From a48bf3f8566559660c11fa0f08a09914a37214f1 Mon Sep 17 00:00:00 2001
From: Eyal Posener <posener@gmail.com>
Date: Fri, 22 Nov 2019 14:58:47 +0200
Subject: [PATCH] Options: add tests

---
 predict/options.go | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/predict/options.go b/predict/options.go
index 1c34feb..8d88b54 100644
--- a/predict/options.go
+++ b/predict/options.go
@@ -23,12 +23,22 @@ func OptValues(values ...string) Option {
 
 // OptPredictor allows to set a custom predictor.
 func OptPredictor(p complete.Predictor) Option {
-	return func(o *Config) { o.Predictor = p }
+	return func(o *Config) {
+		if o.Predictor != nil {
+			panic("predictor set more than once.")
+		}
+		o.Predictor = p
+	}
 }
 
 // OptCheck enforces the valid values on the predicted flag.
 func OptCheck() Option {
-	return func(o *Config) { o.check = true }
+	return func(o *Config) {
+		if o.check {
+			panic("check set more than once")
+		}
+		o.check = true
+	}
 }
 
 type Config struct {