Make filer.Filer return fs.DirEntry from ReadDir (#415)

## Changes

This allows for compatibility with the stdlib functions in io/fs.

## Tests

Integration tests pass.

internal/filer_test.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net/http"
 	"strings"
 	"testing"
@@ -75,6 +76,7 @@ func runFilerReadWriteTest(t *testing.T, ctx context.Context, f filer.Filer) {
 
 func runFilerReadDirTest(t *testing.T, ctx context.Context, f filer.Filer) {
 	var err error
+	var info fs.FileInfo
 
 	// We start with an empty directory.
 	entries, err := f.ReadDir(ctx, ".")
@@ -105,23 +107,32 @@ func runFilerReadDirTest(t *testing.T, ctx context.Context, f filer.Filer) {
 	entries, err = f.ReadDir(ctx, ".")
 	require.NoError(t, err)
 	assert.Len(t, entries, 2)
-	assert.Equal(t, "dir", entries[0].Name)
-	assert.Equal(t, "hello.txt", entries[1].Name)
-	assert.Greater(t, entries[1].ModTime.Unix(), int64(0))
+	assert.Equal(t, "dir", entries[0].Name())
+	assert.True(t, entries[0].IsDir())
+	assert.Equal(t, "hello.txt", entries[1].Name())
+	assert.False(t, entries[1].IsDir())
+	info, err = entries[1].Info()
+	require.NoError(t, err)
+	assert.Greater(t, info.ModTime().Unix(), int64(0))
 
 	// Expect two entries in the directory.
 	entries, err = f.ReadDir(ctx, "/dir")
 	require.NoError(t, err)
 	assert.Len(t, entries, 2)
-	assert.Equal(t, "a", entries[0].Name)
-	assert.Equal(t, "world.txt", entries[1].Name)
-	assert.Greater(t, entries[1].ModTime.Unix(), int64(0))
+	assert.Equal(t, "a", entries[0].Name())
+	assert.True(t, entries[0].IsDir())
+	assert.Equal(t, "world.txt", entries[1].Name())
+	assert.False(t, entries[1].IsDir())
+	info, err = entries[1].Info()
+	require.NoError(t, err)
+	assert.Greater(t, info.ModTime().Unix(), int64(0))
 
 	// Expect a single entry in the nested path.
 	entries, err = f.ReadDir(ctx, "/dir/a/b")
 	require.NoError(t, err)
 	assert.Len(t, entries, 1)
-	assert.Equal(t, "c", entries[0].Name)
+	assert.Equal(t, "c", entries[0].Name())
+	assert.True(t, entries[0].IsDir())
 }
 
 func temporaryWorkspaceDir(t *testing.T, w *databricks.WorkspaceClient) string {

libs/filer/dbfs_client.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"io"
+	"io/fs"
 	"net/http"
 	"path"
 	"sort"
@@ -15,6 +16,52 @@ import (
 	"golang.org/x/exp/slices"
 )
 
+// Type that implements fs.DirEntry for DBFS.
+type dbfsDirEntry struct {
+	dbfsFileInfo
+}
+
+func (entry dbfsDirEntry) Type() fs.FileMode {
+	typ := fs.ModePerm
+	if entry.fi.IsDir {
+		typ |= fs.ModeDir
+	}
+	return typ
+}
+
+func (entry dbfsDirEntry) Info() (fs.FileInfo, error) {
+	return entry.dbfsFileInfo, nil
+}
+
+// Type that implements fs.FileInfo for DBFS.
+type dbfsFileInfo struct {
+	fi files.FileInfo
+}
+
+func (info dbfsFileInfo) Name() string {
+	return path.Base(info.fi.Path)
+}
+
+func (info dbfsFileInfo) Size() int64 {
+	return info.fi.FileSize
+}
+
+func (info dbfsFileInfo) Mode() fs.FileMode {
+	return fs.ModePerm
+}
+
+func (info dbfsFileInfo) ModTime() time.Time {
+	return time.UnixMilli(info.fi.ModificationTime)
+}
+
+func (info dbfsFileInfo) IsDir() bool {
+	return info.fi.IsDir
+}
+
+func (info dbfsFileInfo) Sys() any {
+	return nil
+}
+
 // DbfsClient implements the [Filer] interface for the DBFS backend.
 type DbfsClient struct {
 	workspaceClient *databricks.WorkspaceClient
@@ -152,7 +199,7 @@ func (w *DbfsClient) Delete(ctx context.Context, name string) error {
 	})
 }
 
-func (w *DbfsClient) ReadDir(ctx context.Context, name string) ([]FileInfo, error) {
+func (w *DbfsClient) ReadDir(ctx context.Context, name string) ([]fs.DirEntry, error) {
 	absPath, err := w.root.Join(name)
 	if err != nil {
 		return nil, err
@@ -175,17 +222,13 @@ func (w *DbfsClient) ReadDir(ctx context.Context, name string) ([]FileInfo, erro
 		return nil, err
 	}
 
