From 7c9b18f70bfe25b6681eb01c9208411dc475b90a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20T=C3=B6lle?= <julian.toelle97@gmail.com>
Date: Wed, 20 Nov 2024 22:03:22 +0100
Subject: [PATCH] test: add framework for go-git related testing

---
 internal/git/util_test.go | 169 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 169 insertions(+)
 create mode 100644 internal/git/util_test.go

diff --git a/internal/git/util_test.go b/internal/git/util_test.go
new file mode 100644
index 0000000..2ef4840
--- /dev/null
+++ b/internal/git/util_test.go
@@ -0,0 +1,169 @@
+package git
+
+import (
+	"io"
+	"log/slog"
+	"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)
+		}
+
+		// 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})
+	}
+}
+
+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)
+	}
+}
+
+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
+
+		repo.r, err = git.InitWithOptions(memory.NewStorage(), memfs.New(), git.InitOptions{
+			DefaultBranch: plumbing.Main,
+		})
+		require.NoError(t, err, "failed to create in-memory repository")
+
+		// Make initial commit
+		err = WithCommit("chore: init")(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
+	}
+}