test: Improve test coverage (#289)

* test: Test `NewReader()`

* test: Test `fileReadCloser.Seek()`

* refactor: Change `io/fs` import

* refactor: Use afero for filesystem interactions

* test: Test `openReader()`

export_test.go

@@ -1,3 +1,6 @@
 package sevenzip
 
-var ErrMissingUnpackInfo = errMissingUnpackInfo
+var (
+	ErrMissingUnpackInfo = errMissingUnpackInfo
+	ErrNegativeSize      = errNegativeSize
+)

go.mod

@@ -9,6 +9,7 @@ require (
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/klauspost/compress v1.17.11
 	github.com/pierrec/lz4/v4 v4.1.21
+	github.com/spf13/afero v1.11.0
 	github.com/stretchr/testify v1.9.0
 	github.com/ulikunitz/xz v0.5.12
 	go4.org v0.0.0-20200411211856-f5505b9728dd
@@ -19,5 +20,6 @@ require (
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/objx v0.5.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -82,9 +82,13 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/prometheus/client_model v0.0.0-20190812154241-14fe0d1b01d4/go.mod h1:xMI15A0UPsDsEKsMN9yxemIoYk6Tm2C1GtYGdfGttqA=
 github.com/rogpeppe/go-internal v1.3.0/go.mod h1:M8bDsm7K2OlrFYOpmOWEs/qY81heoFRclV5y23lUDJ4=
 github.com/rwcarlsen/goexif v0.0.0-20190401172101-9e8deecbddbd/go.mod h1:hPqNNc0+uJM6H+SuU8sEs5K5IQeKccPqeSjfgcKGgPk=
+github.com/spf13/afero v1.11.0 h1:WJQKhtpdm3v2IzqG8VMqrr6Rf3UYpEF239Jy9wNepM8=
+github.com/spf13/afero v1.11.0/go.mod h1:GH9Y3pIexgf1MTIWtNGyogA5MwRIDXGUr+hbWNoBjkY=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
 github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
+github.com/stretchr/objx v0.5.2 h1:xuMeJ0Sdp5ZMRXx/aWO6RZxdr3beISkG5/G/aIRr3pY=
+github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/8L+MA=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=

reader.go

@@ -9,8 +9,7 @@ import (
 	"fmt"
 	"hash/crc32"
 	"io"
-	"io/fs"
-	"os"
+	iofs "io/fs"
 	"path"
 	"path/filepath"
 	"sort"
@@ -21,6 +20,7 @@ import (
 	"github.com/bodgit/plumbing"
 	"github.com/bodgit/sevenzip/internal/pool"
 	"github.com/bodgit/sevenzip/internal/util"
+	"github.com/spf13/afero"
 	"go4.org/readerutil"
 )
 
@@ -63,7 +63,7 @@ type Reader struct {
 
 // A ReadCloser is a [Reader] that must be closed when no longer needed.
 type ReadCloser struct {
-	f []*os.File
+	f []afero.File
 	Reader
 }
 
@@ -83,7 +83,7 @@ type fileReader struct {
 	n  int64
 }
 
-func (fr *fileReader) Stat() (fs.FileInfo, error) {
+func (fr *fileReader) Stat() (iofs.FileInfo, error) {
 	return headerFileInfo{&fr.f.FileHeader}, nil
 }
 
@@ -187,37 +187,31 @@ func (f *File) Open() (io.ReadCloser, error) {
 	}, nil
 }
 
-// OpenReaderWithPassword will open the 7-zip file specified by name using
-// password as the basis of the decryption key and return a [*ReadCloser]. If
-// name has a ".001" suffix it is assumed there are multiple volumes and each
-// sequential volume will be opened.
-//
-//nolint:cyclop,funlen
-func OpenReaderWithPassword(name, password string) (*ReadCloser, error) {
-	f, err := os.Open(filepath.Clean(name))
+func openReader(fs afero.Fs, name string) (io.ReaderAt, int64, []afero.File, error) {
+	f, err := fs.Open(filepath.Clean(name))
 	if err != nil {
-		return nil, fmt.Errorf("sevenzip: error opening: %w", err)
+		return nil, 0, nil, fmt.Errorf("sevenzip: error opening: %w", err)
 	}
 
 	info, err := f.Stat()
 	if err != nil {
 		err = errors.Join(err, f.Close())
 
-		return nil, fmt.Errorf("sevenzip: error retrieving file info: %w", err)
+		return nil, 0, nil, fmt.Errorf("sevenzip: error retrieving file info: %w", err)
 	}
 
 	var reader io.ReaderAt = f
 
 	size := info.Size()
-	files := []*os.File{f}
+	files := []afero.File{f}
 
 	if ext := filepath.Ext(name); ext == ".001" {
 		sr := []readerutil.SizeReaderAt{io.NewSectionReader(f, 0, size)}
 
 		for i := 2; true; i++ {
-			f, err := os.Open(fmt.Sprintf("%s.%03d", strings.TrimSuffix(name, ext), i))
+			f, err := fs.Open(fmt.Sprintf("%s.%03d", strings.TrimSuffix(name, ext), i))
 			if err != nil {
-				if errors.Is(err, fs.ErrNotExist) {
+				if errors.Is(err, iofs.ErrNotExist) {
 					break
 				}
 
@@ -228,7 +222,7 @@ func OpenReaderWithPassword(name, password string) (*ReadCloser, error) {
 					errs = append(errs, file.Close())
 				}
 
