check: Add JSON marshalling

check/check.go

@@ -1,6 +1,7 @@
 package check
 
 import (
+	"encoding/json"
 	"time"
 )
 
@@ -32,3 +33,19 @@ func statusFromSuccessCount(count int) Result {
 func divide(t time.Duration, dividend int) time.Duration {
 	return time.Duration(int(t) / dividend)
 }
+
+func (r Result) String() string {
+	switch r {
+	case Online:
+		return "online"
+	case Unstable:
+		return "unstable"
+	case Offline:
+		return "offline"
+	}
+	panic("Unexpected value")
+}
+
+func (r Result) MarshalJSON() ([]byte, error) {
+	return json.Marshal(r.String())
+}