refactor(tvix/nar-bridge): drop reader package r/6693

Make the import function usable on any reader.

Change-Id: I84d2004cb73cdd7a11fe8efb0f2efb6335d5e6b0
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9527
Reviewed-by: Connor Brewster <cbrewster@hey.com>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>

1 files changed, 591 insertions, 0 deletions

diff --git a/tvix/nar-bridge/pkg/importer/importer_test.go b/tvix/nar-bridge/pkg/importer/importer_test.go
new file mode 100644
index 000000000000..0557c1d6dd1f
--- /dev/null
+++ b/tvix/nar-bridge/pkg/importer/importer_test.go
@@ -0,0 +1,591 @@
+package importer_test
+
+import (
+	"context"
+	"errors"
+	"io"
+	"os"
+	"testing"
+
+	castorev1pb "code.tvl.fyi/tvix/castore/protos"
+	"code.tvl.fyi/tvix/nar-bridge/pkg/importer"
+	storev1pb "code.tvl.fyi/tvix/store/protos"
+	"github.com/google/go-cmp/cmp"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/protobuf/testing/protocmp"
+)
+
+func requireProtoEq(t *testing.T, expected interface{}, actual interface{}) {
+	if diff := cmp.Diff(expected, actual, protocmp.Transform()); diff != "" {
+		t.Errorf("unexpected difference:\n%v", diff)
+	}
+}
+
+func mustDigest(d *castorev1pb.Directory) []byte {
+	dgst, err := d.Digest()
+	if err != nil {
+		panic(err)
+	}
+	return dgst
+}
+
+func TestSymlink(t *testing.T) {
+	f, err := os.Open("../../testdata/symlink.nar")
+	require.NoError(t, err)
+
+	actualPathInfo, err := importer.Import(
+		context.Background(),
+		f,
+		func(fileReader io.Reader) error {
+			panic("no file contents expected!")
+		}, func(directory *castorev1pb.Directory) error {
+			panic("no directories expected!")
+		},
+	)
+	require.NoError(t, err)
+
+	expectedPathInfo := &storev1pb.PathInfo{
+		Node: &castorev1pb.Node{
+			Node: &castorev1pb.Node_Symlink{
+				Symlink: &castorev1pb.SymlinkNode{
+					Name:   []byte(""),
+					Target: []byte("/nix/store/somewhereelse"),
+				},
+			},
+		},
+		References: [][]byte{},
+		Narinfo: &storev1pb.NARInfo{
+			NarSize: 136,
+			NarSha256: []byte{
+				0x09, 0x7d, 0x39, 0x7e, 0x9b, 0x58, 0x26, 0x38, 0x4e, 0xaa, 0x16, 0xc4, 0x57, 0x71, 0x5d, 0x1c, 0x1a, 0x51, 0x67, 0x03, 0x13, 0xea, 0xd0, 0xf5, 0x85, 0x66, 0xe0, 0xb2, 0x32, 0x53, 0x9c, 0xf1,
+			},
+			Signatures:     []*storev1pb.NARInfo_Signature{},
+			ReferenceNames: []string{},
+		},
+	}
+
+	requireProtoEq(t, expectedPathInfo, actualPathInfo)
+}
+
+func TestRegular(t *testing.T) {
+	f, err := os.Open("../../testdata/onebyteregular.nar")
+	require.NoError(t, err)
+
+	actualPathInfo, err := importer.Import(
+		context.Background(),
+		f,
+		func(fileReader io.Reader) error {
+			contents, err := io.ReadAll(fileReader)
+			require.NoError(t, err, "reading fileReader should not error")
+			require.Equal(t, []byte{0x01}, contents, "contents read from fileReader should match expectations")
+			return nil
+		}, func(directory *castorev1pb.Directory) error {
+			panic("no directories expected!")
+		},
+	)
+	require.NoError(t, err)
+
+	// The blake3 digest of the 0x01 byte.
