feat(tvix/store/protos): implement Size() and Digest() for Directory

This adds Size() and Digest() functions for the golang version.

Change-Id: If71445a9bb26100bb4076ac4f5c96945b33919f9
Reviewed-on: https://cl.tvl.fyi/c/depot/+/7325
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/store/protos/castore_test.go

@@ -0,0 +1,100 @@
+package storev1_test
+
+import (
+	"testing"
+
+	storev1pb "code.tvl.fyi/tvix/store/protos"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	dummyDigest = []byte{
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x00, 0x00, 0x00, 0x00,
+	}
+)
+
+func TestDirectorySize(t *testing.T) {
+	t.Run("empty", func(t *testing.T) {
+		d := storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{},
+			Files:       []*storev1pb.FileNode{},
+			Symlinks:    []*storev1pb.SymlinkNode{},
+		}
+
+		assert.Equal(t, uint32(0), d.Size())
+	})
+
+	t.Run("containing single empty directory", func(t *testing.T) {
+		d := storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{{
+				Name:   "foo",
+				Digest: dummyDigest,
+				Size:   0,
+			}},
+			Files:    []*storev1pb.FileNode{},
+			Symlinks: []*storev1pb.SymlinkNode{},
+		}
+
+		assert.Equal(t, uint32(1), d.Size())
+	})
+
+	t.Run("containing single non-empty directory", func(t *testing.T) {
+		d := storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{{
+				Name:   "foo",
+				Digest: dummyDigest,
+				Size:   4,
+			}},
+			Files:    []*storev1pb.FileNode{},
+			Symlinks: []*storev1pb.SymlinkNode{},
+		}
+
+		assert.Equal(t, uint32(5), d.Size())
+	})
+
+	t.Run("containing single file", func(t *testing.T) {
+		d := storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{},
+			Files: []*storev1pb.FileNode{{
+				Name:       "foo",
+				Digest:     dummyDigest,
+				Size:       42,
+				Executable: false,
+			}},
+			Symlinks: []*storev1pb.SymlinkNode{},
+		}
+
+		assert.Equal(t, uint32(1), d.Size())
+	})
+
+	t.Run("containing single symlink", func(t *testing.T) {
+		d := storev1pb.Directory{
+			Directories: []*storev1pb.DirectoryNode{},
+			Files:       []*storev1pb.FileNode{},
+			Symlinks: []*storev1pb.SymlinkNode{{
+				Name:   "foo",
+				Target: "bar",
+			}},
+		}
+
+		assert.Equal(t, uint32(1), d.Size())
+	})
+
+}
+func TestDirectoryDigest(t *testing.T) {
+	d := storev1pb.Directory{
+		Directories: []*storev1pb.DirectoryNode{},
+		Files:       []*storev1pb.FileNode{},
+		Symlinks:    []*storev1pb.SymlinkNode{},
+	}
+
+	dgst, err := d.Digest()
+	assert.NoError(t, err, "calling Digest() on a directory shouldn't error")
+	assert.Equal(t, []byte{
+		0xaf, 0x13, 0x49, 0xb9, 0xf5, 0xf9, 0xa1, 0xa6, 0xa0, 0x40, 0x4d, 0xea, 0x36, 0xdc,
+		0xc9, 0x49, 0x9b, 0xcb, 0x25, 0xc9, 0xad, 0xc1, 0x12, 0xb7, 0xcc, 0x9a, 0x93, 0xca,
+		0xe4, 0x1f, 0x32, 0x62,
+	}, dgst)
+}