Fix Err fallout for graph/iterator.Or iterator

graph/iterator/or_iterator.go

@@ -33,6 +33,7 @@ type Or struct {
 	itCount           int
 	currentIterator   int
 	result            graph.Value
+	err               error
 }
 
 func NewOr() *Or {
@@ -147,6 +148,11 @@ func (it *Or) Next() bool {
 			return graph.NextLogOut(it, it.result, true)
 		}
 
+		if err := graph.Err(curIt); err != nil {
+			it.err = err
+			return graph.NextLogOut(it, nil, false)
+		}
+
 		if it.isShortCircuiting && !first {
 			break
 		}
@@ -159,6 +165,10 @@ func (it *Or) Next() bool {
 	return graph.NextLogOut(it, nil, false)
 }
 
+func (it *Or) Err() error {
+	return it.err
+}
+
 func (it *Or) Result() graph.Value {
 	return it.result
 }

graph/iterator/or_iterator_test.go

@@ -15,6 +15,7 @@
 package iterator
 
 import (
+	"errors"
 	"reflect"
 	"testing"
 
@@ -148,3 +149,46 @@ func TestShortCircuitingOrBasics(t *testing.T) {
 		t.Errorf("Failed to iterate optimized Or correctly, got:%v expect:%v", got, expect)
 	}
 }
+
+func TestOrIteratorErr(t *testing.T) {
+	retErr := errors.New("unique")
+	orErr := newTestIterator(false, retErr)
+
+	fix1 := NewFixed(Identity)
+	fix1.Add(1)
+
+	or := NewOr()
+	or.AddSubIterator(fix1)
+	or.AddSubIterator(orErr)
+	or.AddSubIterator(NewInt64(1, 5))
+
+	if !or.Next() {
+		t.Errorf("Failed to iterate Or correctly")
+	}
+	if got := or.Result(); got != 1 {
+		t.Errorf("Failed to iterate Or correctly, got:%v expect:1", got)
+	}
+
+	if or.Next() != false {
+		t.Errorf("Or iterator did not pass through underlying 'false'")
+	}
+	if or.Err() != retErr {
+		t.Errorf("Or iterator did not pass through underlying Err")
+	}
+}
+
+func TestShortCircuitOrIteratorErr(t *testing.T) {
+	retErr := errors.New("unique")
+	orErr := newTestIterator(false, retErr)
+
+	or := NewOr()
+	or.AddSubIterator(orErr)
+	or.AddSubIterator(NewInt64(1, 5))
+
+	if or.Next() != false {
+		t.Errorf("Or iterator did not pass through underlying 'false'")
+	}
+	if or.Err() != retErr {
+		t.Errorf("Or iterator did not pass through underlying Err")
+	}
+}