+	BLAKE3_DIGEST_0X01 := []byte{
+		0x48, 0xfc, 0x72, 0x1f, 0xbb, 0xc1, 0x72, 0xe0, 0x92, 0x5f, 0xa2, 0x7a, 0xf1, 0x67, 0x1d,
+		0xe2, 0x25, 0xba, 0x92, 0x71, 0x34, 0x80, 0x29, 0x98, 0xb1, 0x0a, 0x15, 0x68, 0xa1, 0x88,
+		0x65, 0x2b,
+	}
+
+	expectedPathInfo := &storev1pb.PathInfo{
+		Node: &castorev1pb.Node{
+			Node: &castorev1pb.Node_File{
+				File: &castorev1pb.FileNode{
+					Name:       []byte(""),
+					Digest:     BLAKE3_DIGEST_0X01,
+					Size:       1,
+					Executable: false,
+				},
+			},
+		},
+		References: [][]byte{},
+		Narinfo: &storev1pb.NARInfo{
+			NarSize: 120,
+			NarSha256: []byte{
+				0x73, 0x08, 0x50, 0xa8, 0x11, 0x25, 0x9d, 0xbf, 0x3a, 0x68, 0xdc, 0x2e, 0xe8, 0x7a, 0x79, 0xaa, 0x6c, 0xae, 0x9f, 0x71, 0x37, 0x5e, 0xdf, 0x39, 0x6f, 0x9d, 0x7a, 0x91, 0xfb, 0xe9, 0x13, 0x4d,
+			},
+			Signatures:     []*storev1pb.NARInfo_Signature{},
+			ReferenceNames: []string{},
+		},
+	}
+
+	requireProtoEq(t, expectedPathInfo, actualPathInfo)
+}
+
+func TestEmptyDirectory(t *testing.T) {
+	f, err := os.Open("../../testdata/emptydirectory.nar")
+	require.NoError(t, err)
+
+	expectedDirectory := &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{},
+		Files:       []*castorev1pb.FileNode{},
+		Symlinks:    []*castorev1pb.SymlinkNode{},
+	}
+	actualPathInfo, err := importer.Import(
+		context.Background(),
+		f,
+		func(fileReader io.Reader) error {
+			panic("no file contents expected!")
+		}, func(directory *castorev1pb.Directory) error {
+			requireProtoEq(t, expectedDirectory, directory)
+			return nil
+		},
+	)
+	require.NoError(t, err)
+
+	expectedPathInfo := &storev1pb.PathInfo{
+		Node: &castorev1pb.Node{
+			Node: &castorev1pb.Node_Directory{
+				Directory: &castorev1pb.DirectoryNode{
+					Name:   []byte(""),
+					Digest: mustDigest(expectedDirectory),
+					Size:   expectedDirectory.Size(),
+				},
+			},
+		},
+		References: [][]byte{},
+		Narinfo: &storev1pb.NARInfo{
+			NarSize: 96,
+			NarSha256: []byte{
+				0xa5, 0x0a, 0x5a, 0xb6, 0xd9, 0x92, 0xf5, 0x59, 0x8e, 0xdd, 0x92, 0x10, 0x50, 0x59, 0xfa, 0xe9, 0xac, 0xfc, 0x19, 0x29, 0x81, 0xe0, 0x8b, 0xd8, 0x85, 0x34, 0xc2, 0x16, 0x7e, 0x92, 0x52, 0x6a,
+			},
+			Signatures:     []*storev1pb.NARInfo_Signature{},
+			ReferenceNames: []string{},
+		},
+	}
+	requireProtoEq(t, expectedPathInfo, actualPathInfo)
+}
+
+func TestFull(t *testing.T) {
+	f, err := os.Open("../../testdata/nar_1094wph9z4nwlgvsd53abfz8i117ykiv5dwnq9nnhz846s7xqd7d.nar")
+	require.NoError(t, err)
+
+	expectedDirectoryPaths := []string{
+		"/bin",
+		"/share/man/man1",
+		"/share/man/man5",
+		"/share/man/man8",
+		"/share/man",
+		"/share",
+		"/",
+	}
+	expectedDirectories := make(map[string]*castorev1pb.Directory, len(expectedDirectoryPaths))
