feat(repo_blob): add CatFileBlob (#79)

Co-authored-by: Joe Chen <[email protected]>

repo_blob.go

@@ -0,0 +1,51 @@
+// Copyright 2022 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import "time"
+
+// CatFileBlobOptions contains optional arguments for verifying the objects.
+//
+// Docs: https://git-scm.com/docs/git-cat-file#Documentation/git-cat-file.txt
+type CatFileBlobOptions struct {
+	// The timeout duration before giving up for each shell command execution.
+	// The default timeout duration will be used when not supplied.
+	Timeout time.Duration
+	// The additional options to be passed to the underlying git.
+	CommandOptions
+}
+
+// CatFileBlob returns the blob corresponding to the given revision of the repository.
+func (r *Repository) CatFileBlob(rev string, opts ...CatFileBlobOptions) (*Blob, error) {
+	var opt CatFileBlobOptions
+	if len(opts) > 0 {
+		opt = opts[0]
+	}
+
+	rev, err := r.RevParse(rev, RevParseOptions{Timeout: opt.Timeout}) //nolint
+	if err != nil {
+		return nil, err
+	}
+
+	typ, err := r.CatFileType(rev)
+	if err != nil {
+		return nil, err
+	}
+
+	if typ != ObjectBlob {
+		return nil, ErrNotBlob
+	}
+
+	return &Blob{
+		TreeEntry: &TreeEntry{
+			mode: EntryBlob,
+			typ:  ObjectBlob,
+			id:   MustIDFromString(rev),
+			parent: &Tree{
+				repo: r,
+			},
+		},
+	}, nil
+}

repo_blob_test.go

@@ -0,0 +1,31 @@
+// Copyright 2022 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package git
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRepository_CatFileBlob(t *testing.T) {
+	t.Run("not a blob", func(t *testing.T) {
+		_, err := testrepo.CatFileBlob("007cb92318c7bd3b56908ea8c2e54370245562f8")
+		assert.Equal(t, ErrNotBlob, err)
+	})
+
+	t.Run("get a blob, no full rev hash", func(t *testing.T) {
+		b, err := testrepo.CatFileBlob("021a")
+		require.NoError(t, err)
+		assert.True(t, b.IsBlob())
+	})
+
+	t.Run("get a blob", func(t *testing.T) {
+		b, err := testrepo.CatFileBlob("021a721a61a1de65865542c405796d1eb985f784")
+		require.NoError(t, err)
+		assert.True(t, b.IsBlob())
+	})
+}