fix panic in MultiSearch when all indexes return error

fixes #126

index_alias_impl.go

@@ -401,6 +401,12 @@ func MultiSearch(req *SearchRequest, indexes ...Index) (*SearchResult, error) {
 		}
 	}
 
+	// for now stop on any error
+	// FIXME offer other behaviors
+	if err != nil {
+		return nil, err
+	}
+
 	// merge just concatenated all the hits
 	// now lets clean it up
 
@@ -426,11 +432,5 @@ func MultiSearch(req *SearchRequest, indexes ...Index) (*SearchResult, error) {
 		sr.Facets.Fixup(name, fr.Size)
 	}
 
-	// for now stop on any error
-	// FIXME offer other behaviors
-	if err != nil {
-		return nil, err
-	}
-
 	return sr, nil
 }

index_alias_impl_test.go

@@ -0,0 +1,90 @@
+package bleve
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/blevesearch/bleve/document"
+)
+
+// TestMultiSearchAllError
+// reproduces https://github.com/blevesearch/bleve/issues/126
+func TestMultiSearchAllError(t *testing.T) {
+	ei1 := &errIndex{err: fmt.Errorf("deliberate error")}
+	ei2 := &errIndex{err: fmt.Errorf("deliberate errro")}
+	sr := NewSearchRequest(NewTermQuery("test"))
+	_, err := MultiSearch(sr, ei1, ei2)
+	if err == nil {
+		t.Errorf("expected error, got %v", err)
+	}
+}
+
+// errIndex is an Index impl for which all operations
+// return the configured error value
+type errIndex struct {
+	err error
+}
+
+func (i *errIndex) Index(id string, data interface{}) error {
+	return i.err
+}
+
+func (i *errIndex) Delete(id string) error {
+	return i.err
+}
+
+func (i *errIndex) Batch(b *Batch) error {
+	return i.err
+}
+
+func (i *errIndex) Document(id string) (*document.Document, error) {
+	return nil, i.err
+}
+
+func (i *errIndex) DocCount() (uint64, error) {
+	return 0, i.err
+}
+
+func (i *errIndex) Search(req *SearchRequest) (*SearchResult, error) {
+	return nil, i.err
+}
+
+func (i *errIndex) Fields() ([]string, error) {
+	return nil, i.err
+}
+
+func (i *errIndex) DumpAll() chan interface{} {
+	return nil
+}
+
+func (i *errIndex) DumpDoc(id string) chan interface{} {
+	return nil
+}
+
+func (i *errIndex) DumpFields() chan interface{} {
+	return nil
+}
+
+func (i *errIndex) Close() error {
+	return i.err
+}
+
+func (i *errIndex) Mapping() *IndexMapping {
+	return nil
+}
+
+func (i *errIndex) Stats() *IndexStat {
+	return nil
+}
+
+func (i *errIndex) GetInternal(key []byte) ([]byte, error) {
+	return nil, i.err
+}
+
+func (i *errIndex) SetInternal(key, val []byte) error {
+	return i.err
+}
+
+func (i *errIndex) DeleteInternal(key []byte) error {
+	return i.err
+}