+
+	// /bin is a leaf directory
+	expectedDirectories["/bin"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{},
+		Files: []*castorev1pb.FileNode{
+			{
+				Name: []byte("arp"),
+				Digest: []byte{
+					0xfb, 0xc4, 0x61, 0x4a, 0x29, 0x27, 0x11, 0xcb, 0xcc, 0xe4, 0x99, 0x81, 0x9c, 0xf0, 0xa9, 0x17, 0xf7, 0xd0, 0x91, 0xbe, 0xea, 0x08, 0xcb, 0x5b, 0xaa, 0x76, 0x76, 0xf5, 0xee, 0x4f, 0x82, 0xbb,
+				},
+				Size:       55288,
+				Executable: true,
+			},
+			{
+				Name: []byte("hostname"),
+				Digest: []byte{
+					0x9c, 0x6a, 0xe4, 0xb5, 0xe4, 0x6c, 0xb5, 0x67, 0x45, 0x0e, 0xaa, 0x2a, 0xd8, 0xdd, 0x9b, 0x38, 0xd7, 0xed, 0x01, 0x02, 0x84, 0xf7, 0x26, 0xe1, 0xc7, 0xf3, 0x1c, 0xeb, 0xaa, 0x8a, 0x01, 0x30,
+				},
+				Size:       17704,
+				Executable: true,
+			},
+			{
+				Name: []byte("ifconfig"),
+				Digest: []byte{
+					0x25, 0xbe, 0x3b, 0x1d, 0xf4, 0x1a, 0x45, 0x42, 0x79, 0x09, 0x2c, 0x2a, 0x83, 0xf0, 0x0b, 0xff, 0xe8, 0xc0, 0x9c, 0x26, 0x98, 0x70, 0x15, 0x4d, 0xa8, 0xca, 0x05, 0xfe, 0x92, 0x68, 0x35, 0x2e,
+				},
+				Size:       72576,
+				Executable: true,
+			},
+			{
+				Name: []byte("nameif"),
+				Digest: []byte{
+					0x8e, 0xaa, 0xc5, 0xdb, 0x71, 0x08, 0x8e, 0xe5, 0xe6, 0x30, 0x1f, 0x2c, 0x3a, 0xf2, 0x42, 0x39, 0x0c, 0x57, 0x15, 0xaf, 0x50, 0xaa, 0x1c, 0xdf, 0x84, 0x22, 0x08, 0x77, 0x03, 0x54, 0x62, 0xb1,
+				},
+				Size:       18776,
+				Executable: true,
+			},
+			{
+				Name: []byte("netstat"),
+				Digest: []byte{
+					0x13, 0x34, 0x7e, 0xdd, 0x2a, 0x9a, 0x17, 0x0b, 0x3f, 0xc7, 0x0a, 0xe4, 0x92, 0x89, 0x25, 0x9f, 0xaa, 0xb5, 0x05, 0x6b, 0x24, 0xa7, 0x91, 0xeb, 0xaf, 0xf9, 0xe9, 0x35, 0x56, 0xaa, 0x2f, 0xb2,
+				},
+				Size:       131784,
+				Executable: true,
+			},
+			{
+				Name: []byte("plipconfig"),
+				Digest: []byte{
+					0x19, 0x7c, 0x80, 0xdc, 0x81, 0xdc, 0xb4, 0xc0, 0x45, 0xe1, 0xf9, 0x76, 0x51, 0x4f, 0x50, 0xbf, 0xa4, 0x69, 0x51, 0x9a, 0xd4, 0xa9, 0xe7, 0xaa, 0xe7, 0x0d, 0x53, 0x32, 0xff, 0x28, 0x40, 0x60,
+				},
+				Size:       13160,
+				Executable: true,
+			},
+			{
+				Name: []byte("rarp"),
+				Digest: []byte{
+					0x08, 0x85, 0xb4, 0x85, 0x03, 0x2b, 0x3c, 0x7a, 0x3e, 0x24, 0x4c, 0xf8, 0xcc, 0x45, 0x01, 0x9e, 0x79, 0x43, 0x8c, 0x6f, 0x5e, 0x32, 0x46, 0x54, 0xb6, 0x68, 0x91, 0x8e, 0xa0, 0xcb, 0x6e, 0x0d,
+				},
+				Size:       30384,
+				Executable: true,
+			},
+			{
+				Name: []byte("route"),
+				Digest: []byte{
+					0x4d, 0x14, 0x20, 0x89, 0x9e, 0x76, 0xf4, 0xe2, 0x92, 0x53, 0xee, 0x9b, 0x78, 0x7d, 0x23, 0x80, 0x6c, 0xff, 0xe6, 0x33, 0xdc, 0x4a, 0x10, 0x29, 0x39, 0x02, 0xa0, 0x60, 0xff, 0xe2, 0xbb, 0xd7,
+				},
+				Size:       61928,
+				Executable: true,
+			},
+			{
