add testcase & changelog

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - [#1982](https://github.com/influxdata/kapacitor/pull/1982): Fix KafkaTopic not working from TICKscript
 - [#1989](https://github.com/influxdata/kapacitor/pull/1989): Improve Kafka alert throughput.
+- [#1980](https://github.com/influxdata/kapacitor/pull/1980): Fix discovery service lost config.
 
 ## v1.5.0 [2018-05-17]
 

services/scraper/config_test.go

@@ -0,0 +1,55 @@
+package scraper_test
+
+import (
+	"testing"
+
+	"github.com/influxdata/kapacitor/services/file_discovery"
+	"github.com/influxdata/kapacitor/services/scraper"
+	"github.com/prometheus/common/log"
+)
+
+func TestConfig_MultiConfig(t *testing.T) {
+	tests := []struct {
+		name            string
+		discoveryConfig []file_discovery.Config
+		scraperConfig   []scraper.Config
+	}{
+		{
+			name: "first discovery config in multi config",
+			discoveryConfig: []file_discovery.Config{
+				{
+					Enabled: true,
+					ID:      "first",
+				},
+				{
+					Enabled: true,
+					ID:      "second",
+				},
+			},
+			scraperConfig: []scraper.Config{
+				{
+					Enabled:         true,
+					DiscoverID:      "first",
+					DiscoverService: file_discovery.Config{}.Service(),
+				},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		diag := scraper.Diagnostic(log.NewNopLogger())
+		for i := range tt.discoveryConfig {
+			tt.discoveryConfig[i].Init()
+		}
+		registy := scraper.NewService(tt.scraperConfig, diag)
+		registy.Open()
+		svc := file_discovery.NewService(tt.discoveryConfig, registy, diag)
+		svc.Open()
+		pairs := registy.Pairs()
+		if len(pairs) == 0 {
+			t.Errorf("cannot register discovery config: %s", tt.name)
+		}
+		svc.Close()
+		registy.Close()
+	}
+}