refactor: use fs.FS for aggregate and DB import (ask v3)

Decouple Aggregator and ImportFromDir from direct os.Open by routing
through io/fs: NewAggregatorFS, ImportFromFS, recordsdir.ListNonEmptyFilesFS.
NewAggregator and ImportFromDir wrap os.DirFS for backward compatibility.

Add fstest.MapFS tests for recordsdir, aggregate, and ImportFromFS.

Made-with: Cursor

2 files changed, 55 insertions, 6 deletions

diff --git a/internal/recordsdir/recordsdir.go b/internal/recordsdir/recordsdir.go
index 9f3ce5b..94f7f0e 100644
--- a/internal/recordsdir/recordsdir.go
+++ b/internal/recordsdir/recordsdir.go
@@ -1,7 +1,9 @@
 package recordsdir
 
 import (
+	"io/fs"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 )
@@ -19,22 +21,53 @@ func HostFromFileName(name string) string {
 	return host
 }
 
-func ListNonEmptyFiles(dir string) ([]Entry, error) {
-	entries, err := os.ReadDir(dir)
+func listRecordsFileNames(fsys fs.FS, root string) ([]string, error) {
+	entries, err := fs.ReadDir(fsys, root)
 	if err != nil {
 		return nil, err
 	}
-	var out []Entry
+	var names []string
 	for _, e := range entries {
 		if e.IsDir() || !strings.HasSuffix(e.Name(), ".records") {
 			continue
 		}
-		path := filepath.Join(dir, e.Name())
-		info, err := os.Stat(path)
+		rel := path.Join(root, e.Name())
+		info, err := fs.Stat(fsys, rel)
 		if err != nil || info.Size() == 0 {
 			continue
 		}
-		out = append(out, Entry{Path: path, Host: HostFromFileName(e.Name())})
+		names = append(names, e.Name())
+	}
+	return names, nil
+}
+
+// ListNonEmptyFilesFS returns non-empty .records files under root within fsys.
+func ListNonEmptyFilesFS(fsys fs.FS, root string) ([]Entry, error) {
+	names, err := listRecordsFileNames(fsys, root)
+	if err != nil {
+		return nil, err
+	}
+	var out []Entry
+	for _, name := range names {
+		out = append(out, Entry{
+			Path: path.Join(root, name),
+			Host: HostFromFileName(name),
+		})
+	}
+	return out, nil
+}
+
+func ListNonEmptyFiles(dir string) ([]Entry, error) {
+	names, err := listRecordsFileNames(os.DirFS(dir), ".")
+	if err != nil {
+		return nil, err
+	}
+	var out []Entry
+	for _, name := range names {
+		out = append(out, Entry{
+			Path: filepath.Join(dir, name),
+			Host: HostFromFileName(name),
+		})
 	}
 	return out, nil
 }
diff --git a/internal/recordsdir/recordsdir_test.go b/internal/recordsdir/recordsdir_test.go
index bee8d67..5e72d9d 100644
--- a/internal/recordsdir/recordsdir_test.go
+++ b/internal/recordsdir/recordsdir_test.go
@@ -4,6 +4,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"testing/fstest"
 )
 
 func TestHostFromFileName(t *testing.T) {
@@ -56,3 +57,18 @@ func TestListNonEmptyFiles_ReadError(t *testing.T) {
 		t.Fatal("expected error")
 	}
 }
+
+func TestListNonEmptyFilesFS_MapFS(t *testing.T) {
+	m := fstest.MapFS{
+		"skip.txt":      &fstest.MapFile{Data: []byte("x"), Mode: 0o644},
+		"empty.records": &fstest.MapFile{Data: nil, Mode: 0o644},
+		"h1.records":    &fstest.MapFile{Data: []byte("line\n"), Mode: 0o644},
+	}
+	entries, err := ListNonEmptyFilesFS(m, ".")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(entries) != 1 || entries[0].Host != "h1" || entries[0].Path != "h1.records" {
+		t.Fatalf("got %#v", entries)
+	}
+}