Implement ReadDir

Signed-off-by: jolheiser <john.olheiser@gmail.com>

overlay.go

@@ -39,6 +39,12 @@ func (f *FS) Open(name string) (fs.File, error) {
 	return f.fs.Open(name)
 }
 
+// ReadDir reads []fs.DirEntry
+// This method will prefer EMBEDDED, because that is the "real" FS for overlay
+func (f *FS) ReadDir(name string) ([]fs.DirEntry, error) {
+	return fs.ReadDir(f.fs, name)
+}
+
 // Option is a functional option for an FS
 type Option func(*FS) error
 

overlay_test.go

@@ -3,6 +3,7 @@ package overlay
 import (
 	"embed"
 	"io"
+	"io/fs"
 	"os"
 	"strings"
 	"testing"
@@ -62,6 +63,48 @@ func TestOverlay(t *testing.T) {
 	}
 }
 
+func TestWalk(t *testing.T) {
+	expected := []string{"test1.txt", "test2.txt"}
+
+	x, err := New("_test/disk", embedded, WithSub("_test/embed"), WithCaching(false))
+	if err != nil {
+		t.Log(err)
+		t.FailNow()
+	}
+
+	found := make([]string, 0)
+	if err := fs.WalkDir(x, ".", func(walkPath string, walkEntry fs.DirEntry, walkErr error) error {
+		if walkErr != nil {
+			return walkErr
+		}
+
+		if walkEntry.IsDir() {
+			return nil
+		}
+
+		found = append(found, walkEntry.Name())
+
+		return nil
+	}); err != nil {
+		t.Log(err)
+		t.FailNow()
+	}
+
+	for _, e := range expected {
+		exists := false
+		for _, f := range found {
+			if e == f {
+				exists = true
+				break
+			}
+		}
+		if !exists {
+			t.Logf("could not find %s in %s\n", e, found)
+			t.Fail()
+		}
+	}
+}
+
 var emptyFS embed.FS
 
 func TestInvalid(t *testing.T) {