2 files changed, 80 insertions, 0 deletions
diff --git a/internal/testgit/object.go b/internal/testgit/object.go
new file mode 100644
index 00000000..0ea4d4d8
--- /dev/null
+++ b/internal/testgit/object.go
@@ -0,0 +1,27 @@
+package testgit
+
+import (
+	"io"
+	"testing"
+
+	"codeberg.org/lindenii/furgit/object/id"
+	"codeberg.org/lindenii/furgit/object/typ"
+)
+
+// HashObject hashes and writes an object and returns its object ID.
+func (repo *Repo) HashObject(tb testing.TB, ty typ.Type, body io.Reader) id.ObjectID {
+	tb.Helper()
+	cmd := repo.Command(tb, "git", "hash-object", "-t", ty.Name(), "-w", "--stdin", "--literally")
+
+	hex, err := cmd.CombinedOutput()
+	if err != nil {
+		tb.Fatalf("hash-object: %v", hex)
+	}
+
+	id, err := id.FromHex(repo.algo, string(hex))
+	if err != nil {
+		tb.Fatalf("parse git hash-object output %q: %v", hex, err)
+	}
+
+	return id
+}
diff --git a/internal/testgit/repo.go b/internal/testgit/repo.go
new file mode 100644
index 00000000..f18f199c
--- /dev/null
+++ b/internal/testgit/repo.go
@@ -0,0 +1,53 @@
+package testgit
+
+import (
+	"os"
+	"os/exec"
+	"testing"
+
+	"codeberg.org/lindenii/furgit/object/id"
+)
+
+type Repo struct {
+	path string
+	algo id.Algorithm
+	env  []string
+}
+
+func (repo *Repo) Command(
+	tb testing.TB,
+	command string,
+	args ...string,
+) *exec.Cmd {
+	//nolint:noctx
+	cmd := exec.Command(command, args...)
+	cmd.Dir = repo.path
+	cmd.Env = repo.env
+
+	return cmd
+}
+
+type RepoOptions struct {
+	ObjectFormat id.Algorithm
+}
+
+func NewRepo(tb testing.TB, opts RepoOptions) (*Repo, error) {
+	tb.Helper()
+
+	repo := &Repo{
+		path: tb.TempDir(),
+		algo: opts.ObjectFormat,
+		env: append(os.Environ(),
+			"GIT_CONFIG_GLOBAL=/dev/null",
+			"GIT_CONFIG_SYSTEM=/dev/null",
+			"GIT_AUTHOR_NAME=Test Author",
+			"GIT_AUTHOR_EMAIL=test@example.org",
+			"GIT_COMMITTER_NAME=Test Committer",
+			"GIT_COMMITTER_EMAIL=committer@example.org",
+			"GIT_AUTHOR_DATE=1234567890 +0000",
+			"GIT_COMMITTER_DATE=1234567890 +0000",
+		),
+	}
+
+	return repo, repo.Command(tb, "git", "init", "--object-format="+repo.algo.String(), "--", repo.path).Run()
+}