+				Name: []byte("slattach"),
+				Digest: []byte{
+					0xfb, 0x25, 0xc3, 0x73, 0xb7, 0xb1, 0x0b, 0x25, 0xcd, 0x7b, 0x62, 0xf6, 0x71, 0x83, 0xfe, 0x36, 0x80, 0xf6, 0x48, 0xc3, 0xdb, 0xd8, 0x0c, 0xfe, 0xb8, 0xd3, 0xda, 0x32, 0x9b, 0x47, 0x4b, 0x05,
+				},
+				Size:       35672,
+				Executable: true,
+			},
+		},
+		Symlinks: []*castorev1pb.SymlinkNode{
+			{
+				Name:   []byte("dnsdomainname"),
+				Target: []byte("hostname"),
+			},
+			{
+				Name:   []byte("domainname"),
+				Target: []byte("hostname"),
+			},
+			{
+				Name:   []byte("nisdomainname"),
+				Target: []byte("hostname"),
+			},
+			{
+				Name:   []byte("ypdomainname"),
+				Target: []byte("hostname"),
+			},
+		},
+	}
+
+	// /share/man/man1 is a leaf directory.
+	// The parser traversed over /sbin, but only added it to / which is still on the stack.
+	expectedDirectories["/share/man/man1"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{},
+		Files: []*castorev1pb.FileNode{
+			{
+				Name: []byte("dnsdomainname.1.gz"),
+				Digest: []byte{
+					0x98, 0x8a, 0xbd, 0xfa, 0x64, 0xd5, 0xb9, 0x27, 0xfe, 0x37, 0x43, 0x56, 0xb3, 0x18, 0xc7, 0x2b, 0xcb, 0xe3, 0x17, 0x1c, 0x17, 0xf4, 0x17, 0xeb, 0x4a, 0xa4, 0x99, 0x64, 0x39, 0xca, 0x2d, 0xee,
+				},
+				Size:       40,
+				Executable: false,
+			},
+			{
+				Name: []byte("domainname.1.gz"),
+				Digest: []byte{
+					0x98, 0x8a, 0xbd, 0xfa, 0x64, 0xd5, 0xb9, 0x27, 0xfe, 0x37, 0x43, 0x56, 0xb3, 0x18, 0xc7, 0x2b, 0xcb, 0xe3, 0x17, 0x1c, 0x17, 0xf4, 0x17, 0xeb, 0x4a, 0xa4, 0x99, 0x64, 0x39, 0xca, 0x2d, 0xee,
+				},
+				Size:       40,
+				Executable: false,
+			},
+			{
+				Name: []byte("hostname.1.gz"),
+				Digest: []byte{
+					0xbf, 0x89, 0xe6, 0x28, 0x00, 0x24, 0x66, 0x79, 0x70, 0x04, 0x38, 0xd6, 0xdd, 0x9d, 0xf6, 0x0e, 0x0d, 0xee, 0x00, 0xf7, 0x64, 0x4f, 0x05, 0x08, 0x9d, 0xf0, 0x36, 0xde, 0x85, 0xf4, 0x75, 0xdb,
+				},
+				Size:       1660,
+				Executable: false,
+			},
+			{
+				Name: []byte("nisdomainname.1.gz"),
+				Digest: []byte{
+					0x98, 0x8a, 0xbd, 0xfa, 0x64, 0xd5, 0xb9, 0x27, 0xfe, 0x37, 0x43, 0x56, 0xb3, 0x18, 0xc7, 0x2b, 0xcb, 0xe3, 0x17, 0x1c, 0x17, 0xf4, 0x17, 0xeb, 0x4a, 0xa4, 0x99, 0x64, 0x39, 0xca, 0x2d, 0xee,
+				},
+				Size:       40,
+				Executable: false,
+			},
+			{
+				Name: []byte("ypdomainname.1.gz"),
+				Digest: []byte{
+					0x98, 0x8a, 0xbd, 0xfa, 0x64, 0xd5, 0xb9, 0x27, 0xfe, 0x37, 0x43, 0x56, 0xb3, 0x18, 0xc7, 0x2b, 0xcb, 0xe3, 0x17, 0x1c, 0x17, 0xf4, 0x17, 0xeb, 0x4a, 0xa4, 0x99, 0x64, 0x39, 0xca, 0x2d, 0xee,
+				},
+				Size:       40,
+				Executable: false,
+			},
+		},
+		Symlinks: []*castorev1pb.SymlinkNode{},
+	}
+
+	// /share/man/man5 is a leaf directory
