brake the start provider func so that can run unit tests against it.

discovery/manager.go

@@ -103,12 +103,22 @@ func (m *Manager) ApplyConfig(cfg *config.Config) error {
 		m.cancelDiscoverers()
 		for _, scfg := range cfg.ScrapeConfigs {
 			for provName, prov := range m.providersFromConfig(scfg.ServiceDiscoveryConfig) {
+				m.startProvider(scfg.JobName, provName, prov)
+			}
+		}
+		close(err)
+	}
+
+	return <-err
+}
+
+func (m *Manager) startProvider(jobName, provName string, worker Discoverer) {
 	ctx, cancel := context.WithCancel(m.ctx)
 	updates := make(chan []*config.TargetGroup)
 
 	m.discoverCancel = append(m.discoverCancel, cancel)
 
-				go prov.Run(ctx, updates)
+	go worker.Run(ctx, updates)
 	go func(provName string) {
 		select {
 		case <-ctx.Done():
@@ -119,7 +129,7 @@ func (m *Manager) ApplyConfig(cfg *config.Config) error {
 			if !ok {
 				break
 			}
-						m.syncCh <- m.mergeGroups(scfg.JobName, provName, tgs)
+			m.syncCh <- m.mergeGroups(jobName, provName, tgs)
 		case <-time.After(5 * time.Second):
 			// Initial set didn't arrive. Act as if it was empty
 			// and wait for updates later on.
@@ -136,16 +146,10 @@ func (m *Manager) ApplyConfig(cfg *config.Config) error {
 				if !ok {
 					return
 				}
-							m.syncCh <- m.mergeGroups(scfg.JobName, provName, tgs)
+				m.syncCh <- m.mergeGroups(jobName, provName, tgs)
 			}
 		}
 	}(provName)
-			}
-		}
-		close(err)
-	}
-
-	return <-err
 }
 
 func (m *Manager) cancelDiscoverers() {