internal/testgit: Add helpers to prepare for commit testing

1 files changed, 34 insertions, 0 deletions

diff --git a/internal/testgit/commit.go b/internal/testgit/commit.go
new file mode 100644
index 00000000..09a5438d
--- /dev/null
+++ b/internal/testgit/commit.go
@@ -0,0 +1,34 @@
+package testgit
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"lindenii.org/go/furgit/object/id"
+)
+
+// CommitTree creates a commit object from a tree and optional parents,
+// and returns its object ID.
+func (repo *Repo) CommitTree(tb testing.TB, tree id.ObjectID, message string, parents ...id.ObjectID) (id.ObjectID, error) {
+	tb.Helper()
+
+	args := []string{"commit-tree", tree.String()}
+	for _, parent := range parents {
+		args = append(args, "-p", parent.String())
+	}
+
+	args = append(args, "-m", message)
+
+	stdout, err := repo.Run(tb, nil, "git", args...)
+	if err != nil {
+		return id.ObjectID{}, fmt.Errorf("commit-tree: %w", err)
+	}
+
+	commitID, err := repo.objectFormat.FromString(strings.TrimSuffix(string(stdout), "\n"))
+	if err != nil {
+		return id.ObjectID{}, fmt.Errorf("parse git commit-tree output %q: %w", string(stdout), err)
+	}
+
+	return commitID, nil
+}