fix: UnionFile.Readdir now returns all entries when count <= 0 (fixes…

unionFile.go

@@ -156,7 +156,7 @@ var defaultUnionMergeDirsFn = func(lofi, bofi []os.FileInfo) ([]os.FileInfo, err
 // Readdir will weave the two directories together and
 // return a single view of the overlayed directories.
 // At the end of the directory view, the error is io.EOF if c > 0.
-func (f *UnionFile) Readdir(c int) (ofi []os.FileInfo, err error) {
+func (f *UnionFile) Readdir(count int) (ofi []os.FileInfo, err error) {
 	var merge DirsMerger = f.Merger
 	if merge == nil {
 		merge = defaultUnionMergeDirsFn
@@ -177,7 +177,6 @@ func (f *UnionFile) Readdir(c int) (ofi []os.FileInfo, err error) {
 			if err != nil {
 				return nil, err
 			}
-
 		}
 		merged, err := merge(lfi, bfi)
 		if err != nil {
@@ -187,20 +186,21 @@ func (f *UnionFile) Readdir(c int) (ofi []os.FileInfo, err error) {
 	}
 	files := f.files[f.off:]
 
-	if c <= 0 {
+	// Fixed: Check count <= 0 instead of c != -1
+	if count <= 0 {
 		return files, nil
 	}
 
 	if len(files) == 0 {
 		return nil, io.EOF
 	}
 
-	if c > len(files) {
-		c = len(files)
+	if count > len(files) {
+		count = len(files)
 	}
 
-	defer func() { f.off += c }()
-	return files[:c], nil
+	defer func() { f.off += count }()
+	return files[:count], nil
 }
 
 func (f *UnionFile) Readdirnames(c int) ([]string, error) {

unionFile_test.go

@@ -0,0 +1,84 @@
+package afero
+
+import (
+	"io"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUnionFileReaddir(t *testing.T) {
+	// Setup
+	baseFs := NewMemMapFs()
+	overlayFs := NewMemMapFs()
+
+	assert.NoError(t, baseFs.Mkdir("testdir", 0755))
+	assert.NoError(t, overlayFs.Mkdir("testdir", 0755))
+
+	_, err := baseFs.Create("testdir/base1.txt")
+	assert.NoError(t, err)
+	_, err = baseFs.Create("testdir/base2.txt")
+	assert.NoError(t, err)
+	_, err = overlayFs.Create("testdir/base1.txt")
+	assert.NoError(t, err)
+	_, err = overlayFs.Create("testdir/over1.txt")
+	assert.NoError(t, err)
+
+	ufs := NewUnionFs(baseFs, overlayFs)
+	dir, err := ufs.Open("testdir")
+	assert.NoError(t, err)
+	defer dir.Close()
+
+	tests := []struct {
+		name      string
+		count     int
+		wantCount int
+		wantNames []string
+		wantErr   error
+	}{
+		{
+			name:      "Read all with -1",
+			count:     -1,
+			wantCount: 3,
+			wantNames: []string{"base1.txt", "base2.txt", "over1.txt"},
+			wantErr:   nil,
+		},
+		{
+			name:      "Read all with 0",
+			count:     0,
+			wantCount: 3,
+			wantNames: []string{"base1.txt", "base2.txt", "over1.txt"},
+			wantErr:   nil,
+		},
+		{
+			name:      "Read 1 entry",
+			count:     1,
+			wantCount: 1,
+			wantNames: []string{"base1.txt"},
+			wantErr:   nil,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			uf := dir.(*UnionFile)
+			uf.off = 0
+			uf.files = nil // Reset for each test
+
+			infos, err := dir.Readdir(tt.count)
+			if tt.wantErr != nil {
+				assert.Equal(t, tt.wantErr, err)
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.wantCount, len(infos))
+
+				var gotNames []string
+				for _, info := range infos {
+					gotNames = append(gotNames, info.Name())
+				}
+				assert.ElementsMatch(t, tt.wantNames, gotNames)
+			}
+		})
+	}
+}