Propose a test

internal/component/prometheus/operator/common/component.go

@@ -19,14 +19,16 @@ import (
 type Component struct {
 	mut     sync.RWMutex
 	config  *operator.Arguments
-	manager *crdManager
+	manager crdManagerInterface
 	ls      labelstore.LabelStore
 
 	onUpdate  chan struct{}
 	opts      component.Options
 	healthMut sync.RWMutex
 	health    component.Health
 
+	crdManagerFactory crdManagerFactory
+
 	kind    string
 	cluster cluster.Cluster
 }
@@ -44,11 +46,12 @@ func New(o component.Options, args component.Arguments, kind string) (*Component
 	}
 	ls := service.(labelstore.LabelStore)
 	c := &Component{
-		opts:     o,
-		onUpdate: make(chan struct{}, 1),
-		kind:     kind,
-		cluster:  clusterData,
-		ls:       ls,
+		opts:              o,
+		onUpdate:          make(chan struct{}, 1),
+		kind:              kind,
+		cluster:           clusterData,
+		ls:                ls,
+		crdManagerFactory: realCrdManagerFactory{},
 	}
 	return c, c.Update(args)
 }
@@ -87,7 +90,7 @@ func (c *Component) Run(ctx context.Context) error {
 			c.reportHealth(err)
 		case <-c.onUpdate:
 			c.mut.Lock()
-			manager := newCrdManager(c.opts, c.cluster, c.opts.Logger, c.config, c.kind, c.ls)
+			manager := c.crdManagerFactory.New(c.opts, c.cluster, c.opts.Logger, c.config, c.kind, c.ls)
 			c.manager = manager
 
 			// Wait for the old manager to stop.
@@ -180,7 +183,7 @@ func (c *Component) Handler() http.Handler {
 		}
 		ns := parts[1]
 		name := parts[2]
-		scs := man.getScrapeConfig(ns, name)
+		scs := man.GetScrapeConfig(ns, name)
 		if len(scs) == 0 {
 			w.WriteHeader(404)
 			return

internal/component/prometheus/operator/common/crdmanager.go

@@ -40,6 +40,23 @@ import (
 // Generous timeout period for configuring all informers
 const informerSyncTimeout = 10 * time.Second
 
+type crdManagerInterface interface {
+	Run(ctx context.Context) error
+	ClusteringUpdated()
+	DebugInfo() interface{}
+	GetScrapeConfig(ns, name string) []*config.ScrapeConfig
+}
+
+type crdManagerFactory interface {
+	New(opts component.Options, cluster cluster.Cluster, logger log.Logger, args *operator.Arguments, kind string, ls labelstore.LabelStore) crdManagerInterface
+}
+
+type realCrdManagerFactory struct{}
+
+func (realCrdManagerFactory) New(opts component.Options, cluster cluster.Cluster, logger log.Logger, args *operator.Arguments, kind string, ls labelstore.LabelStore) crdManagerInterface {
+	return newCrdManager(opts, cluster, logger, args, kind, ls)
+}
+
 // crdManager is all of the fields required to run a crd based component.
 // on update, this entire thing should be recreated and restarted
 type crdManager struct {
@@ -237,7 +254,7 @@ func (c *crdManager) DebugInfo() interface{} {
 	return info
 }
 
-func (c *crdManager) getScrapeConfig(ns, name string) []*config.ScrapeConfig {
+func (c *crdManager) GetScrapeConfig(ns, name string) []*config.ScrapeConfig {
 	prefix := fmt.Sprintf("%s/%s/%s", c.kind, ns, name)
 	matches := []*config.ScrapeConfig{}
 	for k, v := range c.scrapeConfigs {

internal/component/prometheus/operator/common/crdmanager_test.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"context"
 	"testing"
 
 	"golang.org/x/exp/maps"
@@ -167,3 +168,34 @@ func (m *mockScrapeManager) TargetsActive() map[string][]*scrape.Target {
 func (m *mockScrapeManager) ApplyConfig(cfg *config.Config) error {
 	return nil
 }
+
+type crdManagerFactoryHungRun struct{}
+
+func (crdManagerFactoryHungRun) New(opts component.Options, cluster cluster.Cluster, logger log.Logger, args *operator.Arguments, kind string, ls labelstore.LabelStore) crdManagerInterface {
+	return &crdManagerHungRun{}
+}
+
+type crdManagerHungRun struct{}
+
+func (c *crdManagerHungRun) Run(ctx context.Context) error {
+
+}
+
+func (c *crdManagerHungRun) ClusteringUpdated() {}
+
+func (c *crdManagerHungRun) DebugInfo() interface{} {
+	return nil
+}
+
+func (c *crdManagerHungRun) GetScrapeConfig(ns, name string) []*config.ScrapeConfig {
+	return nil
+}
+
+func TestRunExit(t *testing.T) {
+	// Create a Component
+	// Call component.Run
+	// Cancel the context.
+	// Make sure component.Run didn't exit for a few seconds
+	// Make crdManager.Run exit
+	// Make sure component.Run exits
+}