type TestCommit func(*testing.T, *Repository) error
+type TestRepo func(*testing.T) *Repository
+
+func WithCommit(message string, options ...CommitOption) TestCommit {
+	return func(t *testing.T, repo *Repository) error {
+		t.Helper()
+
+		require.NotEmpty(t, message, "commit message is required")
+
+		opts := &commitOptions{}
+		for _, opt := range options {
+			opt(opts)
+		}
+
+		wt, err := repo.r.Worktree()
+		require.NoError(t, err)
+
+		if opts.parentRef != "" {
+			checkoutOptions := &git.CheckoutOptions{}
+
+			if opts.newRef != "" {
+				parentRef, err := repo.r.Reference(opts.parentRef, false)
+				require.NoError(t, err)
+
+				checkoutOptions.Create = true
+				checkoutOptions.Hash = parentRef.Hash()
+				checkoutOptions.Branch = opts.newRef
+			} else {
+				checkoutOptions.Branch = opts.parentRef
+			}
+
+			err = wt.Checkout(checkoutOptions)
+			require.NoError(t, err)
+		}
+
+		// Yeet all files
+		if opts.cleanFiles {
+			files, err := wt.Filesystem.ReadDir(".")
+			require.NoError(t, err, "failed to get current files")
+
+			for _, fileInfo := range files {
+				err = wt.Filesystem.Remove(fileInfo.Name())
+				require.NoError(t, err, "failed to remove file %q", fileInfo.Name())
+			}
+		}
+
+		// Create new files
+		for _, fileInfo := range opts.files {
+			file, err := wt.Filesystem.Create(fileInfo.path)
+			require.NoError(t, err, "failed to create file %q", fileInfo.path)
+
+			_, err = file.Write([]byte(fileInfo.content))
+			_ = file.Close()
+			require.NoError(t, err, "failed to write content to file %q", fileInfo.path)
+
+			_, err = wt.Add(fileInfo.path)
+			require.NoError(t, err, "failed to stage changes to file %q", fileInfo.path)
+
+		}
+
+		// Commit
+		commitHash, err := wt.Commit(message, &git.CommitOptions{
+			All:               true,
+			AllowEmptyCommits: true,
+			Author:            author,
+			Committer:         author,
+		})
+		require.NoError(t, err, "failed to commit")
+
+		// Create tags
+		for _, tagName := range opts.tags {
+			_, err = repo.r.CreateTag(tagName, commitHash, nil)
+			require.NoError(t, err, "failed to create tag %q", tagName)
+		}
+
+		return nil
+	}
+}
+
+func WithFile(path, content string) CommitOption {
+	return func(opts *commitOptions) {
+		opts.files = append(opts.files, commitFile{path: path, content: content})
+	}
+}
+
+// WithCleanFiles removes all previous files from the repo. Make sure to leave at least one file in the root
+// directory when switching branches!
+func WithCleanFiles() CommitOption {
+	return func(opts *commitOptions) {
+		opts.cleanFiles = true
+	}
+}
+
+func AsNewBranch(ref plumbing.ReferenceName) CommitOption {
+	return func(opts *commitOptions) {
+		opts.newRef = ref
+	}
+}
+
+func OnBranch(ref plumbing.ReferenceName) CommitOption {
+	return func(opts *commitOptions) {
+		opts.parentRef = ref
+	}
+}
+
+func WithTag(name string) CommitOption {
+	return func(opts *commitOptions) {
+		opts.tags = append(opts.tags, name)
+	}
+}
+
+// Can be useful to debug git issues by using it in a terminal
+const useOnDiskTestRepository = false
+
+func WithTestRepo(commits ...TestCommit) TestRepo {
+	return func(t *testing.T) *Repository {
+		t.Helper()
+
+		repo := &Repository{
+			logger: slog.New(slog.NewTextHandler(io.Discard, nil)),
+		}
+
+		var err error
+
+		initOptions := git.InitOptions{DefaultBranch: plumbing.Main}
+
+		if useOnDiskTestRepository {
+			dir, err := os.MkdirTemp(os.TempDir(), "rp-test-repo-")
+			require.NoError(t, err, "failed to create temp directory")
+
+			repo.r, err = git.PlainInitWithOptions(dir, &git.PlainInitOptions{InitOptions: initOptions})
+			require.NoError(t, err, "failed to create fs repository")
+
+			fmt.Printf("using temp directory: %s", dir)
+		} else {
+			repo.r, err = git.InitWithOptions(memory.NewStorage(), memfs.New(), initOptions)
+			require.NoError(t, err, "failed to create in-memory repository")
+		}
+
+		// Make initial commit
+		err = WithCommit("chore: init", WithFile("README.md", "# git test util"))(t, repo)
+		require.NoError(t, err, "failed to create init commit")
+
+		for i, commit := range commits {
+			err = commit(t, repo)
+			require.NoError(t, err, "failed to create commit %d", i)
+		}
+
+		return repo
+	}
+}