+	expectedDirectories["/share/man/man5"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{},
+		Files: []*castorev1pb.FileNode{
+			{
+				Name: []byte("ethers.5.gz"),
+				Digest: []byte{
+					0x42, 0x63, 0x8c, 0xc4, 0x18, 0x93, 0xcf, 0x60, 0xd6, 0xff, 0x43, 0xbc, 0x16, 0xb4, 0xfd, 0x22, 0xd2, 0xf2, 0x05, 0x0b, 0x52, 0xdc, 0x6a, 0x6b, 0xff, 0x34, 0xe2, 0x6a, 0x38, 0x3a, 0x07, 0xe3,
+				},
+				Size:       563,
+				Executable: false,
+			},
+		},
+		Symlinks: []*castorev1pb.SymlinkNode{},
+	}
+
+	// /share/man/man8 is a leaf directory
+	expectedDirectories["/share/man/man8"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{},
+		Files: []*castorev1pb.FileNode{
+			{
+				Name: []byte("arp.8.gz"),
+				Digest: []byte{
+					0xf5, 0x35, 0x4e, 0xf5, 0xf6, 0x44, 0xf7, 0x52, 0x0f, 0x42, 0xa0, 0x26, 0x51, 0xd9, 0x89, 0xf9, 0x68, 0xf2, 0xef, 0xeb, 0xba, 0xe1, 0xf4, 0x55, 0x01, 0x57, 0x77, 0xb7, 0x68, 0x55, 0x92, 0xef,
+				},
+				Size:       2464,
+				Executable: false,
+			},
+			{
+				Name: []byte("ifconfig.8.gz"),
+				Digest: []byte{
+					0x18, 0x65, 0x25, 0x11, 0x32, 0xee, 0x77, 0x91, 0x35, 0x4c, 0x3c, 0x24, 0xdb, 0xaf, 0x66, 0xdb, 0xfc, 0x17, 0x7b, 0xba, 0xe1, 0x3d, 0x05, 0xd2, 0xca, 0x6e, 0x2c, 0xe4, 0xef, 0xb8, 0xa8, 0xbe,
+				},
+				Size:       3382,
+				Executable: false,
+			},
+			{
+				Name: []byte("nameif.8.gz"),
+				Digest: []byte{
+					0x73, 0xc1, 0x27, 0xe8, 0x3b, 0xa8, 0x49, 0xdc, 0x0e, 0xdf, 0x70, 0x5f, 0xaf, 0x06, 0x01, 0x2c, 0x62, 0xe9, 0x18, 0x67, 0x01, 0x94, 0x64, 0x26, 0xca, 0x95, 0x22, 0xc0, 0xdc, 0xe4, 0x42, 0xb6,
+				},
+				Size:       523,
+				Executable: false,
+			},
+			{
+				Name: []byte("netstat.8.gz"),
+				Digest: []byte{
+					0xc0, 0x86, 0x43, 0x4a, 0x43, 0x57, 0xaa, 0x84, 0xa7, 0x24, 0xa0, 0x7c, 0x65, 0x38, 0x46, 0x1c, 0xf2, 0x45, 0xa2, 0xef, 0x12, 0x44, 0x18, 0xba, 0x52, 0x56, 0xe9, 0x8e, 0x6a, 0x0f, 0x70, 0x63,
+				},
+				Size:       4284,
+				Executable: false,
+			},
+			{
+				Name: []byte("plipconfig.8.gz"),
+				Digest: []byte{
+					0x2a, 0xd9, 0x1d, 0xa8, 0x9e, 0x0d, 0x05, 0xd0, 0xb0, 0x49, 0xaa, 0x64, 0xba, 0x29, 0x28, 0xc6, 0x45, 0xe1, 0xbb, 0x5e, 0x72, 0x8d, 0x48, 0x7b, 0x09, 0x4f, 0x0a, 0x82, 0x1e, 0x26, 0x83, 0xab,
+				},
+				Size:       889,
+				Executable: false,
+			},
+			{
+				Name: []byte("rarp.8.gz"),
+				Digest: []byte{
+					0x3d, 0x51, 0xc1, 0xd0, 0x6a, 0x59, 0x1e, 0x6d, 0x9a, 0xf5, 0x06, 0xd2, 0xe7, 0x7d, 0x7d, 0xd0, 0x70, 0x3d, 0x84, 0x64, 0xc3, 0x7d, 0xfb, 0x10, 0x84, 0x3b, 0xe1, 0xa9, 0xdf, 0x46, 0xee, 0x9f,
+				},
+				Size:       1198,
+				Executable: false,
+			},
+			{
+				Name: []byte("route.8.gz"),
+				Digest: []byte{
+					0x2a, 0x5a, 0x4b, 0x4f, 0x91, 0xf2, 0x78, 0xe4, 0xa9, 0x25, 0xb2, 0x7f, 0xa7, 0x2a, 0xc0, 0x8a, 0x4a, 0x65, 0xc9, 0x5f, 0x07, 0xa0, 0x48, 0x44, 0xeb, 0x46, 0xf9, 0xc9, 0xe1, 0x17, 0x96, 0x21,
