Don't throw an error on a missing folder in localfs (#95)

Co-authored-by: Erin Pentecost <erin.pentecost@lytics.com>

Author: erinpentecost

localfs/store.go

@@ -197,7 +197,7 @@ func (l *LocalStore) Objects(ctx context.Context, csq cloudstorage.Query) (cloud
 func (l *LocalStore) Folders(ctx context.Context, csq cloudstorage.Query) ([]string, error) {
 	spath := path.Join(l.storepath, csq.Prefix)
 	if !cloudstorage.Exists(spath) {
-		return nil, fmt.Errorf("That folder %q does not exist", spath)
+		return []string{}, nil
 	}
 	select {
 	case <-ctx.Done():

testutils/testutils.go

@@ -643,6 +643,16 @@ func ListObjsAndFolders(t TestingT, store cloudstorage.Store) {
 	folders, err = store.Folders(ctx, q)
 	assert.NotEqual(t, nil, err)
 	assert.Equal(t, 0, len(folders), "incorrect list len. wanted 0 folders. %v", folders)
+
+	// List objects from a missing folder
+	q = cloudstorage.NewQuery("does-not-exist/")
+	resp, err := store.List(context.Background(), q)
+	assert.NoError(t, err)
+	assert.NotNil(t, resp)
+	assert.Empty(t, resp.Objects)
+	folders, err = store.Folders(context.Background(), q)
+	assert.NoError(t, err)
+	assert.Empty(t, folders)
 }
 
 func Truncate(t TestingT, store cloudstorage.Store) {