-	info := make([]FileInfo, len(res.Files))
+	info := make([]fs.DirEntry, len(res.Files))
 	for i, v := range res.Files {
-		info[i] = FileInfo{
-			Name:    path.Base(v.Path),
-			Size:    v.FileSize,
-			ModTime: time.UnixMilli(v.ModificationTime),
-		}
+		info[i] = dbfsDirEntry{dbfsFileInfo: dbfsFileInfo{fi: v}}
 	}
 
 	// Sort by name for parity with os.ReadDir.
-	sort.Slice(info, func(i, j int) bool { return info[i].Name < info[j].Name })
+	sort.Slice(info, func(i, j int) bool { return info[i].Name() < info[j].Name() })
 	return info, nil
 }
 

libs/filer/filer.go

@@ -4,7 +4,7 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"time"
+	"io/fs"
 )
 
 type WriteMode int
@@ -14,22 +14,6 @@ const (
 	CreateParentDirectories           = iota << 1
 )
 
-// FileInfo abstracts over file information from different file systems.
-// Inspired by https://pkg.go.dev/io/fs#FileInfo.
-type FileInfo struct {
-	// The type of the file in workspace.
-	Type string
-
-	// Base name.
-	Name string
-
-	// Size in bytes.
-	Size int64
-
-	// Modification time.
-	ModTime time.Time
-}
-
 type FileAlreadyExistsError struct {
 	path string
 }
@@ -68,7 +52,7 @@ type Filer interface {
 	Delete(ctx context.Context, path string) error
 
 	// Return contents of directory at `path`.
-	ReadDir(ctx context.Context, path string) ([]FileInfo, error)
+	ReadDir(ctx context.Context, path string) ([]fs.DirEntry, error)
 
 	// Creates directory at `path`, creating any intermediate directories as required.
 	Mkdir(ctx context.Context, path string) error

libs/filer/workspace_files_client.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"net/http"
 	"net/url"
 	"path"
@@ -20,6 +21,53 @@ import (
 	"golang.org/x/exp/slices"
 )
 
+// Type that implements fs.DirEntry for WSFS.
+type wsfsDirEntry struct {
+	wsfsFileInfo
+}
+
+func (entry wsfsDirEntry) Type() fs.FileMode {
+	return entry.wsfsFileInfo.Mode()
+}
+
+func (entry wsfsDirEntry) Info() (fs.FileInfo, error) {
+	return entry.wsfsFileInfo, nil
+}
+
+// Type that implements fs.FileInfo for WSFS.
+type wsfsFileInfo struct {
+	oi workspace.ObjectInfo
+}
+
+func (info wsfsFileInfo) Name() string {
+	return path.Base(info.oi.Path)
+}
+
+func (info wsfsFileInfo) Size() int64 {
+	return info.oi.Size
+}
+
+func (info wsfsFileInfo) Mode() fs.FileMode {
+	switch info.oi.ObjectType {
+	case workspace.ObjectTypeDirectory:
+		return fs.ModeDir
+	default:
+		return fs.ModePerm
+	}
+}
+
+func (info wsfsFileInfo) ModTime() time.Time {
+	return time.UnixMilli(info.oi.ModifiedAt)
+}
+
+func (info wsfsFileInfo) IsDir() bool {
+	return info.oi.ObjectType == workspace.ObjectTypeDirectory
+}
+
+func (info wsfsFileInfo) Sys() any {
+	return nil
+}
+
 // WorkspaceFilesClient implements the files-in-workspace API.
 
 // NOTE: This API is available for files under /Repos if a workspace has files-in-repos enabled.
@@ -165,7 +213,7 @@ func (w *WorkspaceFilesClient) Delete(ctx context.Context, name string) error {
 	return err
 }
 
-func (w *WorkspaceFilesClient) ReadDir(ctx context.Context, name string) ([]FileInfo, error) {
+func (w *WorkspaceFilesClient) ReadDir(ctx context.Context, name string) ([]fs.DirEntry, error) {
 	absPath, err := w.root.Join(name)
 	if err != nil {
 		return nil, err
@@ -189,18 +237,13 @@ func (w *WorkspaceFilesClient) ReadDir(ctx context.Context, name string) ([]File
 		return nil, err
 	}
 
-	info := make([]FileInfo, len(objects))
+	info := make([]fs.DirEntry, len(objects))
 	for i, v := range objects {
-		info[i] = FileInfo{
-			Type:    string(v.ObjectType),
-			Name:    path.Base(v.Path),
-			Size:    v.Size,
-			ModTime: time.UnixMilli(v.ModifiedAt),
-		}
+		info[i] = wsfsDirEntry{wsfsFileInfo{oi: v}}
 	}
 
 	// Sort by name for parity with os.ReadDir.
-	sort.Slice(info, func(i, j int) bool { return info[i].Name < info[j].Name })
+	sort.Slice(info, func(i, j int) bool { return info[i].Name() < info[j].Name() })
 	return info, nil
 }