+				},
+				Size:       3525,
+				Executable: false,
+			},
+			{
+				Name: []byte("slattach.8.gz"),
+				Digest: []byte{
+					0x3f, 0x05, 0x6b, 0x20, 0xe1, 0xe4, 0xf0, 0xba, 0x16, 0x15, 0x66, 0x6b, 0x57, 0x96, 0xe9, 0x9d, 0x83, 0xa8, 0x20, 0xaf, 0x8a, 0xca, 0x16, 0x4d, 0xa2, 0x6d, 0x94, 0x8e, 0xca, 0x91, 0x8f, 0xd4,
+				},
+				Size:       1441,
+				Executable: false,
+			},
+		},
+		Symlinks: []*castorev1pb.SymlinkNode{},
+	}
+
+	// /share/man holds /share/man/man{1,5,8}.
+	expectedDirectories["/share/man"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{
+			{
+				Name:   []byte("man1"),
+				Digest: mustDigest(expectedDirectories["/share/man/man1"]),
+				Size:   expectedDirectories["/share/man/man1"].Size(),
+			},
+			{
+				Name:   []byte("man5"),
+				Digest: mustDigest(expectedDirectories["/share/man/man5"]),
+				Size:   expectedDirectories["/share/man/man5"].Size(),
+			},
+			{
+				Name:   []byte("man8"),
+				Digest: mustDigest(expectedDirectories["/share/man/man8"]),
+				Size:   expectedDirectories["/share/man/man8"].Size(),
+			},
+		},
+		Files:    []*castorev1pb.FileNode{},
+		Symlinks: []*castorev1pb.SymlinkNode{},
+	}
+
+	// /share holds /share/man.
+	expectedDirectories["/share"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{
+			{
+				Name:   []byte("man"),
+				Digest: mustDigest(expectedDirectories["/share/man"]),
+				Size:   expectedDirectories["/share/man"].Size(),
+			},
+		},
+		Files:    []*castorev1pb.FileNode{},
+		Symlinks: []*castorev1pb.SymlinkNode{},
+	}
+
+	// / holds /bin, /share, and a /sbin symlink.
+	expectedDirectories["/"] = &castorev1pb.Directory{
+		Directories: []*castorev1pb.DirectoryNode{
+			{
+				Name:   []byte("bin"),
+				Digest: mustDigest(expectedDirectories["/bin"]),
+				Size:   expectedDirectories["/bin"].Size(),
+			},
+			{
+				Name:   []byte("share"),
+				Digest: mustDigest(expectedDirectories["/share"]),
+				Size:   expectedDirectories["/share"].Size(),
+			},
+		},
+		Files: []*castorev1pb.FileNode{},
+		Symlinks: []*castorev1pb.SymlinkNode{
+			{
+				Name:   []byte("sbin"),
+				Target: []byte("bin"),
+			},
+		},
+	}
+	// assert we populated the two fixtures properly
+	require.Equal(t, len(expectedDirectoryPaths), len(expectedDirectories))
+
+	numDirectoriesReceived := 0
+
+	actualPathInfo, err := importer.Import(
+		context.Background(),
+		f,
+		func(fileReader io.Reader) error {
+			// Don't really bother reading and comparing the contents here,
+			// We already verify the right digests are produced by comparing the
+			// directoryCb calls, and TestRegular ensures the reader works.