-				return nil, fmt.Errorf("sevenzip: error opening: %w", errors.Join(errs...))
+				return nil, 0, nil, fmt.Errorf("sevenzip: error opening: %w", errors.Join(errs...))
 			}
 
 			files = append(files, f)
@@ -242,7 +236,7 @@ func OpenReaderWithPassword(name, password string) (*ReadCloser, error) {
 					errs = append(errs, file.Close())
 				}
 
-				return nil, fmt.Errorf("sevenzip: error retrieving file info: %w", errors.Join(errs...))
+				return nil, 0, nil, fmt.Errorf("sevenzip: error retrieving file info: %w", errors.Join(errs...))
 			}
 
 			sr = append(sr, io.NewSectionReader(f, 0, info.Size()))
@@ -252,6 +246,19 @@ func OpenReaderWithPassword(name, password string) (*ReadCloser, error) {
 		reader, size = mr, mr.Size()
 	}
 
+	return reader, size, files, nil
+}
+
+// OpenReaderWithPassword will open the 7-zip file specified by name using
+// password as the basis of the decryption key and return a [*ReadCloser]. If
+// name has a ".001" suffix it is assumed there are multiple volumes and each
+// sequential volume will be opened.
+func OpenReaderWithPassword(name, password string) (*ReadCloser, error) {
+	reader, size, files, err := openReader(afero.NewOsFs(), name)
+	if err != nil {
+		return nil, err
+	}
+
 	r := new(ReadCloser)
 	r.p = password
 
@@ -582,8 +589,8 @@ type fileListEntry struct {
 }
 
 type fileInfoDirEntry interface {
-	fs.FileInfo
-	fs.DirEntry
+	iofs.FileInfo
+	iofs.DirEntry
 }
 
 func (e *fileListEntry) stat() (fileInfoDirEntry, error) {
@@ -604,11 +611,11 @@ func (e *fileListEntry) Name() string {
 	return elem
 }
 
-func (e *fileListEntry) Size() int64       { return 0 }
-func (e *fileListEntry) Mode() fs.FileMode { return fs.ModeDir | 0o555 }
-func (e *fileListEntry) Type() fs.FileMode { return fs.ModeDir }
-func (e *fileListEntry) IsDir() bool       { return true }
-func (e *fileListEntry) Sys() interface{}  { return nil }
+func (e *fileListEntry) Size() int64         { return 0 }
+func (e *fileListEntry) Mode() iofs.FileMode { return iofs.ModeDir | 0o555 }
+func (e *fileListEntry) Type() iofs.FileMode { return iofs.ModeDir }
+func (e *fileListEntry) IsDir() bool         { return true }
+func (e *fileListEntry) Sys() interface{}    { return nil }
 
 func (e *fileListEntry) ModTime() time.Time {
 	if e.file == nil {
@@ -618,7 +625,7 @@ func (e *fileListEntry) ModTime() time.Time {
 	return e.file.FileHeader.Modified.UTC()
 }
 
-func (e *fileListEntry) Info() (fs.FileInfo, error) { return e, nil }
+func (e *fileListEntry) Info() (iofs.FileInfo, error) { return e, nil }
 
 func toValidName(name string) string {
 	name = strings.ReplaceAll(name, `\`, `/`)
@@ -708,16 +715,16 @@ func fileEntryLess(x, y string) bool {
 // Open opens the named file in the 7-zip archive, using the semantics of
 // [fs.FS.Open]: paths are always slash separated, with no leading / or ../
 // elements.
-func (z *Reader) Open(name string) (fs.File, error) {
+func (z *Reader) Open(name string) (iofs.File, error) {
 	z.initFileList()
 
-	if !fs.ValidPath(name) {
-		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrInvalid}
+	if !iofs.ValidPath(name) {
+		return nil, &iofs.PathError{Op: "open", Path: name, Err: iofs.ErrInvalid}
 	}
 
 	e := z.openLookup(name)
 	if e == nil {
-		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
+		return nil, &iofs.PathError{Op: "open", Path: name, Err: iofs.ErrNotExist}
 	}
 
 	if e.isDir {
@@ -729,7 +736,7 @@ func (z *Reader) Open(name string) (fs.File, error) {
 		return nil, err
 	}
 
-	return rc.(fs.File), nil //nolint:forcetypeassert
+	return rc.(iofs.File), nil //nolint:forcetypeassert
 }
 
 func split(name string) (dir, elem string) {
@@ -800,16 +807,16 @@ type openDir struct {
 	offset int
 }
 
-func (d *openDir) Close() error               { return nil }
-func (d *openDir) Stat() (fs.FileInfo, error) { return d.e.stat() }
+func (d *openDir) Close() error                 { return nil }
+func (d *openDir) Stat() (iofs.FileInfo, error) { return d.e.stat() }
 
 var errIsDirectory = errors.New("is a directory")
 
 func (d *openDir) Read([]byte) (int, error) {
-	return 0, &fs.PathError{Op: "read", Path: d.e.name, Err: errIsDirectory}
+	return 0, &iofs.PathError{Op: "read", Path: d.e.name, Err: errIsDirectory}
 }
 
-func (d *openDir) ReadDir(count int) ([]fs.DirEntry, error) {
+func (d *openDir) ReadDir(count int) ([]iofs.DirEntry, error) {
 	n := len(d.files) - d.offset
 	if count > 0 && n > count {
 		n = count
@@ -823,7 +830,7 @@ func (d *openDir) ReadDir(count int) ([]fs.DirEntry, error) {
 		return nil, io.EOF
 	}
 
-	list := make([]fs.DirEntry, n)
+	list := make([]iofs.DirEntry, n)
 	for i := range list {
 		s, err := d.files[d.offset+i].stat()
 		if err != nil {