Merge pull request #45 from sg3-141-592/negative-step-check

Fix for negative step in cron expression

Author: adhocore

gronx_test.go

@@ -91,6 +91,9 @@ func TestIsValid(t *testing.T) {
 		if gron.IsValid("* * * *") {
 			t.Errorf("expected false, got true")
 		}
+		if gron.IsValid("0-0/-005 * * * *") {
+			t.Errorf("expected true, got false")
+		}
 	})
 
 }

validator.go

@@ -14,7 +14,7 @@ func inStep(val int, s string, bounds []int) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	if step == 0 {
+	if step <= 0 {
 		return false, errors.New("step can't be 0")
 	}