+			// This also covers the case when the client doesn't read from the reader, and that the
+			// importer will take care of reading all the way to the end no matter what.
+			return nil
+		}, func(directory *castorev1pb.Directory) error {
+			// use actualDirectoryOrder to look up the Directory object we expect at this specific invocation.
+			currentDirectoryPath := expectedDirectoryPaths[numDirectoriesReceived]
+
+			expectedDirectory, found := expectedDirectories[currentDirectoryPath]
+			require.True(t, found, "must find the current directory")
+
+			requireProtoEq(t, expectedDirectory, directory)
+
+			numDirectoriesReceived += 1
+			return nil
+		},
+	)
+	require.NoError(t, err)
+
+	expectedPathInfo := &storev1pb.PathInfo{
+		Node: &castorev1pb.Node{
+			Node: &castorev1pb.Node_Directory{
+				Directory: &castorev1pb.DirectoryNode{
+					Name:   []byte(""),
+					Digest: mustDigest(expectedDirectories["/"]),
+					Size:   expectedDirectories["/"].Size(),
+				},
+			},
+		},
+		References: [][]byte{},
+		Narinfo: &storev1pb.NARInfo{
+			NarSize: 464152,
+			NarSha256: []byte{
+				0xc6, 0xe1, 0x55, 0xb3, 0x45, 0x6e, 0x30, 0xb7, 0x61, 0x22, 0x63, 0xec, 0x09, 0x50, 0x70, 0x81, 0x1c, 0xaf, 0x8a, 0xbf, 0xd5, 0x9f, 0xaa, 0x72, 0xab, 0x82, 0xa5, 0x92, 0xef, 0xde, 0xb2, 0x53,
+			},
+			Signatures:     []*storev1pb.NARInfo_Signature{},
+			ReferenceNames: []string{},
+		},
+	}
+	requireProtoEq(t, expectedPathInfo, actualPathInfo)
+}
+
+// TestCallbackErrors ensures that errors returned from the callback function
+// bubble up to the importer process, and are not ignored.
+func TestCallbackErrors(t *testing.T) {
+	t.Run("callback file", func(t *testing.T) {
+		// Pick an example NAR with a regular file.
+		f, err := os.Open("../../testdata/onebyteregular.nar")
+		require.NoError(t, err)
+
+		targetErr := errors.New("expected error")
+
+		_, err = importer.Import(
+			context.Background(),
+			f,
+			func(fileReader io.Reader) error {
+				return targetErr
+			}, func(directory *castorev1pb.Directory) error {
+				panic("no directories expected!")
+			},
+		)
+		require.ErrorIs(t, err, targetErr)
+	})
+	t.Run("callback directory", func(t *testing.T) {
+		// Pick an example NAR with a directory node
+		f, err := os.Open("../../testdata/emptydirectory.nar")
+		require.NoError(t, err)
+
+		targetErr := errors.New("expected error")
+
+		_, err = importer.Import(
+			context.Background(),
+			f,
+			func(fileReader io.Reader) error {
+				panic("no file contents expected!")
+			}, func(directory *castorev1pb.Directory) error {
+				return targetErr
+			},
+		)
+		require.ErrorIs(t, err, targetErr)
+	})
+}
+
+// TestPopDirectories is a regression test that ensures we handle the directory
+// stack properly.
+//
+// This test case looks like:
+//
+// / (dir)
+// /test (dir)
+// /test/tested (file)
+// /tested (file)
+//
+// We used to have a bug where the second `tested` file would appear as if
+// it was in the `/test` dir because it has that dir as a string prefix.
+func TestPopDirectories(t *testing.T) {
+	f, err := os.Open("../../testdata/popdirectories.nar")
+	require.NoError(t, err)
+	defer f.Close()
+
+	_, err = importer.Import(
+		context.Background(),
+		f,
+		func(fileReader io.Reader) error { return nil },
+		func(directory *castorev1pb.Directory) error {
+			return directory.Validate()
+		},
+	)
+	require.NoError(t, err)
+}